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We investigated clinically suspected measles cases that had discrepant real-time reverse transcription PCR (rRT-PCR) and measles-specific IgM test results to determine diagnoses. We performed rRT-PCR and measles-specific IgM testing on samples from 541 suspected measles cases. Of the 24 IgM-positive and rRT-PCR­–negative cases, 20 were among children who received a measles-containing vaccine within the previous 6 months; most had low IgG relative avidity indexes (RAIs). The other 4 cases were among adults who had an unknown previous measles history, unknown vaccination status, and high RAIs. We detected viral nucleic acid for viruses other than measles in 15 (62.5%) of the 24 cases with discrepant rRT-PCR and IgM test results. Measles vaccination, measles history, and contact history should be considered in suspected measles cases with discrepant rRT-PCR and IgM test results. If in doubt, measles IgG avidity and PCR testing for other febrile exanthematous viruses can help confirm or refute the diagnosis.

Mongolia experienced a nationwide measles outbreak during 1 March 2015–31 December 2016, with 49,077 cases reported to the WHO; many were among vaccinated young adults, suggesting a possible role of vaccine failure. Advanced laboratory methods, coupled with detailed epidemiological investigations, can help classify cases as vaccine failure, failure to vaccinate, or both. In this report, we conducted a study of cases to identify risk factors for breakthrough infection for a subset of laboratory-confirmed measles cases. Of the 193 cases analyzed, only 19 (9.8%) reported measles vaccination history, and 170 (88%) were uncertain. Measles-specific IgG avidity testing classified 120 (62%) cases as low IgG avidity, indicating no prior exposure to measles. Ten of these cases with low IgG avidity had a history of measles vaccination, indicating primary vaccine failure. Overall, sixty cases (31%) had high IgG avidity, indicating breakthrough infection after prior exposure to measles antigen through vaccination or natural infection, but the IgG avidity results were highly age-dependent. This study found that among young children aged 9 months–5 years, breakthrough infection was rare (4/82, 5%); however, among young adults aged 15–25 years, breakthrough infection due to secondary vaccine failure (SVF) occurred on a large scale during this outbreak, accounting for the majority of cases (42/69 cases, 61%). The study found that large-scale secondary vaccine failure occurred in Mongolia, which highlights the potential for sustained outbreaks in post-elimination settings due to "hidden" cohorts of young adults who may have experienced waning immunity. This phenomenon may have implications for the sustainability of measles elimination in countries that remain vulnerable to the importation of the virus from areas where it is still endemic. Until global measles elimination is achieved, enhanced surveillance and preparedness for future outbreaks in post- or peri-elimination countries may be required. [ABSTRACT FROM AUTHOR]

This study evaluated whether IgG avidity measured by chemiluminescent microparticle immunoassay (CMIA) compared with enzyme-linked immunosorbent assay (ELISA) was useful to detect primary T. gondii infection during pregnancy and to estimate the risk for congenital T. gondii infection. One hundred six women with positive tests for T. gondii IgG and T. gondii IgM, comprising 21 women (19.8%) with low (<30%), 6 (5.7%) with borderline (30%–35%), and 79 (74.5%) with high (>35%) IgG avidity measured by ELISA were selected. Their stored sera were used for T. gondii IgG avidity measurements by CMIA. In CMIA, 72 (67.9%) women had low (<50%), 12 (11.3%) had borderline (50%–59.9%), and 22 (20.8%) had high (≥60%) IgG avidity. The ratio of low T. gondii IgG avidity index in CMIA was more than three-fold than that in ELISA. Eighteen (85.7%) of 21 women with ELISA low avidity also had CMIA low avidity, and 26 (96.3%) of 27 women with ELISA low or borderline avidity corresponded to CMIA low or borderline avidity, whereas 21 (26.6%) of 79 women with ELISA high avidity were diagnosed with CMIA low avidity. All three cases with congenital T. gondii infection showed coincidentally low IgG avidity in both methods. A positive correlation in IgG avidity indices was found between of ELISA and CMIA. CMIA for T. gondii avidity measurements compared with ELISA was clinically useful to detect pregnant women at a high risk of developing congenital T. gondii infection. [ABSTRACT FROM AUTHOR]

Fasciola hepatica , a worldwide distributed helminth, has a robust immunoregulatory effect in the host, increasing the susceptibility to secondary infections. Foot and mouth disease (FMD) is a highly contagious acute vesicular viral disease effectively controlled by vaccination in endemic regions. Despite the evidence of immunoregulatory effects, the impact of fasciolosis on the immune response induced by FMD vaccination in cattle has never been assessed. Our objective was to evaluate whether the infection by F. hepatica in cattle influences the long-term immunity elicited by the currently used commercial FMD-inactivated vaccines. Aberdeen Angus steers negative for F. hepatica were vaccinated twice against FMD virus (FMDV) during the first 6 months of age using a commercial oil vaccine formulated with A24/Cruzeiro and O1/Campos strains. When maternal antibodies against F. hepatica were weaned (18––20 months of age) animals were divided into groups of 12 and infected or mock-infected with 500 metacercariae/animal. Individual serum samples were collected at 0-, 28-, 59-, 87- and 157-days post-infection (dpi). Indirect ELISAs were used to detect A24/Cruzeiro specific bovine IgG and IgG subtypes. The total IgG antibody levels and avidity against FMDV did not show significant differences between all the groups. The commercial vaccine induced higher IgG2 than IgG1 titers in vaccinated animals. Anti-FMDV IgG1 levels significantly decreased in the infected group at 28 dpi. In addition, the avidity of IgG1 FMDV-specific antibodies at day 28 in the infected group was reduced compared to the control. These results show that F. hepatica infection modified anamnestic responses against FMDV, reducing serum IgG1 titers and avidity. To our knowledge, this is the first report of immune-regulation of F. hepatica altering the immune response of FMD vaccines, one of the most globally used animal vaccines. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a protozoan parasite that is widely distributed in the human population and is responsible for corresponding global morbidity. Specifically, T. gondii causes toxoplasmosis, leading to miscarriage, stillbirth, and neural disorders. This parasite attacks different human organs and glands, such as the thyroid gland, and causes various corresponding health issues. Recently, studies have established a link between T. gondii and autoimmune thyroid diseases (AITD), which contributes to preterm delivery, miscarriage, low birth weight, and death. Therefore, the aim of this study was to detect the prevalence of toxoplasmosis and its association with AITD among pregnant women. A total of 180 blood samples were collected from pregnant women and examined using an enzyme-linked immunosorbent assay (ELISA). The patients were within the age range of 15–50 years old, and lived in Duhok City, Iraq; samples and clinical information was collected from August 2021 to February 2022. The corresponding blood samples were tested for anti-Toxoplasma IgG antibody, Toxoplasma IgG avidity, FT3, FT4, and TSH hormones, and TPO, Tg, and TSHR antibodies. Overall, our results showed that out of 180 pregnant women, 110 (61.1%) were seropositive for anti-Toxoplasma IgG antibody; specifically, 25 (22.7%) and 85 (77.3%) had recent and past infections, respectively. Approximately 54.4% (98) of the pregnant women had thyroid disorders; further, 22 (12.2%), 13 (7.2%), and 8 (4.4%) women had TPO, Tg, and TSHR antibodies, respectively. A total of 43 (23.8%) patients screened positive for AITD. Out of the 110 Toxoplasma IgG–positive women, 35 (31.8%) had AITD. The older women, rural residents, restaurant food consumers, and women with cat contact had relatively high infection rates. Toxoplasma seropositive women had more elevated autoantibodies than seronegative ones. In conclusion, this study demonstrated a high rate of toxoplasmosis and a corresponding association with thyroid hormones changes and AITD in pregnant women in Duhok, Iraq. Further, it is necessary to reduce overall infection rates through effective health and educational programs. Therefore, it is essential to measure Toxoplasma antibodies, screen for thyroid hormones and autoantibodies, and encourage gynecologist visits to reduce the risks to mothers and fetuses.

