Identification of potential hosts and vectors of scrub typhus and tick-borne spotted fever group rickettsiae in eastern Taiwan

Kuo, Chi‐Chien; Huang, Chien‐Ling; Wang, Hsi Chieh

doi:10.1111/j.1365-2915.2010.00941.x

Cited by 48 publications

(54 citation statements)

References 32 publications

(32 reference statements)

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“…These findings are comparable to the results of our previous study on seroprevalence for R. conorii in rodents in eastern Taiwan (Hualien, 91.9%), which was conducted using the same methods (Kuo et al 2011). Such a high seroprevalence may not be surprising in light of the high rate of infection (60.5%) among small mammals, which indicates that rickettsiae infections circulate at high numbers in fields and suggests a high human risk for Rickettsia infections, although some species may not be human pathogens.…”

Section: Discussionsupporting

confidence: 81%

“…Briefly, each rodent serum sample was diluted 1:40 in phosphate-buffered saline (PBS), applied to slides coated with R. conorii, R. rickettsii, or R. typhi antigens (Focus Technologies, Inc., Cypress, CA), and mixed by pipetting with fluorescein isothiocyanate-goat anti-mouse immunoglobulin G (IgG) + A + M (H + L; Zymed Laboratories, Inc., San Francisco, CA) diluted 1:40 in PBS. PBS was used as a negative control; positive controls were not included in this study because our parallel serological studies (Kuo et al 2011(Kuo et al , 2012 confirmed the validity of the test, and excluding positive controls would allow an assay of more individuals for each antigen slide. We chose 1:40 as the cutoff titer because this is the same criterion used for confirmation of human cases of rickettsial diseases (mainly scrub typhus) in Taiwan by the Taiwan Centers for Disease Control.…”

Section: Immunofluorescent Antibody Assaymentioning

confidence: 99%

“…We followed the method described by Kuo et al (2011Kuo et al ( , 2012 for the assessment of seroprevalence of Rickettsia spp. Briefly, each rodent serum sample was diluted 1:40 in phosphate-buffered saline (PBS), applied to slides coated with R. conorii, R. rickettsii, or R. typhi antigens (Focus Technologies, Inc., Cypress, CA), and mixed by pipetting with fluorescein isothiocyanate-goat anti-mouse immunoglobulin G (IgG) + A + M (H + L; Zymed Laboratories, Inc., San Francisco, CA) diluted 1:40 in PBS.…”

Section: Immunofluorescent Antibody Assaymentioning

confidence: 99%

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High Prevalence ofRickettsiaspp. Infections in Small Mammals in Taiwan

Kuo

Shu

et al. 2015

Vector-Borne and Zoonotic Diseases

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Surveillance for Rickettsia spp. is urgently needed due to the recent emergence of many novel rickettsioses around the globe, but previous studies in Taiwan have been limited to small areas and no investigation of infections in vertebrate hosts has ever been attempted. We surveyed rickettsial infections systematically in small-mammal hosts trapped between 2006 and 2010 throughout Taiwan. Fragments of ompB and gltA genes in the liver, spleen, and kidney of mammals were targeted by nested polymerase chain reaction. We trapped 1375 individuals of 10 species, among which Rattus losea was the most common (54.6%), followed by Suncus murinus (20.6%) and Mus caroli (10.6%). The overall rate of Rickettsia infections in the liver, spleen, or kidney of 309 assayed small mammals was 60.5%, with a rate of infection ‡ 50% for each mammal species. DNA nucleotide sequences of 184 successfully sequenced genes were most similar to nine Rickettsia species: Rickettsia conorii, R. felis, R. japonica, R. raoultii, R. rickettsii, Rickettsia sp. IG-1, Rickettsia sp. TwKM01, Rickettsia sp. TwKM02, and R. typhi. Our results suggest that several novel Rickettsia spp. are common and widespread across various habitats throughout Taiwan and suggest the need for further study of emerging rickettsioses in Taiwan.

