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Background: Scrub typhus is a mite-borne infectious disease caused by Orientia tsutsugamushi. Few follow-up studies have assessed antibody titers using serologic tests from various commercial laboratories and the Korea Centers for Disease Control and Prevention (KCDC).Methods: A prospective study to assess the antibody titers in patients with scrub typhus and seroprevalence in individuals undergoing health checkups was conducted using results of immunofluorescence antibody assays (IFAs) and serologic tests, used by the KCDC and commercial laboratories, respectively. The following tests were performed simultaneously: (i) indirect IFA used by the KCDC to detect immunoglobulin (Ig) M and IgG, (ii) IFA used by a commercial laboratory to detect total Ig, and (iii) antibody tests using two commercially available kits.Results: When the IgM and IgG cutoff values (≥1:16 and ≥1:256, respectively) used in the IFA and the total IgG cutoff values (≥1:40) were used in prospective follow-up investigations, the antibody positivity rates of 102 patients with scrub typhus were 44.1, 35.3, and 57.6%, respectively, within 5 days of symptom onset. Among 91 individuals who recovered from scrub typhus, the follow-up IgM, IgG, and total Ig positivity rates for 13 years were 37.4% (34/91), 22.0% (20/91), and 76.9% (70/91), respectively. Among 216 individuals undergoing health checkups, the seroprevalence of IgM was 4.2% (9/216); no seroprevalence of IgG was observed.Conclusions: IFAs used by the KCDC and the commercial laboratory and rapid commercial kits could not distinguish between patients who had recovered from scrub typhus and those who are currently infected with O. tsutsugamushi. In South Korea and other countries, where low antibody cutoff values are used, upward adjustments of cutoff values may be necessary. [ABSTRACT FROM AUTHOR]

Background: Anaplasmosis is an emerging acute febrile disease that is caused by a bite of an Anaplasma phagocytophilum-infected hard tick. As for healthy patients, reports on asymptomatic anaplasmosis resulting from such tick bites are rare.Case Presentation: A 55-year-old female patient visited the hospital with a tick bite in the right infraclavicular region. The tick was suspected to have been on the patient for more than 10 days. PCR and an indirect immunofluorescence assay (IFA) were performed to identify tick-borne infectious diseases. The blood sample collected at admission yielded a positive result in nested PCR targeting Ehrlichia- or Anaplasma-specific genes groEL and ankA. Subsequent sequencing confirmed the presence of A. phagocytophilum, and seroconversion was confirmed by the IFA involving an A. phagocytophilum antigen slide. PCR detected no Rickettsia-specific genes [outer membrane protein A (ompA) or surface cell antigen 1 (sca1)], but seroconversion of spotted fever group (SFG) rickettsiosis was confirmed by an IFA.Conclusions: This study genetically and serologically confirmed an asymptomatic A. phagocytophilum infection. Although SFG rickettsiosis was not detected genetically, it was detected serologically. These findings indicate the possibility of an asymptomatic coinfection: anaplasmosis plus SFG rickettsiosis. It is, therefore, crucial for clinicians to be aware of potential asymptomatic anaplasmosis following a tick bite. [ABSTRACT FROM AUTHOR]

Background: Tick-borne lymphadenopathy (TIBOLA) is an infectious disease, mainly caused by species from the spotted fever group rickettsiae and is characterized by enlarged lymph nodes following a tick bite. Among cases of TIBOLA, a case of scalp eschar and neck lymphadenopathy after tick bite (SENLAT) is diagnosed when an eschar is present on the scalp, accompanied by peripheral lymphadenopathy (LAP). Only a few cases of SENLAT caused by Bartonella henselae have been reported.Case Presentation: A 58-year-old male sought medical advice while suffering from high fever and diarrhea. Three weeks before the visit, he had been hunting a water deer, and upon bringing the deer home discovered a tick on his scalp area. Symptoms occurred one week after hunting, and a lump was palpated on the right neck area 6 days after the onset of symptoms. Physical examination upon presentation confirmed an eschar-like lesion on the right scalp area, and cervical palpation revealed that the lymph nodes on the right side were non-painful and enlarged at 2.5 × 1.5 cm. Fine needle aspiration of the enlarged lymph nodes was performed, and results of nested PCR for the Bartonella internal transcribed spacer (ITS) confirmed B. henselae as the causative agent.Conclusion: With an isolated case of SENLAT and a confirmation of B. henselae in Korea, it is pertinent to raise awareness to physicians in other Asian countries that B. henselae could be a causative agent for SENLAT. [ABSTRACT FROM AUTHOR]

