Ocorrência de protozoários zoonóticos em animais silvestres e águas brutas no contexto de saúde única no Sul do estado do Rio Grande do Sul

Abstract

This study aims to deploy epidemiological surveillance for zoonotic pathogens in wild animals in the southern region of Rio Grande do Sul, Brazil. Its relevance is based on the estimate that more than 60% of known human pathogens are zoonotic, making investigation crucial due to increased interspecies interaction caused by factors like urban expansion and climate change. This study investigated the occurrence of zoonotic pathogens of public health relevance — Cryptosporidium spp., Cystoisospora spp., Giardia lamblia, Leishmania spp., and Trypanosoma spp.— in wild animals and raw water in the South of Rio Grande do Sul, Brazil. This was done under the One Health perspective as a strategy for epidemiological surveillance and for understanding the biological reservoirs and dynamics of these protozoa. Tissue samples from road-killed wild animals, as well as surface water from rivers and streams in the Pelotas microregion, were analyzed using molecular diagnostic techniques to identify the presence of the protozoa. The results revealed a high prevalence of Trypanosoma cruzi (80% of the analyzed animals), encompassing a wide diversity of hosts, including mammals from different ecological niches and birds. This highlights a robust enzootic cycle with the potential for spillover to humans and domestic animals. Leishmania spp. was also detected in animals at the Taim Ecological Station and in the rural area of Piratini-RS, localities traditionally considered of low prevalence for leishmaniasis. This suggests a possible geographical expansion of the disease’s sylvatic cycle in the extreme south of Brazil. Concurrently, the detection of Cystoisospora spp. and Giardia lamblia was continuous across all raw water collection points. However, their occurrence varied significantly, remaining between 25% and 62.5% across the different sites. These findings, combined with the detection of waterborne protozoa in both fauna and multiple raw water points, reinforce the importance of integrating environmental and faunal monitoring into epidemiological surveillance. The study provides critical data for analyzing the geographical distribution of pathogens, supporting the formulation of preventative and control strategies aligned with One Health principles, aiming to reduce risks to human health and preserve ecosystem integrity.