Candasamy Sadanandane, Ayyanar Elango, Devaraju Panneer, Kumar Ashwani, Zaman Kamran, Bhaskar Mishra Bhuwan, Srinivasan Lakshmy, Purushothaman Jambulingam
ICMR-Vector Control Research Centre (ICMR-VCRC), Puducherry, India.
ICMR-Regional Medical Research Centre (ICMR-RMRC), Gorakhpur, India.
Med Vet Entomol. 2024 Mar;38(1):23-37. doi: 10.1111/mve.12694. Epub 2023 Sep 21.
Outbreaks of acute encephalitis syndrome (AES) with unknown aetiology are reported every year in Gorakhpur district, Uttar Pradesh, India, and Orientia tsutsugamushi, the rickettsial pathogen, responsible for scrub typhus has been attributed as the primary cause of AES problem. However, information on the prevalence of other rickettsial infections is lacking. Hence, this study was carried out to assess any occurrence of tick- and flea-borne rickettsial agents in villages reporting AES cases in this district. In total, 825 peridomestic small mammals were trapped, by setting 9254 Sherman traps in four villages with a trap success rate of 8.9%. The Asian house shrew, Suncus murinus, constituted the predominant animal species (56.2%) and contributed to the maximum number (87.37%) of ectoparasites. In total, 1552 ectoparasites comprising two species of ticks and one species each of flea and louse were retrieved from the trapped rodents/shrews. Rhipicephalus sanguineus, the brown dog tick, was the predominant species retrieved from the trapped rodents/shrews, and the overall infestation rate was 1.75 per animal. In total, 4428 ectoparasites comprising five tick species, three louse species and one flea species were collected from 1798 domestic animals screened. Rhipicephalus microplus was the predominant tick species collected from the domestic animals. The cat flea, Ctenocephalides felis, constituted 1.5% of the total ectoparasites. Of all the ectoparasite samples (5980) from domestic animals and rodents, tested as 1211 pools through real-time PCR assays, 64 pools were positive for 23S rRNA gene of rickettsial agents. The PCR-positive samples were subjected to multi-locus sequence typing (MLST). In BLAST and phylogenetic analysis, the ectoparasites were found to harbour Rickettsia asembonensis (n = 9), Rickettsia conorii (n = 3), Rickettsia massiliae (n = 29) and Candidatus Rickettsia senegalensis (n = 1). A total of 22 pools were detected to have multiple rickettsial agents. The prevalence of fleas and high abundance of tick vectors with natural infections of rickettsial agents indicates the risk of transmission of tick- and flea-borne rickettsial diseases in rural villages of Gorakhpur. Further epidemiological studies are required to confirm the transmission of these agents to humans.
印度北方邦戈勒克布尔地区每年都会报告病因不明的急性脑炎综合征（AES）疫情，而恙虫病立克次氏体病原体——恙虫东方体，被认为是AES问题的主要病因。然而，关于其他立克次氏体感染的流行情况缺乏相关信息。因此，本研究旨在评估该地区报告AES病例的村庄中是否存在蜱传和蚤传立克次氏体病原体。通过在四个村庄设置9254个谢尔曼陷阱，共捕获了825只家畜周围的小型哺乳动物，捕获成功率为8.9%。亚洲家鼩鼱是主要的动物种类（占56.2%），也是体外寄生虫数量最多的动物（占87.37%）。从捕获的啮齿动物/鼩鼱身上共采集到1552只体外寄生虫，包括两种蜱、一种跳蚤和一种虱子。血红扇头蜱是从捕获的啮齿动物/鼩鼱身上采集到的主要蜱种，总体感染率为每只动物1.75只。从1798只被筛查的家畜身上共采集到4428只体外寄生虫，包括五种蜱、三种虱子和一种跳蚤。微小牛蜱是从家畜身上采集到的主要蜱种。猫蚤占体外寄生虫总数的1.5%。在家畜和啮齿动物的所有体外寄生虫样本（5980份）中，通过实时PCR检测作为1211个样本池进行检测，其中64个样本池的立克次氏体病原体23S rRNA基因呈阳性。对PCR阳性样本进行多位点序列分型（MLST）。在BLAST和系统发育分析中，发现体外寄生虫携带阿桑博内斯立克次氏体（n = 9）、康氏立克次氏体（n = 3）、马赛立克次氏体（n = 29）和塞内加尔立克次氏体（n = 1）。总共检测到22个样本池含有多种立克次氏体病原体。跳蚤的存在以及带有立克次氏体病原体自然感染的蜱媒数量众多，表明在戈勒克布尔的乡村地区存在蜱传和蚤传立克次氏体疾病传播的风险。需要进一步的流行病学研究来确认这些病原体是否会传播给人类。