Background Scrub typhus is a mite-borne infectious disease caused by Orientia tsutsugamushi. There have been few follow-up studies assessing antibody titers using serologic tests from various commercial labs. Methods A prospective investigation to assess antibody titers of scrub typhus patients and seroprevalence for health checkup individuals were evaluated. The antibody titers of former patients diagnosed with scrub typhus at least 1 year and a maximum of 13 years were also investigated. The following tests were performed simultaneously: (i) immunofluorescence antibody assays (IFAs) that detect immunoglobulin(Ig) M and IgG, (ii) IFA that detects total Ig by a commercial lab, (iii) antibody tests using two commercially available kits. Results In prospective analyses with cutoff values set to ≥1:16 for IgM, ≥1:256 for IgG based on the KCDC's criteria, and ≥1:40 for total Ig. The antibody positive rates of 102 confirmed scrub typhus patients were 44%, 35.3%, and 57.6%, respectively, in the first week after symptom onset. Among 91 former patients recovered, the follow-up IgM, IgG, and total Ig positivity rates were 38.5% (35/91), 22% (20/91), and 76.9% (70/91), respectively. In overall cohort of 216 health checkup subjects, 4.2% (9/216) IgM and 0% (0/216) IgG seroprevalence was observed. Conclusion The IFA from KCDC and commercial lab, and rapid commercial kits cannot differentiate between former patients recovered from scrub typhus and current scrub typhus. In Korea and other countries where low antibody cut-off titer values have been used as criteria for diagnosing and reporting scrub typhus, upward adjustments of cut-off values may be necessary. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Scrub typhus, anaplasmosis, and leptospirosis are well-known diseases that are considered common, widespread rodent-borne infectious diseases Methods This study investigated the prevalence of Orientia tsutsugamushi , Anaplasma phagocytophilum , and Leptospira interrogans in wild rodents through molecular detection using organ samples and through serological assay using blood samples of mice collected from two distinct sites in Gwangju Metropolitan City, Republic of Korea (ROK). Results A total of 47 wild rodents, identified as Apodemus agrarius (A. agrarius), were captured from June to August 2016. The seroprevalence of antibodies against bacterial pathogens in A. agrarius sera was analyzed; 17.4% (8/46) were identified as O. tsutsugamushi through indirect immunofluorescence assay and 2.2% (1/46) were identified as Leptospira species through passive hemagglutination assay. Using polymerase chain reaction, the spleen, kidney and blood samples were investigated for the presence of O. tsutsugamushi, A. phagocytophilum , and L. interrogans. Out of the 47 A. agrarius , 19.1% (9/47) were positive for A. phagocytophilum and 6.4% (3/47) were positive for L. interrogans , while none were positive for O. tsutsugamushi. Four out of 46 (8.7%) blood samples, six out of 45 (13.3%) spleen samples, and one out of 47 (2.1%) kidney samples were positive for A. phagocytophilum. Three out of 47 (6.4%) kidney samples were positive for L. interrogans. The sequencing results of PCR positive samples demonstrated >99% similarity with A. phagocytophilum and L. interrogans sequences Conclusion A. phagocytophilum was mostly detected in the spleen, whereas L. interrogans was mostly detected in the kidneys. Notably, A. phagocytophilum and L. interrogans were detected in A. agrarius living in close proximity to humans in the metropolitan suburbans. The results of this study indicate that rodent-borne bacteria may be present in wild rodents in the metropolitan suburban areas of ROK Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

