Prevalence and Phylogenetic Analysis of<i>Orientia tsutsugamushi</i>in Rodents and Mites from Central India

Bhate, Ruchi; Pansare, Nilesh; Chaudhari, S. P.; Barbuddhe, S. B.; Choudhary, V. K.; Kurkure, N. V.; Kolte, S. W.

doi:10.1089/vbz.2017.2159

Cited by 17 publications

(13 citation statements)

References 45 publications

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“…ticks removed from rodents tested positive for O. tsutsugamushi by PCR in Shandong Province, China [46]. Ornithonyssus bacoti (Macronyssidae) removed from rodents in Nagpur, India, tested positive by PCR (1 of 5 pools) [47] and in the review of rickettsial disease in China by Fan et al [26], Echinolaelaps echidninus and Laelaps turkestanicus also tested positive, but further details are not provided (Fig. 13).…”

Section: Resultsmentioning

confidence: 99%

“…The possibility of other vectors of scrub typhus should not be ignored, particularly in areas distant to the classical scrub typhus “triangle”, including the United Arab Emirates and Chile. Several reports of ticks testing positive for O. tsutsugamushi have been published [45, 46] and recently for a non-chigger mite, Ornithonyssus bacoti [47]. Orientia tsutsugamushi has been shown to multiply in inoculated ixodid ticks [171].…”

Section: Resultsmentioning

confidence: 99%

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Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

et al. 2019

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Scrub typhus, caused by Orientia tsutsugamushi, is an important and neglected vector-borne zoonotic disease with an expanding known distribution. The ecology of the disease is complex and poorly understood, impairing discussion of public health interventions. To highlight what we know and the themes of our ignorance, we conducted a systematic review of all studies investigating the pathogen in vectors and non-human hosts. A total of 276 articles in 7 languages were included, with 793 study sites across 30 countries. There was no time restriction for article inclusion, with the oldest published in 1924. Seventy-six potential vector species and 234 vertebrate host species were tested, accounting for over one million trombiculid mites (‘chiggers’) and 83,000 vertebrates. The proportion of O. tsutsugamushi positivity was recorded for different categories of laboratory test and host species. Vector and host collection sites were geocoded and mapped. Ecological data associated with these sites were summarised. A further 145 articles encompassing general themes of scrub typhus ecology were reviewed. These topics range from the life-cycle to transmission, habitats, seasonality and human risks. Important gaps in our understanding are highlighted together with possible tools to begin to unravel these. Many of the data reported are highly variable and inconsistent and minimum data reporting standards are proposed. With more recent reports of human Orientia sp. infection in the Middle East and South America and enormous advances in research technology over recent decades, this comprehensive review provides a detailed summary of work investigating this pathogen in vectors and non-human hosts and updates current understanding of the complex ecology of scrub typhus. A better understanding of scrub typhus ecology has important relevance to ongoing research into improving diagnostics, developing vaccines and identifying useful public health interventions to reduce the burden of the disease.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

et al. 2019

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“…Nonetheless, regardless of how the genetic diversity of Ots TSA arose, a better understanding of the contemporary quality and quantity of antigenic diversity of TSA in Ots is a prerequisite for designing specific serological diagnostic assays, and for developing more efficient vaccines. We therefore investigated the prevalence of TSA antigenic variants in Ots from India [ 19 , 20 ] and predicted the immunodominant CD4 TCEs that would be associated with significant HLA-DR binding affinity. In this context, we recognized the importance of analyzing the different TSA domains to find those immunogenic features and interactions which appear to be most conserved in most Indian individuals experiencing scrub typhus infections.…”

Section: Introductionmentioning

confidence: 99%

Complexity of type-specific 56 kDa antigen CD4 T-cell epitopes of Orientia tsutsugamushi strains causing scrub typhus in India

2018

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Orientia tsutsugamushi (Ots) is an obligate, intracellular, mite-transmitted human pathogen which causes scrub typhus. Understanding the diversity of Ots antigens is essential for designing specific diagnostic assays and efficient vaccines. The protective immunodominant type-specific 56 kDa antigen (TSA) of Ots varies locally and across its geographic distribution. TSA contains four hypervariable domains. We bioinformatically analyzed 345 partial sequences of TSA available from India, most of which contain only the three variable domains (VDI-III) and three spacer conserved domains (SVDI, SVDII/III, SVDIII). The total number (152) of antigenic types (amino acid variants) varied from 14–36 in the six domains of TSA that we studied. Notably, 55% (787/1435) of the predicted CD4 T-cell epitopes (TCEs) from all the six domains had high binding affinities (HBA) to at least one of the prevalent Indian human leukocyte antigen (HLA) alleles. A surprisingly high proportion (61%) of such TCEs were from spacer domains; indeed 100% of the CD4 TCEs in the SVDI were HBA. TSA sequences from India had more antigenic types (AT) than TSA from Korea. Overall, >90% of predicted CD4 TCEs from spacer domains were predicted to have HBA against one or more prevalent HLA types from Indian, Korean, Asia-Pacific region or global population data sets, while only <50% of CD4 TCEs in variable domains exhibited such HBA. The phylogenetically and immunologically important amino acids in the conserved spacer domains were identified. Our results suggest that the conserved spacer domains are predicted to be functionally more important than previously appreciated in immune responses to Ots infections. Changes occurring at the TCE level of TSA may contribute to the wide range of pathogenicity of Ots in humans and mouse models. CD4 T-cell functional experiments are needed to assess the immunological significance of these HBA spacer domains and their role in clearance of Ots from Indian patients.

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“…Although chiggers (family Trombiculidae ) are thought to be the true reservoir of O . tsutsugamushi , rodents including mice and rats also play an important role in the transmission of Orientia bacteria 43,44 . Even though it is the only recognized species within the genus Orientia , O .…”

Section: Discussionmentioning

confidence: 99%

Epidemiology and Diversity of Rickettsiales Bacteria in Humans and Animals in Jiangsu and Jiangxi provinces, China

Feng²,

Liao

et al. 2019

Sci Rep

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Diseases caused by Rickettsiales bacteria are a global public health problem. To better understand the diversity and origins of Rickettsiales infection in humans and animals, we sampled 134 febrile patients, 173 rodents and 43 shrews, as well as 358 ticks, from two cities in Jiangsu and Jiangxi provinces, China. Our data revealed a relatively high prevalence of scrub typhus cases in both localities. In addition, both serological tests and genetic analysis identified three patients infected with Anaplasma bovis, Rickettsia monacensis, and Orientia tsutsugamushi bacteria. Molecular epidemiological investigation revealed the co-circulation of multiple species of Rickettsiales bacteria in small mammals and ticks in both provinces, potentially including novel bacterial species. In sum, these data demonstrate the ongoing importance of Rickettsiales infection in China and highlight the need for the regular surveillance of local arthropods, mammals and humans.

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Prevalence and Phylogenetic Analysis ofOrientia tsutsugamushiin Rodents and Mites from Central India

Cited by 17 publications

References 45 publications

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

Complexity of type-specific 56 kDa antigen CD4 T-cell epitopes of Orientia tsutsugamushi strains causing scrub typhus in India

Epidemiology and Diversity of Rickettsiales Bacteria in Humans and Animals in Jiangsu and Jiangxi provinces, China

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