High toxocariasis seroprevalence in a tri-border indigenous community (Brazil, Paraguay and Argentina): A One Health perspective.

Toxocariasis, a neglected parasitic zoonosis, has mostly affected vulnerable populations of subtropical and tropical regions worldwide. In addition to vulnerability, indigenous communities have long existed before bordering areas, particularly in South American countries, leading to cultural isolation, migratory and environmental concerns, lately associated to low human infrastructure and lack of healthcare policies. Accordingly, the study herein has serosurveyed anti-Toxocara spp. antibodies in indigenous persons, and surveyed Toxocara spp. in their dog and soil samples from a Guarani-Mabyá indigenous community located in a tri-border area of Brazil, Paraguay and Argentina. Overall, seropositivity was detected in 246/258 (95.3 %; 95 % CI: 92.1-97.3) indigenous persons, with no statistically associated risk factor to seropositivity, likely due to the highest human toxocariasis seroprevalence reported to date worldwide. Although detected in only 8/124 (6.5 %) dog feces samples, Toxocara spp. eggs were present in 13/42 (30.9 %) soil samples of common areas and 17/32 (53.1 %) of households, molecularly identified as T. canis by DNA amplification. The significant number of infective Toxocara spp. eggs found in the soil samples has reinforced the role of daily environmental exposure in sustaining transmission within this community, which may reflect the pattern of disease status in other nearby indigenous communities. Moreover, migratory behavior of Guarani ethnicity across the tri-border may have spread infection to other border indigenous communities of Brazil, Paraguay and Argentina.