Mongolia experienced a nationwide measles outbreak during 1 March 2015–31 December 2016, with 49,077 cases reported to the WHO; many were among vaccinated young adults, suggesting a possible role of vaccine failure. Advanced laboratory methods, coupled with detailed epidemiological investigations, can help classify cases as vaccine failure, failure to vaccinate, or both. In this report, we conducted a study of cases to identify risk factors for breakthrough infection for a subset of laboratory-confirmed measles cases. Of the 193 cases analyzed, only 19 (9.8%) reported measles vaccination history, and 170 (88%) were uncertain. Measles-specific IgG avidity testing classified 120 (62%) cases as low IgG avidity, indicating no prior exposure to measles. Ten of these cases with low IgG avidity had a history of measles vaccination, indicating primary vaccine failure. Overall, sixty cases (31%) had high IgG avidity, indicating breakthrough infection after prior exposure to measles antigen through vaccination or natural infection, but the IgG avidity results were highly age-dependent. This study found that among young children aged 9 months–5 years, breakthrough infection was rare (4/82, 5%); however, among young adults aged 15–25 years, breakthrough infection due to secondary vaccine failure (SVF) occurred on a large scale during this outbreak, accounting for the majority of cases (42/69 cases, 61%). The study found that large-scale secondary vaccine failure occurred in Mongolia, which highlights the potential for sustained outbreaks in post-elimination settings due to “hidden” cohorts of young adults who may have experienced waning immunity. This phenomenon may have implications for the sustainability of measles elimination in countries that remain vulnerable to the importation of the virus from areas where it is still endemic. Until global measles elimination is achieved, enhanced surveillance and preparedness for future outbreaks in post- or peri-elimination countries may be required.

Toxoplasma gondii is a protozoan parasite that is widely distributed in the human population and is responsible for corresponding global morbidity. Specifically, T. gondii causes toxoplasmosis, leading to miscarriage, stillbirth, and neural disorders. This parasite attacks different human organs and glands, such as the thyroid gland, and causes various corresponding health issues. Recently, studies have established a link between T. gondii and autoimmune thyroid diseases (AITD), which contributes to preterm delivery, miscarriage, low birth weight, and death. Therefore, the aim of this study was to detect the prevalence of toxoplasmosis and its association with AITD among pregnant women. A total of 180 blood samples were collected from pregnant women and examined using an enzyme-linked immunosorbent assay (ELISA). The patients were within the age range of 15–50 years old, and lived in Duhok City, Iraq; samples and clinical information was collected from August 2021 to February 2022. The corresponding blood samples were tested for anti-Toxoplasma IgG antibody, Toxoplasma IgG avidity, FT3, FT4, and TSH hormones, and TPO, Tg, and TSHR antibodies. Overall, our results showed that out of 180 pregnant women, 110 (61.1%) were seropositive for anti-Toxoplasma IgG antibody; specifically, 25 (22.7%) and 85 (77.3%) had recent and past infections, respectively. Approximately 54.4% (98) of the pregnant women had thyroid disorders; further, 22 (12.2%), 13 (7.2%), and 8 (4.4%) women had TPO, Tg, and TSHR antibodies, respectively. A total of 43 (23.8%) patients screened positive for AITD. Out of the 110 Toxoplasma IgG–positive women, 35 (31.8%) had AITD. The older women, rural residents, restaurant food consumers, and women with cat contact had relatively high infection rates. Toxoplasma seropositive women had more elevated autoantibodies than seronegative ones. In conclusion, this study demonstrated a high rate of toxoplasmosis and a corresponding association with thyroid hormones changes and AITD in pregnant women in Duhok, Iraq. Further, it is necessary to reduce overall infection rates through effective health and educational programs. Therefore, it is essential to measure Toxoplasma antibodies, screen for thyroid hormones and autoantibodies, and encourage gynecologist visits to reduce the risks to mothers and fetuses. [ABSTRACT FROM AUTHOR]

Gaining more appreciation on the protective/damaging aspects of anti-SARS-CoV-2 immunity associated with disease severity is of great importance. This study aimed to evaluate the avidity of serum IgG antibodies against SARS-CoV-2 spike (S) and nucleocapsid (N) in hospitalized symptomatic COVID-19 patients and asymptomatic RT-PCR-confirmed SARS-CoV-2 carriers as well as to compare antibody avidities with respect to vaccination status, vaccination dose and reinfection status. Serum levels of anti-S and anti-N IgG were determined using specific ELISA kits. Antibody avidity was determined by urea dissociation assay and expressed as avidity index (AI) value. Despite higher IgG levels in the symptomatic group, AI values of both anti-S and anti-N IgG were significantly lower in this group compared to asymptomatic individuals. In both groups, anti-S AI values were elevated in one-dose and two-dose vaccinees versus unvaccinated subjects, although significant differences were only detected in the symptomatic group. However, anti-N avidity showed no significant difference between the vaccinated and unvaccinated subgroups. Almost all vaccinated patients of different subgroups (based on vaccine type) had higher anti-S IgG avidity, while the statistical significance was detected only between those receiving Sinopharm compared to the unvaccinated subgroup. Also, statistically significant differences in antibody AIs were only found between primarily infected individuals of the two groups. Our findings indicate a key role for anti-SARS-CoV-2 IgG avidity in protection from symptomatic COVID-19 and calls for the incorporation of antibody avidity measurement into the current diagnostic tests to predict effective immunity toward SARS-CoV-2 infection or even for prognostic purposes. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed at determining the prevalence of CMV infection among pregnant women at the end of pregnancy and CMV transmission to their newborns. Methods: This is cross sectional study, 213 pregnant women at delivery and their newborn babies from the Obstetrics and Gynecology Hospital in Duhok/Iraq were enrolled. A questionnaire was prepared to be answered by participants, including age, place of residence, educational level, and obstetric history as number of births, any bad obstetric history such as abortion, still birth, intrauterine growth retardation, congenital anomalies after birth. 3-5 ml of blood was drawn from each woman and examined by ELISA kit to check for the presence of Anti CMV IgM, IgG, then IgG avidity test for those with positive (IgG and IgM). Samples of cord blood were collected from newborns after birth and checked for the presence of CMV IgM by ELISA and CMV--DNA by conventional PCR using specific primers to diagnose congenital infection and determine the rate of viral transmission from infected women. Results: Serological examinations showed that 212 (99.5%) participants were CMV-IgG positive, 15 (7%) were positive for anti-CMV IgM and IgG antibodies, IgG avidity test for 15 women were of high avidity (>89%) which indicated non primary infections. Cord blood of newborns of those 15 women with positive IgG and IgM tested negative for Anti CMV IgM by ELISA and no CMV-DNA was detected by PCR, which revealed no transmission from those pregnant to their newborns. Conclusion: This study demonstrated high prevalence of CMV among examined pregnant women in Duhok city which makes them prone to non-primary infection. IgG avidity test is of high efficacy to interpret the detection of IgG and IgM together in pregnant women. Cord blood examination for the existence of CMV-IgM and CMV-DNA after delivery could exclude congenital infection. [ABSTRACT FROM AUTHOR]

Background and Objective: The most important concern associated with diagnosing congenital toxoplasmosis is to determine when the mother has been infected. The importance of using serological diagnostic tests such as IgG-avidity assay which can distinguish between recent and past infections has been proven. The present study aimed to diagnose acute toxoplasmosis in the first trimester of pregnancy using IgG-avidity testing. Materials and Methods: The present descriptive cross-sectional study was conducted in Hamadan, Iran in 2019. A total of 340 blood samples were collected from pregnant women in the first trimester of pregnancy and stored at -70 °C until experimenting. The IgG antibody titer was then determined. Also, IgM and IgG-avidity titers were measured for those samples with a positive IgG titer. Results: Out of 340 pregnant women, 106 (31.2%) had a positive and 2 (0.6%) had a suspected IgM test. Of the 106 pregnant mothers with positive IgG, 6 (5.66%) had low IgG-avidity indicating recent infection of toxoplasmosis in the past 3 to 4 months. IgG-avidity titer was moderate in 10 patients (9.43%) and high in 90 patients (84.9%). Conclusion: Using the IgG-avidity test and its improved methods along with other serological and molecular methods can be effective in determining and differentiating acute toxoplasmosis in pregnant women, especially in the first trimester of pregnancy, and preventing its irreversible complications in the fetus.

Abstract Objective The purpose of the present study is to standardize and evaluate the use of the immunoglobulin G (IgG) antibody avidity test on blood samples from newborns collected on filter paper to perform the heel test aiming at its implementation in ongoing programs. Methods Blood samples from newborns were collected on filter paper simultaneously with the heel prick test. All samples were subjected to immunoglobulin M IgM and IgG enzyme-linked immunosorbent assays (ELISA). Peripheral blood was collected again in the traditional way and on filter paper from newborns with high IgG levels (33). Three types of techniques were performed, the standard for measuring IgG in serum, adapted for filter paper and the technique of IgG avidity in serum and on filter paper. The results of the avidity test were classified according to the Rahbari protocol. Results Among the 177 samples, 17 were collected in duplicate from the same child, 1 of peripheral blood and 1 on filter paper. In this analysis, 1 (5.88%) of the 17 samples collected in duplicate also exhibited low IgG avidity, suggesting congenital infection. In addition, the results obtained from serum and filter paper were in agreement, that is, 16 (94.12%) samples presented high avidity, with 100% agreement between the results obtained from serum and from filter paper. Conclusion The results of the present study indicate that the avidity test may be another valuable method for the diagnosis of congenital toxoplasmosis in newborns.

