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Mansonella ozzardi, a filarioid parasite, causes human mansonellosis in the Americas. We identified raccoons (Procyon lotor) as wildlife reservoirs of M. ozzardi in Costa Rica. Noting the sympatry of free-ranging raccoons and humans, we conclude that mansonellosis is a considerable public health risk in the region.

Mansonella spp. have been reported to have a wide global distribution. Despite the distribution and co-occurrence with other filarial parasites like Wuchereria bancrofti, Onchocerca volvulus and Loa loa, it is given little attention. There are few surveillance programmes for assessing the distribution of mansonellosis, due to the associated mild to no symptoms experienced by infected people. However, addressing this infection is critical to the onchocerciasis control program as current rapid diagnostic tools targeting O. volvulus have the tendency to cross react with Mansonella species. In this study we identified and characterised M. perstans from five sites in two districts in the Volta Region of Ghana and compared them to samples from other regions. Night blood smears and filter blood blots were obtained from individuals as part of a study on lymphatic filariasis. The Giemsa-stained smears were screened by microscopy for the presence of filarial parasites. Genomic DNA was extracted from blood blots from 39 individuals that were positive for M. perstans and Nested PCR targeting the internal spacer 1 (ITS-1) was conducted. Of these, 30 were sequenced and 24 sequences were kept for further analysis. Phylogenetic analysis of 194 nucleotide positions showed no differences in the samples collected. The similarities suggests that there could be one species in this area. However, more robust studies with larger sample sizes are required to draw such conclusions. We also observed a clustering of the samples from Ghana with reference sequences from Africa and Brazil, suggesting they could be related. This study draws further attention to a neglected infection, presents the first characterisation of M. perstans in Ghana and calls for more population-based studies across different geographical zones to ascertain species variations and disease distribution., Competing Interests: The authors have declared that no competing interest exist., (Copyright: © 2024 Opoku, de Souza. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Mansonellosis is an undermapped insect-transmitted disease caused by filarial nematodes that are estimated to infect hundreds of millions of people. Despite their prevalence, there are many outstanding questions regarding the general biology and health impacts of the responsible parasites. Historical reports suggest that the Colombian Amazon is endemic for mansonellosis and may serve as an ideal location to pursue these questions., Methods: We deployed molecular and classical approaches to survey Mansonella prevalence among adults belonging to indigenous communities along the Amazon River and its tributaries near Leticia, Colombia., Results: Loop-mediated isothermal amplification (LAMP) assays on whole-blood samples detected a much higher prevalence of Mansonella ozzardi infection (approximately 40%) compared to blood smear microscopy or LAMP performed using plasma, likely reflecting greater sensitivity and the ability to detect low microfilaremias and occult infections. Mansonella infection rates increased with age and were higher among men. Genomic analysis confirmed the presence of M. ozzardi that clusters closely with strains sequenced in neighboring countries. We successfully cryopreserved M. ozzardi microfilariae, advancing the prospects of rearing infective larvae in controlled settings., Conclusion: These data suggest an underestimation of true mansonellosis prevalence, and we expect that these methods will help facilitate the study of mansonellosis in endemic and laboratory settings., Competing Interests: Potential conflicts of interest. C. K. S. C., Z. L., A. S., and S. R. are employed by New England Biolabs, a manufacturer and vendor of molecular biology reagents. All other authors report no potential conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Life-style metabolic diseases are steadily rising, not only in developed countries, but also in low- and middle-income countries, presenting a global health problem. Metabolic disorders like type 2 diabetes and cardiovascular diseases are among the ten leading causes of death defined by the WHO in 2019. Results from animal and observational human studies suggest a connection between the decline in human helminth infections and rise of life-style-associated metabolic diseases in developing regions. This trial was designed to investigate filarial infections and their impact on metabolic diseases in Cameroon. We hypothesize that the induction of regulatory immune responses during filarial infection reduces obesity-induced low-grade inflammatory immune responses and thereby improves metabolic parameters, whereas anthelmintic treatment abolishes this protective effect., Methods/design: Participants infected with Mansonella perstans, Onchocerca volvulus and/or Loa loa being lean (BMI <25), overweight (BMI >25 and <30) or clinically obese (BMI ≥30) from Littoral regions of Cameroon will be evaluated for their parasitological, immunological, metabolic and biochemical profile before and after treatment of their parasitic infections. Anthropomorphic measurements and a detailed questionnaire will complement our analysis. The investigation will assess blood immune cell populations, serum adipokines and cytokines that could be influenced by the parasite infection and/or metabolic diseases. Further, parameters like blood glucose, homeostatic model assessment of insulin resistance (HOMA-IR), circulating lipids and circulating makers of liver function will be monitored. Parameters will be assessed before treatment, 12 and 18 months after treatment., Conclusion: The focus of this study is to obtain a comprehensive metabolic profile of the participants in rural areas of Cameroon and to investigate the relationship between filarial immunomodulation and metabolic diseases. This study will elucidate the effect of anti-filarial treatment on the metabolic and immunological parameters that partake in the development of insulin resistance, narrowing in on a potential protective effect of filarial infections on metabolic diseases., Trial Registration: doi.org/10.1186/ISRCTN43845142, ISRCTN43845142 February 2020 Trial title Effects of filarial parasite infection on type 2 diabetes Issue date: 27.10.22, V.1., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Lenz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objectives: Loa loa and Mansonella perstans are two very common filarial species in Africa. Although microscopy is the traditional diagnostic method for human filariasis, several polymerase chain reaction (PCR) methods have emerged as an alternative approach for identifying filarial parasites. The aim of this study is to compare three molecular methods and decide which is the most suitable for diagnosing human loiasis and mansonellosis in non-endemic regions using dried blood spot (DBS) as a medium for sample collection and storage., Methods: A total of 100 DBS samples, with their corresponding thin and thick blood smears, were selected for this study. Microscopy was used as the reference method to diagnose and calculate the microfilaraemia. Filarial DNA was extracted using the saponin/Chelex method and the DNA isolated was assayed by Filaria-real time-PCR, filaria-nested PCR, and cytochrome oxidase I PCR. All PCR products were subsequently purified and sequenced. The statistical values for each molecular test were calculated and compared., Results: Overall, 64 samples were identified as negative by all tests and a further 36 samples were positive by at least one of the methods used. The sensitivity and specificity were similar for the different molecular methods, all of which demonstrated good agreement with microscopy., Conclusions: Based on this study, and from a practical point of view (single and short amplification round), the optimal technique for diagnosing filarial infection in non-endemic regions is filaria-real time-PCR, which presents high sensitivity and specificity and is also able to detect a wide range of human filariae., (© 2022 John Wiley & Sons Ltd.)

