Synanthropic Rodents as Bioindicator of Human Pathogens in a Tourist Area of Brazil

The black rat Rattus rattus is an exotic and synanthropic rodent prominent in Brazil and with high adaptation to urban areas. The species have an omnivorous diet feed on human food resources, potentially becoming infected and spreading infectious agents that cause zoonoses such as leptospirosis, leishmaniosis, Chagas disease, and toxoplasmosis, which are significant public health concerns in the country. We analyzed the epidemiologic profile of R. rattus infected with these agents using molecular diagnostics in the Olivença district, known for its tourism potential, in Ilhéus, Bahia, Brazil. Of 140 animals, the prevalence rates were 30.0% (42) for Leptospira spp., 3.57% (5) for Leishmania spp., and 0.71% (1) for both Trypanosoma cruzi and Toxoplasma gondii. One animal was co-infected with Leptospira interrogans and T. gondii and another with Leptospira spp. and L. (L.) infantum. The high prevalence of Leptospira spp.-infected animals suggests rodents may be a significant infection source for local hosts, as L. interrogans is most common in rodents and humans. Rodents likely become infected through ingestion or contact with contaminated water bodies or food, particularly for Leptospira spp. and T. gondii. It is worth noting that the studied area has beach, high foot traffic, and popular tourist restaurants, which implies the presence of food waste and litter in the environment. This study found synanthropic rodents infected with significant zoonotic agents, indicating their presence in the environment. These agents may not impact the rodent population but can cause serious diseases in humans and other domestic and wild animal species.