Detection of zoonotic Cryptosporidium parvum in invasive beavers from southern Tierra del Fuego, Chile

Since their introduction to Tierra del Fuego in 1946, invasive beavers ( Castor canadensis ) have expanded their population and caused extensive environmental degradation across the sub-Antarctic region. Beaver dams have profoundly impacted peatlands, mature sub-Antarctic forests, and watercourses. Here, we report a pathogen in invasive beavers in Patagonia and discuss their potential role as a reservoir of waterborne zoonotic pathogens. We detected Cryptosporidium through microscopy using the Ziehl-Neelsen staining technique in beavers collected from southern Tierra del Fuego. Out of the 105 beavers examined, three tested positive to optical microscopy, which were then identified molecularly as Cryptosporidium parvum by sequence analysis of the 18S ribosomal DNA (rDNA), showing a 2.87% infection rate. Given the potential impacts of Cryptosporidium parvum upon native species, wildlife, and human health, this finding highlights the potential risks associated with the ongoing expansion of beavers into other areas of the sub-Antarctic region. A potential role of invasive beavers as reservoirs of zoonotic Cryptosporidium spp. in Patagonia emphasizes the unknown consequences of human-introduced exotic species on pristine ecosystems.