Background/Aim Congenital human cytomegalovirus infection (cCMV) is the commonest congenital infection, and it can result in hearing loss and neurodevelopmental delay. Even if primary infections are more frequent and cause more severe congenital cCMV manifestations compared to NPIs, and despite partial protection from maternal immunity, the highest birth prevalence of cCMV is observed in seropositive women with non-primary CMV infection (NPI). Given that NPI contribute significantly to the overall burden of cCMV, their accurate diagnosis of NPI remains clinically important. Considering that the serological testing for CMV infection is not always reliable, we sought to determine whether detection of CMV DNA in pregnant women with a high IgG avidity index (AI) can help diagnose NPI. Materials and methods Human CMV serology screening (IgG, IgM, and IgG AI) was performed for confirmation of CMV infection in serum samples from mainly pregnant women with indications of CMV infection due to IgG+ and IgM+-positive samples in other laboratories. Pregnant women (or those with termination of pregnancy during the last period) with adequate IgG levels to perform IgG AI were included. Demographic data and mean gestation week at the time of screening were recorded. Serological testing was performed using CE-IVD commercial kits. CMV DNAemia detection by real time PCR (RT-PCR) was applied to confirm suspected CMV infection. Results Nine-hundred and thirty-four pregnant women CMV IgG positive with adequate IgG titers for AI testing were included in the study. The percentage of women with a high AI was 71.8% (671/934); among them, nearly 2.4% (16/671) had presence of CMV DNA. Also, 12.4% of women (116/934) had intermediate IgG AI and 15.7% of women (147/934) had low IgG AI. The presence of CMV DNA was observed in 13.8% (16/116) and 39.5% (58/147) of the groups with intermediate and low IgG AI, respectively. A high CMV IgG AI was associated with a negative CMV PCR status (p-value <.00001). Conclusions CMV DNA was present in 2.4% of seropositive women with high IgG AI, indicating active NPI and thus, harboring the risk of cCMV sequelae to the fetus. Moreover, the incidence of NPI may have been underestimated due to single timepoint testing. In order to detect CMV NPI in a seropositive woman, regular and frequent serology testing as well as detection of CMV DNAemia are required which render the whole diagnostic process impractical and not cost-effective. [ABSTRACT FROM AUTHOR]

Background: The diagnosis of West Nile virus (WNV) is challenging due to short-term and low-level viremia, flavivirus cross-reactivity, and long immunoglobulin M (IgM) persistence., Aim: To evaluate different methods for WNV detection [reverse transcription-polymerase chain reaction (RT-PCR), IgM/IgG antibodies, IgG avidity] in serum, cerebrospinal fluid (CSF), and urine samples of patients with confirmed WNV infection., Methods: The study included patients with confirmed WNV neuroinvasive infection ( n = 62), asymptomatic WNV seropositive individuals ( n = 22), and individuals with false-positive WNV IgM antibodies ( n = 30). WNV RNA was detected using RT-PCR. A commercial ELISA was used to detect WNV IgM/IgG antibodies with confirmation of cross-reactive samples using a virus neutralization test (VNT). IgG-positive samples were tested for IgG avidity., Results: The WNV-RNA detection rates were significantly higher in the urine (54.5%)/serum (46.4%) than in CSF (32.2%). According to the sampling time, the WNV-RNA detection rates in urine collected within 7 days/8-14/≥ 15 days were 29.4/66.6/62.5% ( P = 0.042). However, these differences were not observed in the CSF. The median RT-PCR cycle threshold values were significantly lower in urine (32.5, IQR = 28-34) than in CSF (34.5, IQR = 33-36). The frequency of positive WNV IgM and IgG significantly differed according to the sampling time in serum but not in CSF. Positive IgM/IgG antibodies were detected in 84.3/9.3% of serum samples collected within 7 days, 100/71.1% of samples collected 8-14, and 100% samples collected after ≥ 15 days. Recent WNV infection was confirmed by low/borderline avidity index (AI) in 13.6% of asymptomatic individuals. A correlation between ELISA and AI was strong negative for IgM and strong positive for IgG. No significant correlation between ELISA IgG and VNT was found., Conclusion: The frequency of WNV RNA and antibody detection depends on the sampling time and type of clinical samples. IgG avidity could differentiate recent WNV infections from long-persisting IgM antibodies., Competing Interests: Conflict-of-interest statement: All authors reported no conflicts of interest., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

Toxoplasma gondii, an obligate intracellular protozoan parasite, is the causative agent of one of the most prevalent zoonoses worldwide. T. gondii infection is extremely important from a medical point of view, especially for pregnant women, newborns with congenital infections, and immunocompromised individuals. Thus, an accurate and proper diagnosis of this infection is essential. Among the available diagnostic tests, serology is commonly used. However, traditional serological techniques have certain limitations in evaluating the duration of T. gondii infection, which is problematic, especially for pregnant women. Avidity of T. gondii-specific IgG antibodies seems to be a significant tool for discrimination between recent and distant infections. This article describes the problem of diagnosis of T. gondii infection, with regard to IgG avidity tests. The IgG avidity test is a useful serological indicator of toxoplasmosis, which in many cases can confirm or exclude the active form of the disease. IgG antibodies produced in the recent primary T. gondii infection are of low avidity while IgG antibodies with high avidity are detected in the chronic phase of infection. Furthermore, this paper presents important topics of current research that concern the usage of parasite recombinant antigens that may improve the performance of IgG avidity tests. [ABSTRACT FROM AUTHOR]

Background: Diagnosis of prolonged febrile illness of unknown origin (FUO) is challenging even with the advances in the diagnostic techniques. As common as the infection with cytomegalovirus (CMV) is, most health care providers would not suspect CMV infection as a cause of FUO unless mononucleosis syndrome is evident. The aim of this study is to investigate the rate of CMV infection among patients with FUO and shed light on IgG avidity as a diagnostic tool. Patients and methods: Two hundred and twenty three (223) immune competent patients with FUO were included in our study. They were subjected to all routine laboratory investigations, fever agglutinins, tuberculin and abdominal ultrasound along with IgG and IgM for CMV and IgG avidity test. Results: This study shows that the 92.8% of the overall studied population were positive for CMV IgG. However, only 74(33.2%) of the studied population was found positive for IgM. Only one patient had positive IgM with negative IgG. IgG avidity was high in almost all of them. Only 3 patients showed low IgG avidity denoting that they have primary infection. Conclusion: CMV infection was found to be the cause of 33.2% of prolonged febrile illness experienced by immuncompetent adults. Only 1.8% of patients had primary CMV infection and the majority of them had detectable IgG level and were diagnosed with primary infection depending mainly on IgG avidity test. [ABSTRACT FROM AUTHOR]

In regions where the endemic measles virus has been eliminated, early detection of contagious patients is important for preventing the spread of measles and sustaining elimination. To investigate whether serological assays can be used for the estimation of highly infectious patients with measles, we performed a seroepidemiologic study of a measles outbreak in Yamagata Prefecture, Japan, in 2017. We tested plaque reduction neutralization (PRN), IgG avidity, and gelatin particle agglutination (PA) assays in 31 patients with measles, subdivided into two super-spreaders, three spreaders, and 26 non-spreaders. Simultaneously, these results were compared with the cycle threshold (Ct) of a semi-quantitative real-time reverse transcription PCR for the measles virus from throat swab specimens. In the PRN assay, one super-spreader and two spreaders lacked protective antibodies. The IgG avidity assay showed that two super-spreaders and one spreader had low avidity. The PA assay indicated that two super-spreaders and two spreaders lacked protective antibodies. Comparison of the results of the three serological assays and Ct revealed that patients whose antibody titers were judged as low in the IgG avidity and PA assays showed low Ct (i.e., high viral load), whereas non-spreaders tended to show low viral load. Our preliminary seroepidemiologic analysis of a population of 31 patients with measles suggests that PA and IgG avidity assays may be used for the identification of super-spreader/spreader candidates. However, further investigations are necessary to validate the robustness of these serological assays in detecting contagious measles cases. [ABSTRACT FROM AUTHOR]

