Background & objectives: Scrub typhus, an acute febrile Rickettsial disease is caused by the bacterial pathogen Orientia tsutsugamushi which is spread by the bite of infected chigger mite vectors belonging to the family Trombiculidae. A study was undertaken to find out the prevalence of scrub typhus among the indigenous population from Nilgiris, Tamil Nadu. Methods: This study was conducted among 214 patients with fever of unknown aetiology and a recent history of febrile illness attending the Nilgiris Adivasi Welfare Association medical facilities available at Nilgiris district, Tamil Nadu. Serum samples were tested for scrub typhus IgM enzyme-linked immunosorbent assay. Results: Overall, 13 (6.07%) of the 214 samples tested were positive for scrub typhus. This is the first seroprevalence report of scrub typhus from the indigenous people belonging to Irula, Kurumba, Paniyar, and Kota tribes from the Nilgiris district, Tamil Nadu. Interpretation & conclusions: Early diagnosis and effective management will protect this indigenous population from this disease. This report would help in creating awareness regarding scrub typhus infection among clinicians and public health authorities in the region and take appropriate measures for treatment and control.

Background & objectives: Scrub typhus, caused by Orientia tsutsugamushi present in small mammals harbouring the ectoparasites. A study was undertaken to detect the pathogen present in small mammals and its ectoparasites in the scrub typhus-reported areas. Methods: The small mammals (rodents/shrews) and its ectoparasites were screened for O. tsutsugamushi using nested PCR amplification of the groEL gene. Small mammals were collected by trapping and screened for ectoparasites (mites, ticks and fleas) by combing method. Results: All the chigger mites collected were tested negative for O. tsutsugamushi. Interestingly, adult non-trombiculid mites (Oribatida sp., Dermanyssus gallinae), fleas (Xenopsylla astia, X. cheopis, Ctenophalides felis and Ctenophalides sp.) and ticks (Rhipicephalus sanguineus, R. haemaphysaloides) screened were found to be positive for O. tsutsugamushi, which the authors believe is the first report on these species globally. Bandicota bengalensis with O. tsutsugamushi infection is reported for the first time in India. The O. tsutsugamushi groEL sequences from the positive samples were similar to the reference strains, Karp and Ikeda and phylogenetically clustered in clade IV with less evolutionary divergence. The blood samples of Rattus rattus, Suncus murinus and B. bengalensis collected from this area were tested positive for O. tsutsugamushi; interestingly, the sequence similarity was much pronounced with their ectoparasites indicating the transmission of the pathogen to host or vice versa. Interpretation & conclusions: The outcome of the present investigations widened our scope on the pathogens present in ectoparasites and rodents/shrews from this area. This will help to formulate the required vector control methods to combat zoonotic diseases.

The main goal of this investigation was to record the ectoparasites living on rodents in scrub typhus endemic areas of Kerala state, India. Rodents captured alive using Sherman and wonder traps from four diverse habitations revealed, a total of 59 rodents/shrews constituted by 5 host species from families Muridae and Soricidae. In total, 1135 ectoparasites were collected on these rodents/shrews and were identified representing 23 species from 10 genera in 4 families Trombiculidae, Laelaptidae, Ixodidae and Pulicidae. Dominant insectivore species was Suncus murinus (57.6%). 42 (71.2%) rodents and shrews were found to be plagued with at least one of the 23 species of ectoparasite harvested. Mites belonging to the family Trombiculidae were the predominant ectoparasite species collected. Study revealed Tatera indica (35.5%) as the primary host harboring the chigger mites. Xenopsylla cheopis and Xenopsylla astia the flea species important vectors for the transmission of zoonotic diseases such as Leptotrombidium deliense, Schoengastiella ligula and Echinolaelaps echidninus were recorded. Twenty species of mites were reported for the first time in Kerala which add knowledge on the ectoparasites distribution.

Scrub typhus cases have been reported in Madurai, but very little is known about the distribution patterns of ectoparasites on rodents and shrews in the Madurai district. To determine the chigger vectors of scrub typhus, Rattus rattus, R. norvegicus, Mus musculus, and Suncus murinus were collected from these areas and the prevalence and mean intensity were calculated as 40% & 14.8 ± 3.9 for chiggers. Mites were collected from burrow soil samples. The chiggers Leptotrombidium deliense and Schoengastiella ligula, both known as vectors for the transmission of Orientia tsutsugamushi in India, were recorded in this study. In addition, Rhipicephalus sanguineus ticks, a putative vector of Indian tick typhus and canine ehrlichiosis, and the oriental rat flea Xenopsylla cheopis, a known vector of the plague pathogen Yersinia pestis, were also reported. They have high zoonotic potential and have been implicated in the transmission of the aforementioned emerging zoonotic diseases. Parapathi is a typical scrub typhus village with lots of rat burrows found around many houses and many reported scrub typhus cases. Rodents and shrews collected from these areas harboured vectors of medical and veterinary importance and act as endemic reservoir for transmitting zoonotic diseases which requires urgent attention for its control. http://www. zoobank.org/urn:lsid:zoobank.org:pub:5EFDD3BC-B9BA-4595-A02E-8AAEB4E7D755