Challenges in diagnosing scrub typhus among hospitalized patients with undifferentiated fever at a national tertiary hospital in northern Vietnam

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,...

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Bibliographic Details
Published in:PLoS neglected tropical diseases Vol. 13; no. 12; p. e0007928
Main Authors: Katoh, Shungo, Cuong, Ngo Chi, Hamaguchi, Sugihiro, Thuy, Pham Thanh, Cuong, Do Duy, Anh, Le Kim, Anh, Nguyen Thi Hien, Anh, Dang Duc, Sando, Eiichiro, Suzuki, Motoi, Fujita, Hiromi, Yasunami, Michio, Yoshihara, Keisuke, Yoshida, Lay-Myint, Paris, Daniel Henry, Ariyoshi, Koya
Format: Journal Article
Language:English
Published: United States Public Library of Science 01.12.2019
Public Library of Science (PLoS)
Subjects:
Adolescent
Adult
Aged
Aged, 80 and over
Biology and Life Sciences
Computer and Information Sciences
Diagnostic Tests, Routine - methods
Female
Fever - diagnosis
Fever - etiology
Humans
Male
Medicine and Health Sciences
Middle Aged
Molecular Diagnostic Techniques - methods
People and Places
Prospective Studies
Research and Analysis Methods
Scrub Typhus - diagnosis
Scrub Typhus - epidemiology
Scrub Typhus - pathology
Serologic Tests - methods
Tertiary Care Centers
Vietnam - epidemiology
Young Adult
Vietnam
ISSN:1935-2735, 1935-2727, 1935-2735
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Summary: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. 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). 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.
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The authors have declared that no competing interests exist.
ISSN:1935-2735
1935-2727
1935-2735
DOI:10.1371/journal.pntd.0007928