Objective: To assess the emergent zoonotic disease risk posed by the voracious human-biting blackfly species Simulium oyapockense in the peripheral regions of an expanding urban centre situated deep in the Brazilian Amazon rainforest., Methods: We performed nine human landing catches at three periurban sites surrounding the Brazilian Amazon town of São Gabriel da Cachoeira. Using the detection of non-human primate filarial parasites as an indicator of the zoonotic disease threat posed by a biting insect, we screened 3328 S. oyapockense blackflies for the presence of zoonotic filarial DNA with an ITS-1 PCR assay and Sanger sequencing., Results: Between 98 and 100% of the biting insects captured during our nine collections were identified as S. oyapockense; at our three collection sites and during our three seasonally-distinct collections this species was captured at rates between 28 and 294 blackflies per hour. PCR screening of the march-collected S. oyapockense detected infectious-stage (L3) Mansonella mariae parasites (which are only known to infect non-human primates) in >0.15% of the tested head samples., Conclusions: Our results show that residents of the periurban regions of São Gabriel da Cachoeira are routinely exposed to the bites of S. oyapockense blackflies which have previously fed on non-human primates., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Loa loa and Mansonella perstans-the causative agents of loiasis and mansonellosis-are vector-borne filarial parasites co-endemic in sub-Saharan Africa. Diagnosis of both infections is usually established by microscopic analysis of blood samples. It was recently established that the odds for detecting Plasmodium spp. is higher in capillary (CAP) blood than in venous (VEN) blood. In analogy to this finding this analysis evaluates potential differences in microfilaraemia of L. loa and M. perstans in samples of CAP and VEN blood., Methods: Recruitment took place between 2015 and 2019 at the CERMEL in Lambaréné, Gabon and its surrounding villages. Persons of all ages presenting to diagnostic services of the research center around noon were invited to participate in the study. A thick smear of each 10 microliters of CAP and VEN blood was prepared and analysed by a minimum of two independent microscopists. Differences of log2-transformed CAP and VEN microfilaraemia were computed and expressed as percentages. Furthermore, odds ratios for paired data were computed to quantify the odds to detect microfilariae in CAP blood versus in VEN blood., Results: A total of 713 participants were recruited among whom 52% were below 30 years of age, 27% between 30-59 years of age and 21% above 60 years of age. Male-female ratio was 0.84. Among 152 participants with microscopically-confirmed L. loa infection median (IQR) microfilaraemia was 3,650 (275-11,100) per milliliter blood in CAP blood and 2,775 (200-8,875) in VEN blood (p<0.0001), while among 102 participants with M. perstans this was 100 (0-200) and 100 (0-200), respectively (p = 0.44). Differences in linear models amount up to an average of +34.5% (95% CI: +11.0 to +63.0) higher L. loa microfilaria quantity in CAP blood versus VEN blood and for M. perstans it was on average higher by +24.8% (95% CI: +0.0 to +60.5). Concordantly, the odds for detection of microfilaraemia in CAP samples versus VEN samples was 1.24 (95% CI: 0.65-2.34) and 1.65 (95% CI: 1.0-2.68) for infections with L. loa and M. perstans, respectively., Conclusion: This analysis indicates that average levels of microfilaraemia of L. loa are higher in CAP blood samples than in VEN blood samples. This might have implications for treatment algorithms of onchocerciasis and loiasis, in which exact quantification of L. loa microfilaraemia is of importance. Furthermore, the odds for detection of M. perstans microfilariae was higher in CAP than in VEN blood which may pre-dispose CAP blood for detection of M. perstans infection in large epidemiological studies when sampling of large blood quantities is not feasible. No solid evidence for a higher odds of L. loa microfilariae detection in CAP blood was revealed, which might be explained by generally high levels of L. loa microfilaraemia in CAP and VEN blood above the limit of detection of 100 microfilariae/ml. Yet, it cannot be excluded that the study was underpowered to detect a moderate difference., Competing Interests: The authors have declared that no competing interests exist.

Mansonella perstans, a filarial nematode, infects large populations in Africa and Latin America. Recently, a potential new species, Mansonella sp "DEUX," was reported. Carriage of endosymbiotic Wolbachia opens treatment options for Mansonella infections. Within a cross-sectional study, we assessed the prevalence of filarial infections in 834 Gabonese individuals and the presence of the endosymbiont Wolbachia. Almost half of the participants (400/834 [48%]) were infected with filarial nematodes, with Mansonella sp "DEUX" being the most frequent (295/400 [74%]), followed by Loa loa (273/400 [68%]) and Mansonella perstans (82/400 [21%]). Being adult/elderly, male, and living in rural areas was associated with a higher risk of infection. Wolbachia carriage was confirmed in M. perstans and Mansonella sp "DEUX." In silico analysis revealed that Mansonella sp "DEUX" is not detected with currently published M. perstans-specific assays. Mansonella infections are highly prevalent in Gabon and might have been underreported, likely also beyond Gabon., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

We reviewed Giemsa-stained thick blood smears, obtained through the national malaria surveillance program in the Amazon region of Ecuador, by light microscopy for Mansonella spp. microfilariae. Of 2,756 slides examined, 566 (20.5%) were positive. Nested PCR confirmed that the microfilariae were those of M. ozzardi nematodes, indicating that this parasite is endemic to this region.