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Section: Discussionsupporting

confidence: 81%

Section: Immunofluorescent Antibody Assaymentioning

confidence: 99%

Section: Immunofluorescent Antibody Assaymentioning

confidence: 99%

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High Prevalence ofRickettsiaspp. Infections in Small Mammals in Taiwan

Kuo

Shu

et al. 2015

Vector-Borne and Zoonotic Diseases

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“…However, there is local variation of major vectors such as L . imphalum in eastern Taiwan [59], L . chiangraiensis and L .…”

Section: Resultsmentioning

confidence: 99%

Diversification of Orientia tsutsugamushi genotypes by intragenic recombination and their potential expansion in endemic areas

Kim

Min

et al. 2017

PLoS Negl Trop Dis

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BackgroundScrub typhus is a mite-borne febrile disease caused by O. tsutsugamushi infection. Recently, emergence of scrub typhus has attracted considerable attention in several endemic countries in Asia and the western Pacific. In addition, the antigenic diversity of the intracellular pathogen has been a serious obstacle for developing effective diagnostics and vaccine.Methodology/Principal findingsTo understand the evolutionary pathway of genotypic diversification of O. tsutsugamushi and the environmental factors associated with the epidemiological features of scrub typhus, we analyzed sequence data, including spatiotemporal information, of the tsa56 gene encoding a major outer membrane protein responsible for antigenic variation. A total of 324 tsa56 sequences covering more than 85% of its open reading frame were analyzed and classified into 17 genotypes based on phylogenetic relationship. Extensive sequence analysis of tsa56 genes using diverse informatics tools revealed multiple intragenic recombination events, as well as a substantially higher mutation rate than other house-keeping genes. This suggests that genetic diversification occurred via frequent point mutations and subsequent genetic recombination. Interestingly, more diverse bacterial genotypes and dominant vector species prevail in Taiwan compared to other endemic regions. Furthermore, the co-presence of identical and sub-identical clones of tsa56 gene in geographically distant areas implies potential spread of O. tsutsugamushi genotypes.Conclusions/SignificanceFluctuation and diversification of vector species harboring O. tsutsugamushi in local endemic areas may facilitate genetic recombination among diverse genotypes. Therefore, careful monitoring of dominant vector species, as well as the prevalence of O. tsutsugamushi genotypes may be advisable to enable proper anticipation of epidemiological changes of scrub typhus.

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“…Mice belong to the wildlife host range of O. tsutsugamushi [7], [8]. A number of different genetic backgrounds and inoculation routes have been used to study O. tsutsugamushi infection in mice, including the intraperitoneal (i.p.…”

Section: Introductionmentioning

confidence: 99%

Dissemination of Orientia tsutsugamushi and Inflammatory Responses in a Murine Model of Scrub Typhus

et al. 2014

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Central aspects in the pathogenesis of scrub typhus, an infection caused by Orientia (O.) tsutsugamushi, have remained obscure. Its organ and cellular tropism are poorly understood.The purpose of this study was to analyze the kinetics of bacterial dissemination and associated inflammatory responses in infected tissues in an experimental scrub typhus mouse model, following infection with the human pathogenic strain Karp. We provide a thorough analysis of O. tsutsugamushi infection in inbred Balb/c mice using footpad inoculation, which is close to the natural way of infection. By a novel, highly sensitive qPCR targeting the multi copy traD genes, we quantitatively monitored the spread of O. tsutsugamushi Karp from the skin inoculation site via the regional lymph node to the internal target organs. The highest bacterial loads were measured in the lung. Using confocal imaging, we also detected O. tsutsugamushi at the single cell level in the lung and found a predominant macrophage rather than endothelial localization. Immunohistochemical analysis of infiltrates in lung and brain revealed differently composed lesions with specific localizations: iNOS-expressing macrophages were frequent in infiltrative parenchymal noduli, but uncommon in perivascular lesions within these organs. Quantitative analysis of the macrophage response by immunohistochemistry in liver, heart, lung and brain demonstrated an early onset of macrophage activation in the liver. Serum levels of interferon (IFN)-γ were increased during the acute infection, and we showed that IFN-γ contributed to iNOS-dependent bacterial growth control.Our data show that upon inoculation to the skin, O. tsutsugamushi spreads systemically to a large number of organs and gives rise to organ-specific inflammation patterns. The findings suggest an essential role for the lung in the pathogenesis of scrub typhus. The model will allow detailed studies on host-pathogen interaction and provide further insight into the pathogenesis of O. tsutsugamushi infection.

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Identification of potential hosts and vectors of scrub typhus and tick-borne spotted fever group rickettsiae in eastern Taiwan

Cited by 48 publications

References 32 publications

High Prevalence ofRickettsiaspp. Infections in Small Mammals in Taiwan

High Prevalence ofRickettsiaspp. Infections in Small Mammals in Taiwan

Diversification of Orientia tsutsugamushi genotypes by intragenic recombination and their potential expansion in endemic areas

Dissemination of Orientia tsutsugamushi and Inflammatory Responses in a Murine Model of Scrub Typhus

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