Abstract Objectives The aim of the current study was to assess prevalence of Toxoplasma infection and its associated risk factors in women of childbearing-age in central Iran. Results Of 400 serum samples assessed for anti-T. gondii antibodies, 81 (20.25%) samples were positive for anti-T. gondii antibodies, including 74 positive samples (91.3%) for anti-T. gondii IgG and seven positive samples (8.7%) for IgG and IgM. Of seven IgG and IgM positive samples, five and two samples were high and low in IgG avidity, respectively. Based on PCR analysis, Toxoplasma infection was detected in one sample with anti-T. gondii IgM and low IgG avidity. The Chi-square test showed significant correlations of T. gondii seropositivity with history of undercooked meat consumption and contacts with cats (p

Immunoglobulin G (IgG) and immunoglobulin M (IgM) testing are commonly used to determine infection status. Typically, the detection of IgM indicates an acute or recent infection, while the presence of IgG alone suggests a chronic or past infection. However, relying solely on IgG and IgM antibody positivity may not be sufficient to differentiate acute from chronic infections. This limitation arises from several factors. The prolonged presence of IgM can complicate diagnostic interpretations, and false positive IgM results often arise from antibody cross-reactivity with various antigens. Additionally, IgM may remain undetectable in prematurely collected samples or in individuals who are immunocompromised, further complicating accurate diagnosis. As a result, additional diagnostic tools are required to confirm infection status. Avidity is a measure of the strength of the binding between an antigen and antibody. Avidity-based assays have been developed for various infectious agents, including toxoplasma, cytomegalovirus (CMV), SARS-CoV-2, and avian influenza, and are promising tools in clinical diagnostics. By measuring the strength of antibody binding, they offer critical insights into the maturity of the immune response. These assays are instrumental in distinguishing between acute and chronic or past infections, monitoring disease progression, and guiding treatment decisions. The development of automated platforms has optimized the testing process by enhancing efficiency and minimizing the risk of manual errors. Additionally, the recent advent of real-time biosensor immunoassays, including the label-free immunoassays (LFIA), has further amplified the capabilities of these assays. These advances have expanded the clinical applications of avidity-based assays, making them useful tools for the diagnosis and management of various infectious diseases. This review is structured around several key aspects of IgG avidity in clinical diagnosis, including: (i) a detailed exposition of the IgG affinity maturation process; (ii) a thorough discussion of the IgG avidity assays, including the recently emerged biosensor-based approaches; and (iii) an examination of the applications of IgG avidity in clinical diagnosis. This review is intended to contribute toward the development of enhanced diagnostic tools through critical assessment of the present landscape of avidity-based testing, which allows us to identify the existing knowledge gaps and highlight areas for future investigation.

The avidity index (AI) of IgG to the RBD of SARS-CoV-2 was determined for 71 patients with a mild (outpatient) course of COVID-19, including 39 primarily and 36 secondarily reinfected, and 92 patients with a severe (hospital) course of COVID-19, including 82 primarily and 10 secondarily infected. The AI was shown to correlate with the severity of repeated disease. In the group of outpatients with a mild course, the reinfected patients had significantly higher median AIs than those with primary infections (82.3% vs. 37.1%, p < 0.0001). At the same time, in patients with a severe course of COVID-19, reinfected patients still had low-avidity antibodies (median AI of 28.4% vs. 25% in the primarily infected, difference not significant, p > 0.05). This suggests that the presence of low-avidity IgG to RBD during reinfection is a negative prognostic factor, in which a patient's risk of developing COVID-19 in a severe form is significantly increased. Thus, patients with IgG of low avidity (AI ≤ 40%) had an 89 ± 20.5% chance of a severe course of recurrent COVID-19, whereas the detection of high-avidity antibodies (AI ≥ 50%) gave a probability of 94 ± 7.9% for a mild course of recurrent disease (p < 0.05). [ABSTRACT FROM AUTHOR]

Objective: Toxoplasmosis acquired in early pregnancy is a potentially severe complication for the fetus. Evaluating the risk of transplacental infection in pregnant women accessing the Tuscany Reference Center for Infectious Diseases in Pregnancy during the last 20 years with suspected or confirmed toxoplasmosis acquired in early pregnancy was the aim of the study.Study Design: We retrospectively enrolled all pregnant women undergoing amniocentesis for toxoplasmosis acquired in the first 16 gestational weeks in the period 1999-2019, comparing patients with certain acute infection (seroconversion occurred in pregnancy, CAIP) with those with suspected acute infection (IgG positive with low/intermediate IgG avidity index, SAIP).Results: 237 patients were enrolled, 187 (78.9%) with SAIP and 50 (21.1%) with CAIP. Specific IgM was detected in 47.5% and 76.7% (p-value 0.001), and the mean IgG avidity index was 22.7% and 7.1% (p-value < 0.001) in the SAIP and in the CAIP group, respectively. The mean delay from diagnosis to antibiotic initiation was 14.6 in SAIP and 11 days in CAIP group. Toxoplasma DNA was detected in the amniotic fluid in one case in a patient with CAIP. Excluding 24 newborns with not available data, prevalence of congenital infection was 0.47% [1/213 (95% CI 0.08%-2.61%)], 0% [0/178 (95% CI 0%-2.11%)] in SAIP and 2.8% [1/35 (95% CI 0.51%-14.53%)] in CAIP group.Conclusions: Toxoplasmosis acquired in early pregnancy has a low risk of fetal infection. Actively discussing case-by-case amniocentesis indication with patients, especially when a recent toxoplasmosis is not properly confirmed, is desirable. [ABSTRACT FROM AUTHOR]

Juvenile Idiopathic Arthritis (JIA) patients living in areas with high prevalence of tick-borne-encephalitis-virus-(TBEV)-infection are recommended for administration of inactivated TBE-vaccination. However, there are serious concerns regarding protective vaccine-induced immune responses against TBEV in immunocompromised patients. The present study aimed to analyze the humoral and cellular immune response to TBE-vaccination in previously TBE-vaccinated JIA patients compared to healthy controls (HC) including investigation of IgG-anti-TBEV avidity, neutralization capacity, cellular reactivity by IFNgamma-ELISPOT and cytokine secretion assays. Similar IgG-anti-TBEV antibody concentrations, neutralization titers and cellular reactivity were found between JIA and HC. The number and the early timing of booster vaccinations after primary vaccination had the most prominent effect on neutralizing antibodies in JIA and on IgG-anti-TBEV concentrations in both JIA and HC. Administration of booster vaccinations made it more likely for JIA patients to have IgG-anti-TBEV concentrations ≥165 VIEU/ml and avidities >60%. TNF-alpha inhibitors had a positive and MTX administration a negative effect on humoral immune responses. In conclusion, irrespective of having JIA or not, vaccinated children showed similar humoral and cellular immunity against TBEV several years after primary TBE-vaccination. However, in JIA, booster vaccinations mounted a significantly higher humoral immune response than in JIA without boosters. Our results highlight the need for timely administration of boosters particularly in JIA. Although immunosuppressive treatment at vaccinations in diagnosed JIA had a negative effect mainly on TBEV-specific cellular immunity, most JIA patients mounted a favorable humoral immune response which was maintained over time. Thus, successful TBE-vaccination seems highly feasible in JIA patients with immunosuppressive regimens. [ABSTRACT FROM AUTHOR]

This study intended to evaluate the seroprevalence of anti-Toxoplasma IgG and IgM antibodies in the sera of 630 women at childbearing age, and to link the outcomes with some risk factors. The enrolled women visited Zakho Maternity Hospital from July 2018 to July 2019. Their ages ranged from 15 to 45 years. All samples were examined using ELISA to detect immunoglobulin G and M, in addition to performing IgG Avidity test for seropositive pregnant women. The differences between seropositivity and age was significant (p<0.05), the highest rate (20.43%) for anti-Toxoplasma IgG antibodies in the age group 33-38 years. Women who had more contact with cats showed higher IgG and IgM seropositivity rates (16.45% and 1.26%, respectively). Married women had higher IgG Abs seropositivity than single ones (12.52% vs 6.31%, respectively), moreover, only married women were seropositive for IgM Abs. Pregnant women presented higher IgG Abs seropositivity than nonpregnant (15.21% versus 10.49%), with almost equal seropositivity for IgM Abs (0.65% and 0.86%, respectively). Anti-Toxoplasma IgG Abs seropositivity was higher in women underwent miscarriages than those with normal pregnancies (18.44 vs. 8.81%), however IgM Abs was only found among women who had miscarriages (0.97%). Women with triple miscarriages presented the highest IgG Abs seropositivity (37.03%). Chronic infection was found in 68.75% of pregnant women, whereas acute infection was found in 31.25 %. Following up the pregnancy resulted in 15 healthy births, 9 miscarriages, and 10 women did not show up. The finding of this study demonstrates the relationship between toxoplasmosis and risk factors in women at childbearing age, with the aims of decreasing infection rates through the introducing of health education programs and the application of hygienic measures in the community by health authority. [ABSTRACT FROM AUTHOR]