Background: In the Brazilian Amazon, the filarial nematode Mansonella ozzardi co-exists with malaria parasites and thick blood smear microscopy is considered the diagnostic gold standard. Transfusion of M. ozzardi microfilariae does not establish new infections, however microfilariae can survive approximately 2 years in blood-recipients with unknown risk of pathology. Data on transfusion-transmitted filariasis are lacking. This study investigated M. ozzardi parasitemias in blood donors from decentralized centers of "Fundação Hematologia e Hemoterapia do Estado do Amazonas/HEMOAM," Northern Brazil., Study Design and Methods: Cross-sectional investigation employing blood smear microscopy (n = 356) and qualitative nested-M. ozzardi-PCR (227 out of 356) in donor candidates from 19 hemocenters in interior/rural municipalities of Amazonas state., Findings: Participants were mostly young males. Positivity by microscopy was 7.9% (28 out of 356) and 23.8% by M. ozzardi-PCR (54 out of 227). Parasitaemias were found in 16 out of 19 municipalities. In 54 M. ozzardi-positives, 24 were ineligible; among 30 that donated, 27 were interdicted by seropositivity (22 anti-HBc, 3 anti-HBc + HBsAg, 1 Chagas+malaria, 1 VDRL). Seropositivty was higher in M. ozzardi-PCR-positives vs M. ozzardi-PCR-negatives (OR = 15.8, 95% CI 4.5-56.1, p < 0.0001). Three M. ozzardi contaminated blood units were transfused, but no follow-up information on the recipients is available., Main Conclusions: Our study provides important baseline data on M. ozzardi among blood donors from the Brazilian Amazon. Further investigations in endemic areas are necessary to clarify possible association between M. ozzardi and other infections and also to elucidate whether there is any significant clinical effect upon transfusion of contaminated blood., (© 2018 AABB.)

Despite the broad distribution of M. ozzardi in Latin America and the Caribbean, there is still very little DNA sequence data available to study this neglected parasite's epidemiology. Mitochondrial DNA (mtDNA) sequences, especially the cytochrome oxidase (CO1) gene's barcoding region, have been targeted successfully for filarial diagnostics and for epidemiological, ecological and evolutionary studies. MtDNA-based studies can, however, be compromised by unrecognised mitochondrial pseudogenes, such as Numts. Here, we have used shot-gun Illumina-HiSeq sequencing to recover the first complete Mansonella genus mitogenome and to identify several mitochondrial-origin pseudogenes. Mitogenome phylogenetic analysis placed M. ozzardi in the Onchocercidae "ONC5" clade and suggested that Mansonella parasites are more closely related to Wuchereria and Brugia genera parasites than they are to Loa genus parasites. DNA sequence alignments, BLAST searches and conceptual translations have been used to compliment phylogenetic analysis showing that M. ozzardi from the Amazon and Caribbean regions are near-identical and that previously reported Peruvian M. ozzardi CO1 reference sequences are probably of pseudogene origin. In addition to adding a much-needed resource to the Mansonella genus's molecular tool-kit and providing evidence that some M. ozzardi CO1 sequence deposits are pseudogenes, our results suggest that all Neotropical M. ozzardi parasites are closely related.

Human filariae are vector-borne parasites and the causative agents of various diseases, including human onchocerciasis and lymphatic filariasis. Onchocerciasis causes a spectrum of cutaneous and ophthalmologic manifestations (including blindness) and has long been a major public health problem in Bioko Island (Equatorial Guinea). Bioko Island has been included in the WHO's Onchocerciasis Control Program since 1987. In Bioko Island, the specificity and sensitivity of clinical Onchocerca volvulus diagnosis is key. The objective of this work was to update onchocerciasis elimination progress in Bioko Island, after 18 years of mass ivermectin intervention, and the general filariasis situation through a rapid and accurate molecular method. A cross-sectional study was conducted in Bioko Island from mid-January to mid-February 2014. A total of 543 subjects were included in the study. Whole blood and one skin snip (from lumbar regions) were analysed with a real time PCR assay. Two other skin biopsies were analysed by an expert microscopist. All positive samples were confirmed by sequencing. Traditional microscopic examination of the skin biopsies failed to detect any microfilariae. However, 11 (2.03%) infections were detected using PCR assay, including one O. volvulus, two Mansonella streptocerca, seven Mansonella perstans and one Loa loa infections. PCR assays in blood detected 52 filariae-positive individuals (9.6%) which harboured M. perstans or L. loa. The low prevalence of O. volvulus confirms the success of the Onchocerciasis Control Programme and suggests that Mass Drug Administration in Bioko Island can be interrupted in the near future. The very high prevalence of M. perstans found in skin snips assays raises doubts about the reliability of microscope-based diagnosis of O. volvulus infections., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The treatment of mansonelliasis is still a challenge because there are few clinical trials for the treatment of the disease. This double-blind, randomized, placebo-controlled study (phase III clinical trial) was conducted to evaluate the effectiveness of a single oral dose of ivermectin (0.15 mg/kg) in the reduction of the Mansonella ozzardi microfilaraemia and the occurrence of adverse effects in infected people compared with the control group treated with placebo. A total of 49 microfilaraemic patients were randomly selected from the municipality of Lábrea, State of Amazonas, in the Brazilian Amazon. Among them, 40 patients have concluded the study, 19 treated with ivermectin and 21 treated with placebo. In the first and third days after the treatment, all the patients were clinically evaluated, and the diagnostic and quantification of blood microfilariae through blood filtration in polycarbonate membranes was performed. A significant reduction of the microfilaraemia (99.9%) was observed in the patients who received ivermectin. Slight changes in laboratory test results, without clinical importance, were seen in treated and control groups. Our results suggest that ivermectin is effective and safe for the treatment of infections caused by M. ozzardi .

