Scrub Typhus in Previously Unrecognized Areas of Endemicity in China

Zhang, Shouyin; Song, Hongbin; Liu, Yan; Li, Qun; Wang, Yong; Wu, Jing; Wan, Jianxin; GuoLan, Li; Chang-jun, YU; Li, Xiuyong; Yin, Wenwu; Xu, Zhihua; Liu, Bo; Zhang, Qian; Wan, Kanglin; Li, Guichang; Fu, Xin; Zhang, Jingshan; He, Jijun; Hai, Rong; Yu, Dongzheng; Walker, David H.; Xu, Jianguo; Yu, Xue‐Jie

doi:10.1128/jcm.01784-09

Cited by 70 publications

(65 citation statements)

References 4 publications

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“…It has been estimated that 1 billion people are at risk, and 1 million new cases arise annually in the Asian-Pacific region (23). This infectious disease has recently become an important public health issue due to regional outbreaks (16,18) and new emergence (6,28). Clinical presentations of scrub typhus, typically characterized by eschar, fever, rash, lymphadenopathy, and myalgia, can vary in severity from a mild and self-limiting flu-like syndrome to a life-threatening disease (13,25).…”

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confidence: 99%

Detection of Antibodies against Orientia tsutsugamushi Sca Proteins in Scrub Typhus Patients and Genetic Variation of sca Genes of Different Strains

Kim

Choi

et al. 2012

Clin Vaccine Immunol

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ABSTRACTScrub typhus, caused byOrientia tsutsugamushiinfection, is one of the main causes of acute febrile illness in the Asian-Pacific region. Although early diagnosis and immediate antibiotic treatment are critical for reducing disease severity and mortality, current diagnostic methods using serological and molecular approaches have some limitations in sensitivity and applicability in clinical laboratories. In this study, we identified and characterizedO. tsutsugamushisurface cell antigen (sca) family genes encoding autotransporter proteins in order to test them as novel diagnostic targets. We evaluated antibody responses against the Sca proteins in scrub typhus patient sera and examined the genetic diversity of these genes in different strains after PCR amplification. Specific antibody responses against ScaA and ScaC were observed in patients with high indirect immunofluorescence assay titers (≥1:640), whereas specific responses against ScaB and ScaE were relatively low. Genetic analysis using genomic DNAs revealed thescagenes to be quite variable among the different strains. In contrast toscaA,scaC, andscaD, which were detected in all of the tested strains,scaBandscaEwere amplified differentially from the different strains, suggesting a differential presence of the genes in the genomes. Among the members of the gene family, the sequence ofscaCis the most highly conserved between the different strains, and the size ofscaDis the most variable due to the presence of different numbers of internal repeat sequences. These results suggest that thescagenes ofO. tsutsugamushimay be valuable targets for use in combination with classical assay methods for scrub typhus diagnosis.

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confidence: 99%

Detection of Antibodies against Orientia tsutsugamushi Sca Proteins in Scrub Typhus Patients and Genetic Variation of sca Genes of Different Strains

Kim

Choi

et al. 2012

Clin Vaccine Immunol

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“…An estimated 1 billion people in this area are at risk from scrub typhus, with an estimated 1 million new cases occurring annually (36). The rapid increase in scrub typhus cases (17), coupled with new outbreaks within some areas of disease endemicity (38) in which the disease has not been seen previously, is becoming a public health issue. Even though scrub typhus is effectively treated with antibiotics such as doxycycline and chloramphenicol, reinfections are common because of the wide variety of antigenically distinct serotypes (15).…”

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confidence: 99%

An Autotransporter Protein from Orientia tsutsugamushi Mediates Adherence to Nonphagocytic Host Cells

Cho

Kim

et al. 2011

Infect Immun

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Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular pathogen whose mechanism of cellular adhesion and invasion is poorly characterized. Bioinformatic analyses of two O. tsutsugamushi genomes revealed the presence of a group of genes that encode autotransporter proteins. In this study, we identified 10 autotransporter gene products and categorized them into five groups of orthologs (ScaA to ScaE) based on their sequence similarities. Sequence homology was highest between members of ScaC group, suggesting the functional conservation of bacterium-host interactions. ScaC was actively expressed on the surface of O. tsutsugamushi and induced antibody responses in scrub typhus patients. Experiments using microbeads conjugated to recombinant ScaC or a surrogate Escherichia coli expression system showed that ScaC was sufficient to mediate attachment to, but not invasion of, nonphagocytic mammalian cells. In addition, preincubation of host cells with recombinant ScaC significantly inhibited their interaction with O. tsutsugamushi. Finally, fibronectin was identified as a potential receptor for ScaC by using yeast two-hybrid screening, and this was confirmed using a glutathione S-transferase (GST) pulldown assay. Taken together, these results demonstrate that ScaC is involved in the interaction of O. tsutsugamushi with mammalian host cells and suggest that ScaC may play a critical role in bacterial pathogenesis.

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“…6 an eschar is formed when an infected chigger bites the skin while feeding on human skin. It bites in warm, damp areas like axilla, groin.…”

Section: Discussionmentioning

confidence: 99%

Distribution of Eschar in Children With Scrub Typhus

Gane¹,

Natarajan²,

Hiremath³

2015

jemds

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Scrub typhus is caused by an intracellular bacterium, Orientia tsutsugamushi. It causes a disseminated vasculitic and perivascular inflammatory lesions. These lead to significant vascular leakage and end-organ injury. Eschar is the site of inoculation. It is painless and non-pruritic. It is a useful indicator of the disease. We studied the scrub typhus children with eschar to describe its distribution. MATERIAL AND METHODS: This is a retrospective study done in tertiary care hospital. Study was done with aim of studying the distribution of eschar. Patients included in study are: confirmed to have scrub typhus with a positive Scrub typhus IgM ELISA test and presence of eschar, Children less than 18 years. Data collected regarding clinical profile of cases and eschar distribution. RESULTS:Totally 52 cases with eschar were included in the study. Commonest site of eschar was axilla followed by groin. Other common sites of eschar included abdomen and chest. CONCLUSION: Detection of eschar helps clinically to distinguish scrub typhus from other febrile illness. Knowledge of common eschar sites would be useful for early clinical diagnosis of scrub typhus.

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Scrub Typhus in Previously Unrecognized Areas of Endemicity in China

Cited by 70 publications

References 4 publications

Detection of Antibodies against Orientia tsutsugamushi Sca Proteins in Scrub Typhus Patients and Genetic Variation of sca Genes of Different Strains

Detection of Antibodies against Orientia tsutsugamushi Sca Proteins in Scrub Typhus Patients and Genetic Variation of sca Genes of Different Strains

An Autotransporter Protein from Orientia tsutsugamushi Mediates Adherence to Nonphagocytic Host Cells

Distribution of Eschar in Children With Scrub Typhus

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