[Display omitted] • SARS CoV-2 and Toxoplasma gondii are widespread infectious agents that can be expected to co-exist in a large number of patients. • Cytokines are important determinants of the severity of COVID-19 manifestations. • Toxoplasmosis induces immune modulation which reflects on concomitant infections when present. • The study of the effect of co-infection between these two pathogens on cytokine response and clinical outcome must be solidated by mass studies. The symptomatology of COVID-19 is dependent on the immune status and the cytokine response of the host. The cytokine level of the host is influenced by the presence of chronic persistent or latent infections with co-pathogens. Parasitic diseases are known to induce host immune-modulation which may impact the response to co-infection. Toxoplasmosis is a widespread protozoal infection that remains quiescent in its latent form to be re-activated during states of immune depression. Clinical data on the relation between toxoplasmosis and COVID-19 cytokine profile and symptomatology are still insufficient. Seventy-nine subjects were included in this study. Patients were diagnosed with COVID-19 by PCR. Serological testing for toxoplasmosis was performed by the detection of anti- Toxoplasma IgG antibodies, in addition to IgG avidity testing. IFN-γ and TNF-α levels were determined by RT-PCR. Among patients diagnosed with COVID-19, 67.1% were seronegative for anti- Toxoplasma IgG, while 32.9% were seropositive. High avidity was found in 10 cases (40% of seropositive cases), 4 of whom required ICU administration, while low avidity was found in 15 cases (60%), 7 of which were administered to the ICU. TNF-α and INF-γ levels were significantly higher in COVID-19 patients than in healthy control subjects. No significant association was found between the seroprevalence of toxoplasmosis and the presence of COVID-19 and its severity. Cytokines were significantly higher in both seropositive and seronegative COVID-19 patients than in their control counterparts. The high prevalence of toxoplasmosis merits further exploration of its relation to COVID-19 by mass studies. [ABSTRACT FROM AUTHOR]

Background Toxoplasma gondii is one of the major causes of abortion in pregnant women. Most cases of abortion occur in the acute phase of infection and early pregnancy. The purpose of this study was to investigate the association between spontaneous abortion and seropositive status of toxoplasmosis in women with first-time spontaneous abor- tion. Materials and Methods This research is a case-control study on 240 serum samples from women experiencing spon- taneous abortion for the first time as the case group, and 240 serum samples from women who had a normal delivery with no history of abortion as the control group. The level of anti-Toxoplasma gondii IgM and IgG antibodies were assessed in serum samples using ELISA. To separate the acute and chronic infections, all IgM-positive samples in both groups and IgG-positive samples of the case group were examined using IgG avidity. Results The Toxoplasma IgM antibody was detected in 3.3% (8/240) of the case group and 0.4% (1/240) of the con- trol group, which was a statistically significant difference between the two groups [P=0.019, odds ratio (OR)=10.266]. Of all samples 47.5% and 46.3% of the case and control groups were positive for Toxoplasma IgG antibody, respec- tively. Seven out of 8 (87.5%) IgM-positive serum samples from the case group had low IgG avidity, indicating acute infections, whereas all IgG-positive sera and 1 IgM-positive serum, which was related to the control group, showed a high IgG avidity, indicating chronic infections. Conclusion Maternal acute toxoplasmosis during pregnancy is raised as one of the factors that increase the chance of spontaneous abortion. The necessary health training, especially on the parasite transmission ways to women before marriage, as well as the serological test in women before and during pregnancy is recommended. Polymerase chain reaction (PCR) and IgG avidity assays should be performed in the medical diagnostic laboratories for accurate distin- guishing of the initial infection of toxoplasmosis in the pregnant women.

Background and aims: Toxoplasmosis is a very common disease in the world and has two types, including chronic and acute toxoplasmosis. In the chronic toxoplasmosis, the abnormality of tissue function is negligible, but in acute toxoplasmosis, the function of the reticuloendothelial system is interrupted and the assessment of Toxoplasma antibody with tissue enzymes is very essential in this stage. In addition, in some conditions, serum ferritin increases in the acute phase of the infectious disease. In congenital toxoplasmosis, the evaluation of biochemical factors and IgG avidity test is important for detecting the acute congenital toxoplasmosis in pregnant women. Based on the above-mentioned explanations, the present study aimed to evaluate the biochemical factors in patients with acute toxoplasmosis (congenital toxoplasmosis) among the Iranian population using electrochemiluminescence and IgG ELISA avidity. Methods: The study was based on a comparative abundance study and was conducted from March to June 2017. Material included 980 serum and amniotic fluid samples collected from human blood with a high level of IgG antibody against Toxoplasma gondii in Rajaie Center, Tehran, Iran. The standard and the main tests included the ELISA assay and the measurement of the liver transaminases (i.e., SGOT and SGPT), along with/namely bilirubin and ferritin used to detect IgG antibodies and to evaluate the acute toxoplasmosis, respectively. Finally, the results were analyzed by SPSS software. Results: The results showed that the level of liver transaminases, namely, serum bilirubin and ferritin increase in some patients with a high level of IgG avidity antibody against Toxoplasma gondii. For example, the mean serum levels of SGOT was 108 IU/L in 120 patients with acute toxoplasmosis and the mean serum bilirubin was about 5 mg/dL in 80 patients. Conclusion: Overall, in acute congenital toxoplasmosis, the evaluation of IgG AVIDITY is regarded as the first step and then the measurement of biochemical factors such as serum transaminases, serum bilirubin, and serum ferritin is important.

Toxoplasma gondii, an obligate intracellular protozoan parasite, is the causative agent of one of the most prevalent zoonoses worldwide. T. gondii infection is extremely important from a medical point of view, especially for pregnant women, newborns with congenital infections, and immunocompromised individuals. Thus, an accurate and proper diagnosis of this infection is essential. Among the available diagnostic tests, serology is commonly used. However, traditional serological techniques have certain limitations in evaluating the duration of T. gondii infection, which is problematic, especially for pregnant women. Avidity of T. gondii-specific IgG antibodies seems to be a significant tool for discrimination between recent and distant infections. This article describes the problem of diagnosis of T. gondii infection, with regard to IgG avidity tests. The IgG avidity test is a useful serological indicator of toxoplasmosis, which in many cases can confirm or exclude the active form of the disease. IgG antibodies produced in the recent primary T. gondii infection are of low avidity while IgG antibodies with high avidity are detected in the chronic phase of infection. Furthermore, this paper presents important topics of current research that concern the usage of parasite recombinant antigens that may improve the performance of IgG avidity tests.

Introduction: Cytomegalovirus (CMV) is the most common congenital viral infection and is regarded as the leading nongenetic cause of sensorineural hearing loss. Currently, international consensuses discourage prenatal screening of pregnant women. However, in few countries mainly in Southern Europe, screening of pregnant women for CMV infection is common practice. Management of women found with IgG+/IgM + and IgG avidity titers in the grey zone during first trimester causes significant stress to both families and health care workers.Patients and Methods: Pregnant women referred to our outpatient clinic with the diagnosis of acute CMV infection (IgM+/IgG+) during early pregnancy (gestational age ≤ 14 weeks) and IgG avidity in the grey zone were prospectively followed. The administration of CMV-HIG was offered and follow-up included fetal U/S, amniocentesis for CMV-DNA detection and MRI when appropriate. All neonates were examined by urine PCR and prospectively followed according to existing recommendations.Results: Ninety women (mean age 30.8 years) were retrospectively analyzed. Most (79.6%) received CMV-HIG. Four women terminated pregnancy (2 unrelated to CMV reasons and 2 because of CMV-positive amniotic fluid). Eighty-seven babies were born asymptomatic. Two newborns were diagnosed with congenital CMV infection. The overall transmission rate was 4.4%; 4.3 versus 5.6% for those receiving or not CMV-HIG. No adverse outcomes were detected during follow-up (median 24 months). Maternal age, parity, detection of maternal CMV-viremia upon diagnosis, delay between diagnosis and consultation, gestational week of first consultation, administration of CMV-HIG and number of doses were not associated with the risk of vertical CMV transmission.Discussions: Vertical transmission of CMV infection in pregnancies with acute CMV-infection and IgG avidity titers in the grey zone during first trimester was 4.4%, higher than that in infants born post nonprimary infection (NPI) during pregnancy. More powered studies are needed to prove a significant reduction in transmission using CMV-HIG. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the current study was to assess prevalence of Toxoplasma infection and its associated risk factors in women of childbearing-age in central Iran. Results: Of 400 serum samples assessed for anti-T. gondii antibodies, 81 (20.25%) samples were positive for anti-T. gondii antibodies, including 74 positive samples (91.3%) for anti-T. gondii IgG and seven positive samples (8.7%) for IgG and IgM. Of seven IgG and IgM positive samples, five and two samples were high and low in IgG avidity, respectively. Based on PCR analysis, Toxoplasma infection was detected in one sample with anti-T. gondii IgM and low IgG avidity. The Chi-square test showed significant correlations of T. gondii seropositivity with history of undercooked meat consumption and contacts with cats (p < 0.05). In the present study, 79.75% of the participants were negative for IgG against T. gondii infection. Furthermore, recently acquired Toxoplasma infection was found using IgG avidity and PCR assays among women of childbearing-age in the study area, which would increase the risk of their fetus becoming infected. Educational program and antenatal screening of childbearing-age women for T. gondii infection may be important primary prevention strategies and help reduce the risk of congenital toxoplasmosis in this population. [ABSTRACT FROM AUTHOR]