Background: Approximately 114 million people are infected with Mansonella perstans in large proportions of Africa. In contrast to other filariae that infect humans, M. perstans-infected individuals show no distinct pathology or specific clinical picture, indicating a well-tuned adaptation to the host. In addition, since M. perstans adult worms reside in serous cavities which are difficult to access, research has been hindered and there is a paucity of knowledge about the biology of M. perstans, especially the development of the different life stages as well as M. perstans-driven immune responses. Thus in this study, an in vitro culture system was developed which allows an in-depth analysis of M. perstans., Results: Culicoides species were caught in Ediki (Kumba), Southwest Region within Cameroon following a blood meal on a microfilaremic donor that had 1500 microfilariae/ml of peripheral blood and kept in captivity for 12 days at 23 °C. In a pilot experiment, 15 infective larvae were obtained from the midges and co-cultured with a confluent monolayer of monkey kidney epithelial cells (LLC-MK2) in DMEM medium supplemented with 10% FBS for up to 77 days. The resulting survival rates of 33% revealed that the cell-conditioned medium was suitable for long-term maintenance of M. perstans worms. To confirm these preliminary observations, 249 infective larvae were cultured for 50 days and their development was monitored daily and microscopically graded for motility. In total, 170 (68.3%) filariae survived and 124 (49.8%) larvae moulted between days 21-30 to become L5 stage larvae which were motile and showed continuous vigorous movement., Conclusion: We have established an in vitro culture system for the generation and long-term maintenance of viable M. perstans worms. This technique will be an important tool to study parasite biology and development, the role in host immunity, and might be helpful to discover novel treatment strategies against this filariae.

We report 74 patients in Italy infected with Mansonella perstans nematodes, a poorly described filarial parasite. M. perstans nematodes should be included in the differential diagnosis for patients with eosinophilia from disease-endemic countries. Serologic analysis is useful for screening, and testing for microfilaremia in peripheral blood should be performed for parasite-positive patients.

We obtained ribosomal and mitochondrial DNA sequences from residents of Amazonas state, Brazil, with Mansonella parasitemias. Phylogenetic analysis of these sequences confirm that M. ozzardi and M. perstans parasites occur in sympatry and reveal the close relationship between M. perstans in Africa and Brazil, providing insights into the parasite's New World origins.

Mansonellosis is endemic in several regions of Africa, the Caribbean, and Latin America. Mansonella ozzardi and Mansonella perstans have been reported in Latin America, including the Amazon region. A morphological and molecular microfilariae study was performed in Pauini (Brazil). Blood samples were collected from 40 individuals, and were analyzed by Giemsa-stained blood film and by two different nested polymerase chain reactions which detect internal transcribed spacer-1 and the major sperm protein gene. By microscopy, 14 of 40 were positive: 11 as M. ozzardi and three as M. perstans-like infections. Both molecular methods detected 19 positive cases as M. ozzardi, including those 14 individuals detected by microscopy, without detectable genetic differences among any of the 19 positive samples. Molecular techniques showed an improvement of mansonellosis diagnosis and may become an effective tool to evaluate the present status of M. ozzardi and M. perstans in Latin America., (© The American Society of Tropical Medicine and Hygiene.)

The relationship between the frequency of loiasis objective symptoms and microfilaraemic or amicrofilaraemic infection was assessed in 1148 exposed patients also infected, or not, with Mansonella perstans. Filarial infections were detected by direct microscopy, leucoconcentration and serology, with prevalence values of 39.5% Loa loa, 5.6% M. perstans and 3.4% co-infection with both filarial species. Amicrofilaraemic or occult loiasis (OL) predominated among L. loa-infected individuals, with a prevalence of 58.2%. Hypermicrofilaraemia (>8000 microfilariae (mf)/ml) was found in 18.4% of L. loa microfilaraemic patients, with 25.7% of them harbouring more than 30,000 mf/ml. Up to 34% of patients with OL showed evidence of Calabar swelling, compared with 26.3% of microfilaraemic patients (P= 0.03). Overall 5.3% of patients presented with adult worm migration across the eye, representing 16.3% of microfilaraemic individuals and 11.4% of amicrofilaraemic patients (P= 0.13). This symptom was similarly found in patients with more than 30,000 mf/ml (22%), those with microfilaraemia between 8 and 30,000 mf/ml (15.4%) and also in individuals with low or without microfilaraemia (16.1%) (P= 0.7). Five (14.3%) hypermicrofilaraemic patients did not present any L. loa-specific objective symptoms, as well as all the patients with single M. perstans infection. The presence of adult eye worm migration as a strong predictor of high microfilaraemia density would obscure the real burden of L. loa hypermicrofilaraemia in exposed individuals. For epidemiological purposes and control strategies, the mapping of L. loa in endemic areas should also take into account the group of patients with occult loiasis.

The study of the interactions among parasites within their hosts is crucial to the understanding of epidemiology of disease and for the design of effective control strategies. We have conducted an assessment of infections with Loa loa, Mansonella perstans, Wuchereria bancrofti, and Plasmodium falciparum in eastern Cameroon using a highly sensitive and specific quantitative polymerase chain reaction assay using archived dried whole blood spots. The resident population (N = 1,085) was parasitized with M. perstans (76%), L. loa (39%), and P. falciparum (33%), but not with W. bancrofti Compared with single infections (40.1%), coinfection was more common (48.8%): 21.0% had L. loa-M. perstans (Ll(+)/Mp(+)/Pf(-)), 2.7% had L. loa-P. falciparum (Ll(+)/Pf(+)/Mp(-)), 15.1% had M. perstans-P. falciparum (Mp(+)/Pf(+)/Ll(-)), and 10.0% had L. loa-M. perstans-P. falciparum (Ll(+)/Mp(+)/Pf(+)). Interestingly, those with all three infections (Ll(+)/Mp(+)/Pf(+)) had significantly higher L. loa microfilaria (mf) counts than either single Ll(+) (P = 0.004) or double Ll(+)/Mp(+) (P = 0.024) infected individuals. Of those infected with L. loa, the mean estimated counts of L. loa mf varied based on location and were positively correlated with estimated intensities of M. perstans mf. Finally, at a community level, heavy L. loa infections were concentrated in a few individuals whereby they were likely the major reservoir for infection., (© The American Society of Tropical Medicine and Hygiene.)

Mansonella ozzardi (Nematoda: Onchocercidae) is an understudied filarial nematode, originally described by Patrick Manson in 1897, that can be transmitted by two families of dipteran vectors, biting midges (most of them members of the genus Culicoides) and black flies (genus Simulium). With a patchy geographic distribution from southern Mexico to northwestern Argentina, human infection with M. ozzardi is highly prevalent in some of the Caribbean islands, along riverine communities in the Amazon Basin, and on both sides of the border between Bolivia and Argentina. There is no clinical entity unequivocally associated with M. ozzardi infection, although fever, arthralgia, headache, cold lower extremities, and itchy cutaneous rashes are occasionally mentioned in case report series. More recently, ocular manifestations (especially keratitis) have been associated with mansonelliasis, opening an important area of investigation. Here, we briefly review the biology, epidemiology, pathogenesis, and clinical aspects of M. ozzardi infection and point to some existing knowledge gaps, aiming to stimulate a research agenda to help filling them.

