부산대학교 도서관

Background: Scrub typhus (ST) is a leading cause of non-malarial febrile illness in Southeast Asia, but evidence of its true disease burden is limited because of difficulties of making the clinical diagnosis and lack of adequate diagnostic tests. To describe the epidemiology and clinical characteristics of ST, we conducted an observational study using multiple diagnostic assays at a national tertiary hospital in Hanoi, Vietnam. Methodology/Principal findings: We enrolled 1,127 patients hospitalized with documented fever between June 2012 and May 2013. Overall, 33 (2.9%) patients were diagnosed with ST by PCR and/or screening of ELISA for immunoglobulin M (IgM) with confirmatory tests: 14 (42.4%) were confirmed by indirect immunoperoxidase assay (IIP), and 19 (57.6%) were by IIP and PCR. Living by farming, conjunctival injection, eschar, aspartate aminotransferase elevation, and alanine aminotransferase elevation were significantly associated with ST cases (adjusted odds ratios (aORs): 2.8, 3.07, 48.8, 3.51, and 4.13, respectively), and having a comorbidity and neutrophilia were significantly less common in ST cases (aORs: 0.29 and 0.27, respectively). The majority of the ST cases were not clinically diagnosed with rickettsiosis (72.7%). Dominant IIP reactions against a single antigen were identified in 15 ST cases, whereas indistinguishably high reactions against multiple antigens were seen in 11 ST cases. The most frequently observed dominant IIP reaction was against Karp antigen (eight cases) followed by Gilliam (four cases). The highest diagnostic accuracy of IgM ELISA in acute samples was 78%. In a phylogenetic analysis of the 56-kDa type-specific antigen gene, the majority (14 cases) were located in the Karp-related branch followed by the Gilliam-related (two cases), Kato-related (two cases), and TA763-related clades (one case). Conclusions/Significance: Both the clinical and laboratory diagnoses of ST remain challenging at a tertiary hospital. Implementation of both serological and nucleic acid amplification assays covering endemic O. tsutsugamushi strains is essential. Author summary: Acute fever without localized signs is a common presentation of communicable neglected tropical diseases (NTDs). Scrub typhus, a potentially severe chigger-borne intracellular bacterial infection, is also an important differential diagnosis of acute febrile NTDs, which is endemic particularly in Asia. In Vietnam, the proportion of scrub typhus cases among patients with acute fever is currently unknown even in a tertiary hospital, because both clinical and laboratory diagnoses of scrub typhus are challenging. In this study, we enrolled acute fever patients hospitalized in the department of infectious diseases at a national tertiary hospital in Hanoi through a year. Scrub typhus was diagnosed using serological and PCR assays in 2.9% of enrolled patients. We found that the characteristics of scrub typhus patients were generally non-specific and most cases were missed based on clinical diagnosis alone. We also found that currently available serological assays were sub-optimal in Vietnam by comparing multiple diagnostic assays. Since the diagnostic antigens were not originally from Vietnam, the serological findings may underrepresent the actual number of cases. The presented data underlines the importance of a preemptive treatment strategy for scrub typhus among acute fever patients and adaptation of diagnostic assays to cover endemic strains. [ABSTRACT FROM AUTHOR]