Criptosporidium spp. Oocysts and Giardia spp. cysts in faeces of Capybaras (Hydrochoerus Hydrochaeris) from CChico Mendes Natural Municipal Park, city of Rio de Janeiro, Brazil: potential risk for zoonotic transmission

Capybaras (Hydrochoerus hydrochaeris) are the largest rodents in the world. These animals live in groups and inhabit areas close to rivers, wetlands and lagoons and can live near areas inhabited by humans and domestic animals. Capybaras play an important role in the transmission of etiological agents of zoonoses, such as diseases caused by Cryptosporidium spp. and Giardia spp. This research aimed to investigate the presence of Cryptosporidium spp. oocysts and Giardia spp. cysts in capybara faeces collected in the Chico Mendes Municipal Natural Park, located in the city of Rio de Janeiro, Brazil, evaluating the possible zoonotic risks of diseases caused by these parasitic agents. A total of 30 samples of fresh capybara faeces were collected from different locations in the park. The samples were submitted to spontaneous sedimentation and Ritchie techniques, stained by Ziehl-Neelsen's technique and observed in light microscopy with 100X magnification for oocysts. Giardia spp. cysts were investigated by observing the sediment in preparation between slide and coverslip, in which a drop of Lugol's iodine was added, and observed under light-field microscopy with the 40X objective. Cryptosporidium spp. oocysts and Giardia spp. cysts were observed in all 30 samples, corresponding to a 100% prevalence of infection of these mammals for the investigated protozoa. This extreme rate of contamination is probably related to the continuous exposure of these animals to untreated sewage contamination. Soil contamination of the Chico Mendes Municipal Natural Park with capybara faeces, as well as the persistence of these animals as reservoirs of pathogenic protozoa, points to the risk of zoonotic transmission of Cryptosporidium spp. and Giardia spp. among the local fauna and humans that frequent this recreational site.