Background: Mansonella perstans is a widespread, but relatively unknown human filarial parasite transmitted by Culicoides biting midges. Although it is found in many parts of sub-Saharan Africa, only few studies have been carried out to deepen the understanding of its ecology, epidemiology, and health consequences. Hence, knowledge about ecological drivers of the vector and parasite distribution, integral to develop spatially explicit models for disease prevention, control, and elimination strategies, is limited., Methodology: We analyzed data from a comprehensive nationwide survey of M. perstans infection conducted in 76 schools across Uganda in 2000-2003, to identify environmental drivers. A suite of Bayesian geostatistical regression models was fitted, and the best fitting model based on the deviance information criterion was utilized to predict M. perstans infection risk for all of Uganda. Additionally, we investigated co-infection rates and co-distribution with Wuchereria bancrofti and Plasmodium spp. infections observed at the same survey by mapping geographically overlapping areas., Principal Findings: Several bioclimatic factors were significantly associated with M. perstans infection levels. A spatial Bayesian regression model showed the best fit, with diurnal temperature range, normalized difference vegetation index, and cattle densities identified as significant covariates. This model was employed to predict M. perstans infection risk at non-sampled locations. The level of co-infection with W. bancrofti was low (0.3%), due to limited geographic overlap. However, where the two infections did overlap geographically, a positive association was found., Conclusions/significance: This study presents the first geostatistical risk map for M. perstans in Uganda. We confirmed a widespread distribution of M. perstans, and identified important potential drivers of risk. The results provide new insight about the ecologic preferences of this otherwise poorly known filarial parasite and its Culicoides vector species in Uganda, which might be relevant for other settings in sub-Saharan Africa.

Human filariasis caused by Mansonella ozzardi is a parasitic infection of a controversial pathology and poorly studied in Argentina. The aim of this study was not only to obtain data of the prevalence of M. ozzardi in Northwestern Argentina through comparison of infection rates in relation to sex and age group determining the range of distribution of mansonelliasis in the region but also to investigate the prevalence of the cases over time. Through field work carried between 1986 and 2010 by technicians of the National Ministry of Health, aiming to detect active cases of malaria in the Northwestern Argentina, blood samples were taken for smear and thick blood. 417 blood samples were examined, 381 of them (91.4%) were positive for M. ozzardi. The highest prevalence was found in Salta province (92.3%) mainly affecting the male sex (92.6%) and the age groups comprised between 48-57 years (97.0%) and ≥ 68 (90.7%). The paired t-test and Spearman coefficients showed significant differences in prevalence according to sex (t=2.677; p=0.015), and according infection rates in males and females/age (r=0.994; p=0.001; r=0.994, p=0.001, respectively). The prevalence over time showed a general pattern with the highest cases in 1986, decreasing later during the following years. Aguas Blancas, El Oculto and San Ramón de la Nueva Orán, exhibited a pattern of prevalence according to the general trend but Salvador Mazza and Tartagal, which are also localities close to the border with Bolivia, showed peaks of cases up to 2010. These results provide relevant information about M. ozzardi in Argentina, demonstrating not only its presence and endemicity after almost 100 years from its discovery in the country, but also its wide range of distribution in the region., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Mansonella ozzardi is a poorly understood human filarial parasite with a broad distribution throughout Latin America. Most of what is known about its parasitism has come from epidemiological studies that have estimated parasite incidence using light microscopy. Light microscopy can, however, miss lighter, submicroscopic, infections. In this study we have compared M. ozzardi incidence estimates made using light microscopy, with estimates made using PCR., Methods: 214 DNA extracts made from Large Volume Venous Blood Samples (LVVBS) were taken from volunteers from two study sites in the Rio Solimões region: Codajás [n = 109] and Tefé [n = 105] and were subsequently assayed for M. ozzardi parasitism using a diagnostic PCR (Mo-dPCR). Peripheral finger-prick blood samples were taken from the same individuals and used for microscopic examination. Finger-prick blood, taken from individuals from Tefé, was also used for the creation of FTAcard dried blood spots (DBS) that were subsequently subjected to Mo-dPCR., Results: Overall M. ozzardi incidence estimates made with LVVBS PCRs were 1.8 times higher than those made using microscopy (44.9% [96/214] compared with 24.3% [52/214]) and 1.5 times higher than the PCR estimates made from FTAcard DBS (48/105 versus 31/105). PCR-based detection of FTAcard DBS proved 1.3 times more sensitive at diagnosing infections from peripheral blood samples than light microscopy did: detecting 24/105 compared with 31/105. PCR of LVVBS reported the fewest number of false negatives, detecting: 44 of 52 (84.6%) individuals diagnosed by microscopy; 27 of 31 (87.1%) of those diagnosed positive from DBSs and 17 out of 18 (94.4%) of those diagnosed as positive by both alternative methodologies., Conclusions: In this study, Mo-dPCR of LVVBS was by far the most sensitive method of detecting M. ozzardi infections and detected submicroscopic infections. Mo-dPCR FTAcard DBS also provided a more sensitive test for M. ozzardi diagnosis than light microscopy based diagnosis did and thus in settings where only finger-prick assays can be carried-out, it may be a more reliable method of detection. Most existing M. ozzardi incidence estimates, which are often based on light microscope diagnosis, are likely to dramatically underestimate true M. ozzardi parasitism incidence levels.

