Spotted fever Rickettsia and relapsing fever Borrelia in rodents from southern India

Abstract Bacterial zoonoses constitute a substantial fraction of emerging infectious diseases. In this study, we investigated the presence of pathogenic bacterial genera— Rickettsia, Borrelia, Orientia, Leptospira , and Coxiella —in rodents from southern India. We detected low circulation of Rickettsia (7.26%), Borrelia (6.45%), and Leptospira (0.8%), whereas Orientia and Coxiella were not detected in the rodents sampled. Notably, we observed contrasting patterns of tissue association, with rickettsiae detected exclusively in pooled organ tissues and borreliae detected only in blood, suggesting the influence of pathogen biology in detection probabilities. Our phylogenetic analyses further revealed spotted fever group rickettsiae and relapsing fever group borreliae in both synanthropic and forest-associated rats, highlighting a potential transmission risk to people and livestock in the region. By revealing the circulation of zoonotic bacteria in new host species, this study underscores the need for systematic surveillance of wildlife to better characterize bacterial diversity and its public health implications.