• The numbers of O. tsutsugamushi DNA copies in surviving and non-surviving patients were significantly different (p <0.001). • Our finding demonstrates the relationship between O. tsutsugamushi DNA copy load and fatality in patients with scrub typhus. • Our study demonstrated that the disease severity was associated with the genotypes and bacterial load in patients infected with O. tsutsugamushi. Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi and is endemic to many parts of the Asia-Pacific region. We investigated whether the genotype of O. tsutsugamushi or the DNA load would be a useful marker of disease severity in scrub typhus patients. We evaluated the clinical features, genotypes and bacterial DNA load in the blood of 118 patients, including 114 surviving and 4 non-surviving patients, admitted at Chosun University Hospital. Four patients infected with the Pajoo, Yonchon, Youngworl and Boryong genotypes died. In the 114 survivors, 100 Boryong and 2 Taguchi genotypes were identified. The genotypes involved showed significant differences between the surviving and non-surviving patients (p <0.001). The median number of O. tsutsugamushi DNA copies was 78 copies /μL (range 3,960) in surviving patients, whereas 83,800 copies/μL (range 244,600) in the non-surviving patients. We found that the genotype and DNA load in the patient's blood are useful markers of disease severity in scrub typhus. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus is an acute disease, characterized by symptoms of fever, which occurs due to infection by Orientia tsutsugamushi. In most cases, patients recover from the disease with appropriate treatment, but serious and fatal complications may occur. The present study examined laboratory findings and tumor necrosis factor-alpha (TNF-α) levels of scrub typhus patients to identify the prognostic predictors of disease severity.Method: Patients whose scrub typhus diagnosis was confirmed by elevated indirect fluorescent antibody (IFA) levels and positive polymerase chain reaction (PCR) results were classified according to disease severity into one of three groups; i.e., deceased (n = 7), severe (n = 15), and mild (n = 15) retrospectively registered. Additionally, the usefulness of modified Acute Physiology and Chronic Health Evaluation II (APACHE II) score, C-reactive protein (CRP) level, white blood cell (WBC) count, and TNF-α level as prognostic predictors were examined.Result: The mean TNF-α levels of the deceased, severe, and mild groups were 53.5 (range: 7.8-147.8), 26.0 (1.7-64.4), and 8.8 pg/mL (4.6-16.0), respectively. The results of Kruskal-Wallis tests showed statistically significant differences between the deceased and severe groups versus the mild group (p = 0.005). CRP level and Modified APACHE II score also differed significantly among the groups (p = 0.046 and 0.007, respectively); however, WBC count did not (p = 0.196).Conclusion: An elevated serum TNF-α level in patients with scrub typhus could predict a severe condition or death and may be useful in predicting patient prognosis. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi, a gram-negative intracellular bacterium. Myocarditis and rhabdomyolysis are rare complications of scrub typhus.Case Presentation: We report a case of scrub typhus, which was simultaneously complicated with myocarditis and rhabdomyolysis. A 54-year-old woman presented to our hospital with myalgia in the upper and lower limbs, oedema and a fever of 7 days' duration. We confirmed the diagnosis of scrub typhus complicated with myocarditis by pericardial fluid analysis and cardiac magnetic resonance imaging results. The pericardial fluid showed characteristics of an exudate, an elevated immunofluorescence assay (IFA) IgG titer of 1:2048 and a positive 16S rRNA qPCR result. We also diagnosed rhabdomyolysis by the patient's presenting symptoms, elevated muscle enzyme levels and bone scan results.Conclusion: We report for the first time a case of scrub typhus complicated with both myocarditis and rhabdomyolysis, the causative agent of which was the Boryong genotype of O. tsutsugamushi. [ABSTRACT FROM AUTHOR]