The occurrence of Mansonella perstans was studied among people who had resided in Calabar metropolis for at least one year prior to the time of this study, which lasted from February to August, 2011. One thousand residents, comprising 530 males and 470 females, with an age range of 4 to 59 years, participated in the study, after an informed consent. Two millilitres of venous blood were collected at day time into EDTA bottles. The blood samples were processed by diluting 1ml of blood in 9 mls of 1% formalin and centrifuging the preparation at 3,000 revolutions per minute for 5 minutes. Deposits were left as blood smears on clean slides and after air-drying, were stained with 3% Giemsa solution for microscopy. Overall, the prevalence of Mansonella perstans was 2% (20 vs 1,000). The prevalence of the parasite among the females was 2.1% (10 vs 470) and males 1.9% (10 vs 530). Microfilaraemia only occurred among subjects aged between 25 and 45 years. The results of this study suggest that loiasis, which earned Calabar an unenviable mention in early medical literature, is no longer very prevalent in the area. Instead, a low prevalence of mansonelliasis occurs, in tandem with the existence of sparse farmlands of banana and plantain. Old stems of these crops provide suitable habitats for Culicoides species, which transmit Mansonella perstans.

An epidemiologic (cross-sectional study) survey on 462 inhabitants in Corail, Haiti showed that 16.5% were infected with Mansonella ozzardi. This finding was determined from a single 20-μL sample of finger prick blood from each person. Among children, < 2% had a detectable microfilaremia. In persons > 15 years of age, the prevalence of infection for males and females was 23% and 21%, respectively. In general, the microfilaremias were low and 70% of positive persons had < 10 microfilariae per 20 μL of blood; only 5% had > 50 microfilariae. This study shows that persons living near mangrove marshes that are breeding sites for Culicoides furens and C. barbosai biting midges, which are recognized vectors of M. ozzardi in Haiti, are consequently more frequently infected than those living in downtown area of Corail or inland., (© The American Society of Tropical Medicine and Hygiene.)

During August 2010-December 2012, we conducted a study of patients in Ghana who had Buruli ulcer, caused by Mycobacterium ulcerans, and found that 23% were co-infected with Mansonella perstans nematodes; 13% of controls also had M. perstans infection. M. perstans co-infection should be considered in the diagnosis and treatment of Buruli ulcer.

Mansonella (M.) perstans filariasis is widely found in Africa, including Gabon where Loa loa is also endemic. This study reports the total IgE titres according to different bioclinical forms of single or co-infection with L. loa and M. perstans in 138 patients and 20 healthy controls. The median parasite density was significantly higher in cases of loiasis. IgE titres were higher in patients with microscopic dual-infection and in the group of patients with occult loiasis plus M. perstans microfilaraemia (8425 [5292-20,679]KUI/L and 6304 [1045-10,326]KUI/L, respectively), compared to individuals with either microfilaraemic Loa loa (3368 [1414-7074]KUI/L) or Mansonella (4370 [1478-7334]KUI/L) single infections (p<0.01). IgE levels were positively correlated with M. perstans microfilaraemia (rho=0.27; p<0.01). Compared to single infections, dual M. perstans-L. loa infection induces very high total IgE titres. Studies correlating IgE titres and clinical symptoms are needed to confirm the involvement of this immunoglobulin in the pathological processes during filariasis., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A case of co-infection with Plasmodium vivax and Mansonella ozzardi was detected in a blood sample from a person who had shown symptoms of malaria and lived in a city that was close to the Argentina/Bolivia border. The case was detected during a random revision of thick and thin smears from patients diagnosed with malaria from various towns and cities located in north-western Argentina between 1983 and 2001. Trophozoites of P. vivax were observed in the thin blood smear along with M. ozzardi microfilaria (larval form), which presented a long, slender, pointed anucleate tail and the absence of the sheath. This last characteristic is shared with Mansonella perstans, Mansonella streptocerca and Onchocerca volvulus. More rigorously controlled studies to detect other co-infection cases in the area as well as the possibility of importation from Bolivia into Argentina are currently ongoing. The relationship between the malaria parasite and microfilaria, the potential effect of malaria treatment on the development of M. ozzardi, and the possible impact of this microfilaria on the immunity of a person against P. vivax are all still unknown. This contribution constitutes a point of focus for future studies involving the interaction between the parasites and the potential risk that humans are exposed to.

DNA sequence comparisons are useful for characterizing proposed new parasite species or strains. Microfilariae with an atypical arrangement of nuclei behind the cephalic space have been recently described in human blood samples from the Amazon region of Peru. Three blood specimens containing atypical microfilariae were genetically characterized using three DNA markers (5S ribosomal DNA, 12S ribosomal DNA, and cytochrome oxidase I). All atypical microfilariae were clustered into the Mansonella group and indistinguishable from M. ozzardi based on these DNA markers.

Mansonella ozzardi is a tissue-dwelling parasitic nematode, the causative agent of mansonelliasis in almost all Latin American countries. It has been described along the Argentine Yungas region. The microscopic diagnosis can yield false-negative test results at low microfilaremia levels. The aim of this study was to optimize the molecular diagnostic technique and compare it with the Knott's method and standard blood smear procedures (thin blood films and thick smears) in 92 blood samples of individuals from an endemic area. The PCR technique followed by the sequencing of the amplified product yielded 100 % sensitivity compared to the Knott's test, which is considered a reference method. Seven more cases of this parasitosis could only be identified with the molecular technique.

Introduction: The last few years has seen an increase in the number of immigrants and travellers from endemic areas where filariasis are mainly caused by Loa loa (L. loa), Mansonella perstans (M. perstans) and Wuchereria bancrofti (W. bancrofti) species. These demographic changes has led to the need for better filariae species-specific molecular diagnostic tests to solve problems, as alternatives to the more time consuming classic parasitology methods. Thus, the objective of the present work was the implementation of optimised molecular protocols (nested-PCR and ITS1-RFLP) developed in our laboratory, for the differential diagnosis of filarial parasites. The results obtained were compared with those obtained using the conventional parasitological methods., Material and Methods: A total of 523 samples (517 peripheral blood, 5 adult worms and one vitreous body) were sent to Parasitology Department of the National Microbiology Centre, Carlos II Research Institute (ISCIII), from 47 Health Centres in the Autonomous Regions of Spain, from 2006 to 2009. The samples were studied by the Knott technique, nested-PCR and ITS1-RFLP., Results: The molecular techniques applied on blood samples showed to be more sensitive that Knott's concentration technique in the diagnosis of both L. loa (n=12 versus n=4) and M. perstans (n=57 versus n=25) infections., Conclusions: The nested-PCR and ITS1-RFLP are potential diagnostic tools for daily routine laboratory species-specific and sensitive detection of L. loa and M. perstans filarial species in immigrant population and travellers from endemic areas where these filarial species are co-endemic. Knott's concentration technique was less sensitive than molecular methods and should be carried out as a complementary diagnostic assay., (Copyright © 2010 Elsevier España, S.L. All rights reserved.)