We investigated clinically suspected measles cases that had discrepant real-time reverse transcription PCR (rRT-PCR) and measles-specific IgM test results to determine diagnoses. We performed rRT-PCR and measles-specific IgM testing on samples from 541 suspected measles cases. Of the 24 IgM-positive and rRT-PCR--negative cases, 20 were among children who received a measles-containing vaccine within the previous 6 months; most had low IgG relative avidity indexes (RAIs). The other 4 cases were among adults who had an unknown previous measles history, unknown vaccination status, and high RAIs. We detected viral nucleic acid for viruses other than measles in 15 (62.5%) of the 24 cases with discrepant rRT-PCR and IgM test results. Measles vaccination, measles history, and contact history should be considered in suspected measles cases with discrepant rRT-PCR and IgM test results. If in doubt, measles IgG avidity and PCR testing for other febrile exanthematous viruses can help confirm or refute the diagnosis.

Background: When a pregnant woman contracts Toxoplasma gondii (T. gondii) infection during pregnancy, it may be vertically transmitted to the foetus. Information on the incidence of congenital toxoplasmosis (CT) in developing countries is scarce. Most studies focus on the seroprevalence of T. gondii infection among pregnant women. This study aimed to determine the seroprevalence of T. gondii infection among pregnant women attending public antenatal care in Windhoek, Namibia, in 2016. Methods: In this descriptive study, 344 urban pregnant women attending public antenatal care were voluntarily enrolled in the study. Seroprevalence of anti-T. gondii Immunoglobulin G (IgG) was determined by automated immunoassay. Samples with a positive T. gondii IgG result were tested for T. gondii Immunoglobulin M (IgM) and specific IgG avidity by using an enzyme-linked immunosorbent assay (ELISA) test. A questionnaire captured demographic data and exposure to risk factors. Data were analysed using Statistical Package for the Social Sciences (SPSS) and R. Results: Anti-T. gondii IgG was found in nine (2.61%) pregnant women. There was no association of anti-T. gondii IgG with demographic characteristics or exposure to risk factors.Anti-T. gondii IgM was positive in one (0.3%) woman, while three (0.9%) women had borderline anti-T. gondii IgM results. Specific IgG avidity was low, equivocal and high in 0%, 33% and 67% of seropositive pregnant women, respectively. Conclusion: Seroprevalence of anti-T. gondii IgG is much lower in Namibia than is reported in other developing countries. Investigation into specific IgM seropositivity and IgG avidity showed that pregnant women in the central region of Namibia are at low risk of vertical transmission and development of CT.

ABSTRACT Human parvovirus B19 (here B19), human cytomegalovirus (HCMV), and Toxoplasma gondii infections during pregnancy can lead to severe complications. While traditional diagnosis of infections is mostly confined to one pathogen at a time, a multiplex array is a feasible alternative to improve diagnostic management and cost-efficiency. In the present study, for these three pathogens, we developed microsphere-based suspension immunoassays (SIAs) in multiplex and monoplex formats for the detection of antimicrobial IgM antibodies as well as corresponding chaotrope-based IgG avidity SIAs. We determined the diagnostic performances of the SIAs versus in-house and commercial reference assays using a panel of 318 serum samples from well-characterized clinical cohorts. All the newly developed assays exhibited excellent performance compared to the corresponding high-quality reference methods. The positive and negative percent agreements of the IgM SIAs in comparison with reference methods were 95 to 100% and 98 to 100%, and those of the IgG avidity SIAs were 92 to 100% and 95 to 100%, respectively. Kappa efficiency values between the SIAs and the corresponding reference assays were 0.91 to 1. Furthermore, with another panel comprising 391 clinical samples from individuals with primary infection by B19, HCMV, or T. gondii, the IgM SIAs were highly sensitive for the detection of acute infections, and the IgG avidity SIAs were highly specific for the separation of primary infections from past immunity. Altogether, the strategy of IgM multiplex screening followed by IgG avidity reflex testing can provide high-throughput and accurate means for the detection and stage determination of B19, HCMV, and T. gondii infections. IMPORTANCE Human parvovirus B19, human cytomegalovirus, and Toxoplasma gondii are ubiquitous pathogens. Their infections are often asymptomatic or mild in the general population yet may be transmitted from mother to fetus during pregnancy. Maternal infections by these pathogens can cause severe complications to the fetus or congenital abnormalities. As a rule, the risk of maternal transmission is critically related to the infection time; hence, it is important to determine when a pregnant woman has acquired the infection. In this study, we developed new diagnostic approaches for the timing of infections by three pathogens. All the new assays appeared to be highly sensitive and specific, providing powerful tools for medical diagnosis.

The avidity index (AI) of IgG to the RBD of SARS-CoV-2 was determined for 71 patients with a mild (outpatient) course of COVID-19, including 39 primarily and 36 secondarily reinfected, and 92 patients with a severe (hospital) course of COVID-19, including 82 primarily and 10 secondarily infected. The AI was shown to correlate with the severity of repeated disease. In the group of outpatients with a mild course, the reinfected patients had significantly higher median AIs than those with primary infections (82.3% vs. 37.1%, p < 0.0001). At the same time, in patients with a severe course of COVID-19, reinfected patients still had low-avidity antibodies (median AI of 28.4% vs. 25% in the primarily infected, difference not significant, p > 0.05). This suggests that the presence of low-avidity IgG to RBD during reinfection is a negative prognostic factor, in which a patient’s risk of developing COVID-19 in a severe form is significantly increased. Thus, patients with IgG of low avidity (AI ≤ 40%) had an 89 ± 20.5% chance of a severe course of recurrent COVID-19, whereas the detection of high-avidity antibodies (AI ≥ 50%) gave a probability of 94 ± 7.9% for a mild course of recurrent disease (p < 0.05).

Background and aims: Toxoplasmosis is a very common disease in the world. Two types of acquired toxoplasmosis have been detected. In the chronic toxoplasmosis, the abnormality of tissue function is little but, in acute toxoplasmosis, function of RES system becomes interrupted. The assessment of toxoplasma antibody with tissue enzymes in this stage is very important. Furthermore, serum ferritin in some conditions became high in acute phase of infectious disease. Methods: This study was based on comparative abundance study. Materials consisted of 980 serum and amniotic fluid samples collected from human blood with high level of IgG antibody against Toxoplasma gondii in Rajaie center, Tehran, Iran. The standard test was ELISA assay to detect these antibodies and the main test was measurement of liver transaminases (SGOT, SGPT) bilirubin and ferritin to evaluate acute toxoplasmosis. Data analysis was done by SPSS version 18.0. This study was done during March to June, 2017. Results: Results showed that in some patients with high level of IgG AVIDITY antibody against T. gondii the level of liver transaminases, serum bilirubin and ferritin became increased. For example in 120 patients with acute toxoplasmosis the mean serum levels of SGOT were 108 IU/L and in 80 patients the mean serum bilirubin were about 5 mg/dL. Conclusion: In acute congenital toxoplasmosis, the evaluation of IgG AVIDITY was first step and then the measurement of biochemical factors such as serum transaminases, serum Bilirubin and serum Ferritin were important.

