Gastrointestinal parasitism in endangered Black Lion Tamarins (Leontopithecus chrysopygus) across anthropized Atlantic Forest fragments

Despite conservation efforts, deforestation continues to fragment forest habitats, progressively bringing humans into closer contact with wildlife. These close human-wildlife interfaces pose several problems, including increased human disturbances to wildlife that may negatively affect their survival, or heightened risks of bidirectional disease transmission. Such ‘One Health’ contexts are particularly present in the State of São Paulo, Brazil, where the landscape is constituted of a patchwork of pastures, crops, urban areas and small forest fragments of the Atlantic Forest. These remnant forest fragments are home to numerous endangered species, including the endemic Black Lion Tamarin (BLT, Leontopithecus chrysopygus). This species being endangered, gaining insight in its health status in such ‘One Health contexts’ is paramount, yet remains largely unexplored. This study presents the first investigation of gastrointestinal parasitic infections in four wild BLT groups across three sites with varying degrees of human disturbance. A total of 83 fecal samples were collected non-invasively from the soil and analysed fresh using three complementary coproparasitological techniques (Willis, Faust, and Hoffmann) to detect eggs, oocysts, and larvae. Parasites were detected in 43% of samples, with 29% exhibiting multi-infections. Identified taxa included members of the class Cestoda and the phylum Acanthocephala, along with eight helminth superfamilies such as Oxyuroidea. Although preliminary analysis did not reveal statistically significant differences in infection rates among study sites (p = 0.49), these pioneering results provide valuable baseline data on gastrointestinal parasitism in this endangered primate living within anthropized habitats. While taxonomic limitations preclude definitive conclusions about zoonotic transmission pathways, the study highlights the need for future research to better assess parasite diversity and potential cross-species transmission.