Mansonella perstans is a vector-borne human filarial nematode, transmitted by tiny blood-sucking flies (biting midges). It is widespread in many parts of Sub-Saharan Africa and also occurs in parts of Central and South America. Despite the commonness of this parasite very few studies have been carried out on its epidemiology and on the morbidity resulting from it, and only few thorough drug trials have been conducted to look for effective and suitable drugs and drug regimens for treatment and control. Here, we review currently available knowledge on M. perstans infections in Africa, including documented aspects of biology, vectors, transmission, diagnosis, epidemiology, morbidity and treatment. It is concluded that there is an urgent need for more research on this widespread but greatly neglected infection in order to properly assess its public health significance and as a background for identifying and recommending optimal means and strategies for treatment and control., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background & Objectives: The study was aimed at elucidating the prevalence and intensity of Mansonella perstans microfilaraemia in the Emohua Local Government Area, Nigeria, and ascertaining the abundance, circadian, and the annual biting patterns of the Culicoides vector., Methods: Thick smear of 50 µl finger-prick blood stained with Giemsa was examined microscopically in a cross-sectional study. Vector landing collection on human bait was employed in a longitudinal study of the vector biting patterns, carried out between July 2005 and August 2006., Results: Of 1486 individuals examined, 11.2% of both males and females were positive for M. perstans microfilaraemia. Microfilaraemia appeared early in life. The overall geometric mean intensity among those with positive microfilaraemia was 117 mf/ml (121 mf/ml for males and 113 mf/ml for females). The differences in geometric mean intensity between different age groups were statistically significant (one-way analysis of variance; p <0.05), being highest in the oldest age group (266 mf/ml). A total of 1183 female Culicoides sp were caught from September 2005 to August 2006. The abundance of Culicoides sp was seasonal. The circadian biting activity had a broad peak between 0700 and 1200 hrs. The monthly biting rates ranged from zero bite per person per month in January 2006 to 1151 bites per person per month in June 2006. The annual biting rate was 7382 bites per person per year., Conclusion: Majority of those with positive microfilaraemia were poor socioeconomically, underscoring the need for health education and application of effective control measures against Culicoides biting midges in Emohua.

The ribosomal deoxyribonucleic acid (DNA) internal transcribed spacer region (ITS1) of two filarial nematodes, Loa loa and Mansonella perstans, was amplified and further sequenced to develop an species-specific polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) protocol for the differentiation of both species from Wuchereria bancrofti, three filarial nematodes with blood circulating microfilariae. The ITS1-PCR product digested with the restriction endonuclease Ase I generated an specific diagnostic pattern for each of the three species. Moreover, three new specific nested-PCRs, targeting the ITS1 region, for differential detection of L. loa, M. perstans and W. bancrofti were developed and used when the ITS1-PCR products were insufficient for the Ase I enzymatic digestion. These filarial species-specific molecular protocols were evaluated in forty blood samples from African adult immigrants attending in the Hospital Insular of Gran Canaria, Canarias, Spain., (Copyright © 2010 Elsevier Inc. All rights reserved.)

We report the occurrence of serious reactions after treatment with oral ivermectin in two patients with Mansonella ozzardi infections. Both had systemic and respiratory symptoms and recovered without sequelae. Follow-up revealed clearance of microfilaremia in both cases, with relapse in one of them. These reactions are well described in the treatment of other filarial infections, but have not yet been reported in the treatment of M. ozzardi. We are now reporting the first such known reactions with this helminthiasis.

The Mansonella perstans microfilarial (mf) periodicity in peripheral blood was analysed in a group of 32 healthy individuals from an endemic community in Uganda. The majority of individuals had maximum mf intensity during the first and minimum during the last 12 h of the day. Mean mf ratios (i.e. time-specific counts in relation to mean count for the individual) indicated a weak but significant diurnal periodicity with peak intensity around 0800 h. Trigonometric analysis of the ratios, assuming a harmonic wave pattern of periodicity, gave a periodicity index of 11.1 and a peak time of 0645 h. The higher mf intensities in the early morning appeared to coincide with the preferred biting hour of the vectors. The observed weak pattern of mf periodicity indicates that the sampling time of blood specimens for diagnosis will have only minor effect on diagnostic sensitivity.

Purpose: To evaluate eye manifestations in mansonelliasis patients from Coari, AM, rural area on the middle Amazonas River., Methods: Cross-sectional study consisted of evaluation of 543 subjects from Coari rural area on Solimões River right margin. All subjects were submitted to blood test for microfilaria and the subjects who had a positive test also were submitted to skin biopsies and ophthalmologic examination. Histopathology and PCR research for microfilaria were done on eye biopsies of suspect lesions., Results: Mansonella ozzardi was found in peripheral blood of 103 (18.9%) subjects. Ninety-five mansonelliasis patients were examined. Punctate keratitis was observed in 12 of them, nummular keratitis in one subject and sclerosing keratitis in another one. Skin biopsies were negative in all subjects. Conjunctival and limbal biopsies were done in five mansonelliasis patients and corneal biopsy in another three patients. Conjunctival and limbal biopsies of two patients and corneal biopsy of one patient showed no microfilaria or alterations due to its presence on histopathology. PCR showed no evidence of microfilaria in the other biopsies., Conclusion: Association between Mansonella ozzardi infection and corneal lesions with no evident etiology was observed in this study, but the lack of conclusive findings on histopathology and PCR make us doubt the corneal involvement in mansonelliasis. Large studies of high mansonelliasis prevalence populations and extensive employment of microfilaria identification tests in ocular tissue are needed to evaluate the microfilaria corneal pathogenicity.