Measles is a highly infectious illness requiring herd immunity of 95% to interrupt transmission. China has not reached elimination goals despite high vaccination coverage. We estimated the population susceptibility against measles in Tianjin, China and to tailor awareness raising activities in the measles elimination plan. Age-specific measles seroprevalence was evaluated by Enzyme-Linked Immunosorbent Assay (ELISA) on 12,164 individual aged 0–44 years in 2009–2018. Measles IgG avidity testing was performed to confirm the relationship of the waning immunity after vaccination and secondary vaccination failures (SVF) on 324 confirmed measles cases in 2013–2018. 11,108 samples (91.32%) tested positive for measles IgG, 239 (1.96%) tested as equivocal and 817 (6.72%) were negative. The age distribution of measles cases in Tianjin followed a U-shaped curve and was highest for those at <8 months and again at 20–39 years which correlated closely with the age distribution of measles susceptibility based on measles IgG antibody status (r = 0.72, P < 0.001). The seropositivity rate and antibody geometric mean concentration (GMC) for the 2018 study population were significantly lower (χ 2 = 7.45, P = 0.006 and t = 12.01, P < 0.001) compared to 2009. The multivariate stepwise logistic regression analysis showed that age and region were the risk factors for both measles seropositivity rate and GMC after vaccination. The proportion of high avidity cases increased with age, being significantly higher in 75.31% of cases in patients aged 30–34 years (χ 2 = 18.04, P = 0.003). High immunization coverage in children alone will not be adequate to realizing sufficient levels of population herd immunity, particularly given that the potential susceptibility window in adult. Implementation of supplemental immunization activity (SIA) targeted to appropriate group aged 30–34 years is recommended. [ABSTRACT FROM AUTHOR]

Background: We aimed to evaluate the diagnosis of acute toxoplasmosis by IgG avidity test in pregnant women. Methods: In this cross-sectional study, 250 blood samples were collected from pregnant women with the first month of their pregnancy referring to health centers of University in Mashhad during 2016. Samples were centrifuged at 3000 rpm for 5 min for separation of serum and were kept in the -20 until use. To detection of acute and chronic toxoplasmosis, anti-Toxoplasma antibodies (IgG and IgM, and IgG avidity tests were performed using ELISA. Then, data analyzed using SPSS software by Frequency, Pearson Chi-Square, Likelihood Ratio, and Exact tests. And P

• IgM and IgG avidity are not always reliable for diagnosis of primary HCMV infections. • Anti-p52 IgM and anti-gB IgG provide additional tools in dating HCMV infections. • Combination of different assays improves diagnosis and dating of HCMV infections. Dating of primary human cytomegalovirus (HCMV) infection in pregnancy is crucial to define whether infection occurred before or during pregnancy and at which gestational age. The aim of this study was to identify a diagnostic strategy for determination of early, intermediate and late phase of HCMV primary infection during pregnancy. Sequential serum samples from 40 pregnant women with defined onset of HCMV primary infection were tested retrospectively for IgM, IgG and IgG avidity against whole HCMV lysate, along with anti-p52 IgM and anti-gB IgG (Euroimmun AG). Anti-HCMV IgM were positive in all samples collected within the first 2 months, then decreased remaining weakly positive in about 40% of samples collected within 6–12 months after infection. Anti-p52 IgM followed similar kinetics but decreased earlier, remaining weakly positive only in 20% of late samples. Anti-HCMV IgG were positive in all samples and showed variable kinetics. Their avidity increased from low levels, observed within 2 months, to intermediate/high levels from 4 months onwards. Anti-gB IgG increased over time following kinetics similar to anti-HCMV IgG avidity. By combining results of anti-HCMV IgM plus IgG avidity, and confirming them with anti-p52 IgM plus anti-gB IgG as second-line assays, the early (within 2–3 months) and late (after 3 months) phases of HCMV infection were satisfactorily defined, whereas the intermediate phase overlapped with the beginning of the late phase. Anti-p52 IgM and anti-gB IgG provide additional tools besides classical anti-HCMV IgM, IgG and IgG avidity in dating HCMV primary infections. [ABSTRACT FROM AUTHOR]

To identify measles vaccine failures in Tianjin, China using a measles virus IgG avidity assay. The China Information System for Disease Control and Prevention (CISDCP) was used to collect information about measles cases and blood specimens in Tianjin from 2013 to 2015. Measles-specific IgM and IgG antibodies were detected using Enzyme-Linked Immunosorbent Assay (ELISA). Avidity testing for measles IgG was performed using a commercial enzyme immunoassay (EIA). A total of 284 confirmed measles cases were identified. Of this total, 262 (92.25%) were in patients aged ≥ 20 years. High avidity was exhibited in 172 (60.56%) cases, while 80 (28.17%) cases demonstrated low avidity. High avidity was detected in only 21.43% of cases in patients aged < 1 year. The proportion of high avidity increased with age, and was significantly higher in patients aged 30–39 years at 70.07% (χ 2 = 17.27, P = 0.002). Of the 52 measles cases in patients with a history of vaccinations, 41 (78.85%) cases showed high avidity, indicating secondary vaccine failures (SVF). In these vaccinations, there was no significant difference (P > 0.05) in clinical severity between high avidity and low avidity cases. However, regardless of vaccination status, clinical severity was significantly lower in high avidity cases (P < 0.001) than in low avidity cases. The percentages of positive measles IgM results in high avidity and low avidity cases were 66.28% and 91.25%, respectively. Geometric Mean Concentration (GMC) was significantly lower in high avidity cases at 33.73 U/mL, compared to 166.07 U/mL in low avidity cases. Low clinical severity and inconclusive IgM antibody results are more likely in high avidity measles cases. Measles cases were more common in adults. Therefore, a further dose of vaccines should be recommended for 30–39 years in Tianjin. [ABSTRACT FROM AUTHOR]

Background: Toxoplasma gondii is one of the major causes of abortion in pregnant women. Most cases of abortion occur in the acute phase of infection and early pregnancy. The purpose of this study was to investigate the association between spontaneous abortion and seropositive status of toxoplasmosis in women with first-time spontaneous abortion. Materials and Methods: This research is a case-control study on 240 serum samples from women experiencing spontaneous abortion for the first time as the case group, and 240 serum samples from women who had a normal delivery with no history of abortion as the control group. The level of anti-Toxoplasma gondii IgM and IgG antibodies were assessed in serum samples using ELISA. To separate the acute and chronic infections, all IgM-positive samples in both groups and IgG-positive samples of the case group were examined using IgG avidity. Results: The Toxoplasma IgM antibody was detected in 3.3% (8/240) of the case group and 0.4% (1/240) of the control group, which was a statistically significant difference between the two groups [P=0.019, odds ratio (OR)=10.266]. Of all samples 47.5% and 46.3% of the case and control groups were positive for Toxoplasma IgG antibody, respectively. Seven out of 8 (87.5%) IgM-positive serum samples from the case group had low IgG avidity, indicating acute infections, whereas all IgG-positive sera and 1 IgM-positive serum, which was related to the control group, showed a high IgG avidity, indicating chronic infections. Conclusion: Maternal acute toxoplasmosis during pregnancy is raised as one of the factors that increase the chance of spontaneous abortion. The necessary health training, especially on the parasite transmission ways to women before marriage, as well as the serological test in women before and during pregnancy is recommended. Polymerase chain reaction (PCR) and IgG avidity assays should be performed in the medical diagnostic laboratories for accurate distinguishing of the initial infection of toxoplasmosis in the pregnant women. [ABSTRACT FROM AUTHOR]

Background: We aimed to evaluate the diagnosis of acute toxoplasmosis by IgG avidity test in pregnant women. Methods: In this cross-sectional study, 250 blood samples were collected from pregnant women with the first month of their pregnancy referring to health centers of University in Mashhad during 2016. Samples were centrifuged at 3000 rpm for 5 min for separation of serum and were kept in the -20 until use. To detection of acute and chronic toxoplasmosis, anti-Toxoplasma antibodies (IgG and IgM, and IgG avidity tests were performed using ELISA. Then, data analyzed using SPSS software by Frequency, Pearson Chi-Square, Likelihood Ratio, and Exact tests. And P<0.05 was statistically considered as significant. Results: Total prevalence of IgG and IgM was 23.2% and 7.2%, respectively. A significant correlation was observed between the mean age and IgG level (P<0.05). It was not found any correlation between the history of raw meat consumption, cats keeping, education, and residency site. Moreover, 16 people (6.4%) had IgM antibody, of which, 10 cases (62.5%) with low avidity for IgG and 1 people (6.2%) with moderate avidity and 5 cases (31.3%) with high avidity for IgG. Moreover, 76% of pregnant women were seronegative. Conclusion: More than half of the women (62.5%) with positive IgM antibody in their serum had a low avidity for IgG which revealed an acute infection among pregnant women. Toxoplasma infection should be considered as an important factor that affects the pregnancy and IgG avidity as an important test for screening the women who need the treatment. [ABSTRACT FROM AUTHOR]