Filarial parasites infect an estimated 140 million people worldwide. Wuchereria bancrofti, Onchocerca volvulus, Loa loa and Mansonella perstans are responsible for most filarial infections in sub-Saharan Africa. We describe the prevalence and the clinical characteristics of filariasis in symptomatic patients in Goundi Sanitary district:167 patients were enrolled (99 men, 68 women). M. perstans microfilariae were isolated in peripheral blood in 164 cases, while Loa loa and Wuchereria bancrofti filariasis were diagnosed in only six and three cases, respectively. The most frequent filariasis observed in our study were due to M. perstans and L. loa, while the few cases of W. bancrofti filariasis seem to have been acquired abroad. No cases of O. volvulus were observed. Microfilarial burden was not related to symptoms, but a correlation between eosinophilia and pruritus was evident. No relationship was observed between eosinophils and symptoms. The prevalence observed in symptomatic patients could reflect the real prevalence of filariasis.

Mansonella perstans filariasis is widely present in Africa and equatorial America and its pathogenicity has been recently reconsidered. Effective treatment is lacking and there is no consensus on optimal therapeutic approach. We present the results of a new combination treatment against M. perstans filariasis. Two cases of M. perstans filariasis were treated with the combination of diethylcarbamazine (DEC) and thiabendazole. The treatment was able to significantly reduce microfilaria burden in a case and to achieve complete clearance of blood microfilariae in another case.

Mansonella perstans filariasis is widely present in Africa and equatorial America and its pathogenicity has been recently reconsidered. Although M. perstans infection has been considered a minor filariasis, remaining asymptomatic in most of infected subjects, more recent studies have shown that M. perstans is capable of inducing a variety of clinical features, including angioedemas, swellings like the "Calabar swellings" of loiasis, pruritus, fever, headache, pain in bursae and/or joint synovia, or in serous cavities. It is likely that some of the pathological changes observed are induced by the immune response to the infection. Eosinophilia is present in many cases of infection. Moreover M. perstans filariasis is difficult to be treated. Effective treatment is lacking and there is no consensus on optimal therapeutic approach. The most commonly used drug is diethylcarbamazine (DEC) that is however often ineffective. Although other drugs have been tried (e.g. praziquantel, ivermectin), none has proven to be reliably and rapidly effective. Mebendazole seemed more active than DEC in eliminating the infection, with a comparable rate of overall responses. Thiabendazole evidenced a small, but significant activity against the infection. Combination treatments (DEC plus mebendazole) resulted in a significantly higher activity compared with the single drugs.

Endosymbiotic Wolbachia bacteria from different filarial species, including major pathogens of humans such as Wuchereria bancrofti, Brugia malayi and Onchocerca volvulus, seem to play an important role in the development, viability and fertility of these worms. Wolbachia trigger inflammatory host responses as well as adverse reactions against standard treatment regimens and are therefore under investigation as novel treatment targets. We investigated whether Wolbachia are also endosymbiotic in Loa loa and Mansonella perstans. In both male and female adult L. loa, we found no evidence of bacteria by light or transmission electron microscopy. Furthermore, Wolbachia-specific PCR was negative in both L. loa and M. perstans microfilariae. The absence of Wolbachia in both filarial species therefore discourages the use of antibiotics as an adjunct or alternative approach to current treatment concepts for both loiasis and mansonelliasis perstans.

Mansonella perstans filariasis is widely distributed across the center of Africa and equatorial America. We describe a case of post-transfusional M. perstans microfilariasis in a young child, affected with severe Plasmodium falciparum malaria, admitted in Goundi Hospital in South of Chad. A decrease of M. perstans microfilariasis in the patient's blood was observed, with no subsequent development of either clinical symptoms or eosinophilia. We suggest that, in endemic areas, transfused M. perstans microfilariae may be cleared from the blood over relatively short periods of time. It is likely that only adult worms are responsible for symptoms and eosinophilia, whereas microfilariae in the bloodstream are unable to give clinical manifestations.

The prevalence and intensity of Loa loa and Mansonella perstans were studied in three villages of the Ijebu north area in Ogun State, western Nigeria. Blood samples were collected by finger-pricking from 373 (181 males, 192 females) subjects with an age range of 4 to 55 years. The blood samples were examined microscopically for the presence of microfilariae (mf). L. loa and M. perstans were present in the blood samples in 39 (10.5%) and 12 (3.2%) of the subjects, respectively. Neither of the infections were found to be sex-dependent. The geometric mean of the L. loa intensity was 1.8 mf per 50 microl of blood, while that of M. perstans was 1.5 mf per 50 microl. The prevalence of mixed infections of both L. loa and M. perstans was 1.0%.

Mansonella ozzardi, a relatively nonpathogenic filarial parasite of man in Latin America, is transmitted by either ceratopogonid midges or simuliid blackflies. In the only known focus of the disease in north-western Argentina the vectors have never been incriminated. This study investigated the potential vectors of M. ozzardi in this area. The only anthropophilic species of these Diptera families biting man at the time of the investigation were Simulium exiguum, S. dinellii, Culicoides lahillei and C. paraensis. Using experimentally infected flies S. exiguum and both species of Culicoides allowed full development of microfilariae to the infective stage, with C. lahillei being a more competent host than S. exiguum. Based on these data, biting rates and natural infectivity rates it is probable that at the begininning of the wet season C. lahillei is the main vector of M. ozzardi and both C. paraensis and S. exiguum secondary vectors. Additionally, it was found that a single dose of ivermectin was ineffectual in eradicating M. ozzardi from infected individuals in this area.

The internal transcribed spacer region (ITS1, 5.8S gene and ITS2) of the two filarial nematodes Onchocerca volvulus and Mansonella ozzardi was sequenced, and two species-specific primers designed in the ITS2 to develop a PCR-based method for their specific detection and differentiation. When used with a universal reverse primer, the two species-specific primers gave amplification products of different size, which were readily separated in an agarose gel. The PCR was tested on skin biopsies from 51 people from three localities in Brazil where M. ozzardi is present, and results have been compared with those of parasitological examination of blood. The species-specific PCR gave a higher percentage of detection of infection by M. ozzardi than the parasitological examination of blood. No infection with O. volvulus was detected by PCR. This PCR-based assay may assist in determining the nature of infection in areas where both filarial species exist in sympatry.