Toxoplasmosis, one of the most common parasitic infections, can cause abortions in human. The purpose of this study was to determine seroprevalence of toxoplasmosis and acute form of toxoplasmosis in pregnant women. 208 pregnant women who referred to health centers in south-eastern Iran were taken under study after signing the informed consent forms and filling out the checklists. For those with high levels of IgG or IgM antibody titers, IgG Avidity test was performed to determine the acute infection. High level of IgG anti-body were found in sera of 81 pregnant women and 7 persons had borderline titer. IgM antibody results were positive in 33 and borderline in 4 cases. Then, the samples with positive and borderline results for IgM and IgG were evaluated by IgG avidity test. In this study, approximately 60% of pregnant women were not immune to risks posed by Toxoplasma gondii. Therefore, this group are at risk of acquiring primary infection of toxoplasmosis during gestation. [ABSTRACT FROM AUTHOR]

Primary infection with Toxoplasma gondii (T. gondii) during pregnancy may cause congenital infection of the infant. This study evaluated whether screening using IgG avidity and multiplex-nested polymerase chain reaction (PCR) methods was effective for detecting a high-risk pregnancy for congenital T. gondii infection. In a prospective cohort study serum T. gondii IgG avidity was measured in 469 pregnant women who had a positive test for T. gondii antibody plus a positive or equivocal test for IgM. Multiplex-nested PCR for T. gondii DNA on amniotic fluid, maternal blood, and neonatal blood was performed with informed consent. Low (<30%), borderline (30–35%), and high (>35%) IgG avidity indices were found in 104 (22.2%), 30 (6.4%), and 305 (71.4%), respectively. A total of 12 cases had a positive PCR test for amniotic fluids of the prenatal amniocentesis or at birth, or neonatal blood. Seven of the 12 cases were diagnosed as having congenital T. gondii infection, and they had low IgG avidity indices. Congenital T. gondii infection screening using of IgG avidity and multiplex-nested PCR methods for pregnant women with a positive test for T. gondii antibody plus a positive or equivocal test for T. gondii IgM was useful for detecting a high-risk pregnancy and diagnosing congenital T. gondii infection. [ABSTRACT FROM AUTHOR]

Primary infection occurs when seronegative women are infected by human cytomegalovirus (HCMV). Diagnosis of primary infection is based on the following: antibody seroconversion, presence of IgM and low IgG avidity index (AI), and presence of DNAemia. The kinetics of HCMV-specific IgM antibody and maturation of AI might be very rapid or long-lasting during primary infection, which makes serological diagnosis insidious. The aims of this study were as follows: (i) to report atypical kinetics of HCMV-specific IgM antibody and AI early after onset of primary HCMV infection in a population of pregnant women, and (ii) to assess the frequency of such results. Altogether, 1309 sequential serum samples collected from 465 pregnant women with primary HCMV infection were included in the study. As a general rule, using the LIAISON®CMVIgMII and LIAISON®CMVIgGAvidityII assays, virus-specific IgM antibody levels decreased, while IgG AI increased over time during the first three months after infection onset. However, early clearance of IgM antibody and/or early IgG AI maturation occurred in 46/426 (10.7%) women. In more details, 20/426 (4.7%) and 26/418 (6.2%) women had undetectable IgM antibody or high IgG AI, respectively, when tested within 1–3 months after well-defined infection onset. Twenty sera from as many women with high IgG AI by the LIAISON assay were further tested for IgG AI by VIDAS®CMVIgGAvidityII and Mikrogen recomLineCMVIgG Avidity assays. Comparable results were obtained with VIDAS, whereas 14/20 sera gave low AI with the Mikrogen assay. In conclusion, about 11% of pregnant women undergoing a primary HCMV infection showed misleading serological results. Additional and appropriate testing might help in reducing the risk of missing HCMV primary infection in pregnancy. Furthermore, preconceptional testing should be strongly recommended.

Highlights • Biomarkers of clinical disease are useful in prophylaxis and therapeutics CVL. • Multivariate regression identified important markers, especially the avidity index. • IgG avidity index was also strongly correlated with the number of clinical signs. Abstract Canine visceral leishmaniosis (CVL), a parasitic disease caused by Leishmania infantum , may evolve to a chronic condition and lead to death. Evaluation of infected dogs is important to establish the clinical and laboratory parameters involved in the evolution of the disease. The objectives of the present study were to discriminate a canine population (n = 52) into sub-clinical and clinically affected dogs based on signs and scores, to evaluate the hematological, biochemical, histopathological and parasitological parameters of the two dog groups, and to analyze the results by multivariate regression analysis with the aim of establishing biomarkers of CVL clinical disease. The most common signs observed in the clinically affected dogs (n = 29) were hyperkeratosis, weight loss, onychogryphosis, pale mucosa and lymphadenomegaly. In the multivariate analysis, animals presenting high IgG avidity index and low red blood, lymphocyte and eosinophil counts, and low serum urea concentration had an increased probability of being classified as clinically affected (p < 0.05). All five parameters were considered to be strong biomarkers for monitoring the clinical disease, while IgG avidity percentage was strongly correlated with the number of clinical signs and could function as an indicator of the duration of infection. This is the first report on the application of IgG avidity and of multivariate regression analysis in establishing associations between the clinical signs of CVL and host biomarkers. Since avidity index (AI) percentages were strongly correlated with the number of clinical signs, it could be useful in clinical practice for auxiliary diagnosis of CVL and monitoring disease progression. A limitation of this study is the lack of information on co-infections by Anaplasma platys , Babesia canis vogeli , Ehrlichia canis and Hepatozoon canis. Therefore future studies should evaluate the influence of such co-infections on the associations studied using multivariate methods with larger samples. [ABSTRACT FROM AUTHOR]

Background and objectives The mechanisms leading to low effectiveness of the humoral immune response against P. aeruginosa in cystic fibrosis (CF) are poorly understood. The aim of the present study was to assess the avidity maturation of specific antipseudomonal IgG before and during the development of chronic lung infection in a cohort of Danish CF patients. Methods Avidity maturation was assessed against a pooled P. aeruginosa antigen (St-Ag) and against P. aeruginosa alginate in 10 CF patients who developed chronic lung infection and 10 patients who developed intermittent lung colonization, using an ELISA technique with the thiocyanate elution method. Avidity was quantitatively determined by calculating the avidity Constant (Kav). Results IgG avidity to St-Ag significantly increased at the onset (Median Kav = 2.47) and one year after the onset of chronic infection (Median Kav = 3.27), but did not significantly changed in patients who developed intermittent colonization. IgG avidity against alginate did not significantly change over the years neither in patients who developed chronic lung infection (Median Kav = 3.84 at the onset of chronic infection), nor in patients who developed intermittent colonization. Conclusion IgG avidity to P. aeruginosa alginate does not significantly enhance as chronic lung infection progresses. This probably plays a role in the difficulty to mount an effective opsonophagocytic killing to clear mucoid P. aeruginosa infection in CF. [ABSTRACT FROM AUTHOR]

This prospective study was aimed to detect acute and chronic ocular toxoplasmosis by comparison of anti- Toxoplasma gondii IgM and IgG antibody levels and IgG avidity test. One hundred and seventeen patients with ocular toxoplasmosis (OT) who referred to the Farabi Eye Hospital, Tehran, Iran were included in this study. Of the patients, 77 cases were positive for anti-T. gondii IgG, and 8 cases were positive for anti-T. gondii IgM. IgG avidity test revealed 11, 4, and 102 cases were low, intermediate, and high, respectively, and 6.8% and 9.4% of cases were positive for IgM and IgG avidity tests, respectively (P=0.632). Agreement (Kappa value) between paired tests IgG-IgM, IgG-IgG avidity, and IgMIgG avidity was 0.080, 0.099, and 0.721, respectively (P<0.05). This study showed that conventional serologic tests (IgM and IgG levels) and IgG avidity correlate well each other and can be used to differentiate recent infections from old OT. It seems that reactivated old infections rather than recently acquired infections are majority of Iranian OT patients. [ABSTRACT FROM AUTHOR]