Wombats and domestic livestock as potential vectors of Cryptosporidium and Giardia in an agricultural riparian area

Emerging pathogenic diseases are a significant burden on global economies and public health administrators. In Australia, the pathogens Giardia and Cryptosporidium are widespread in riparian areas subject to urban or agricultural contamination. Bare-nosed wombats (Vombatus ursinus) occur at relatively high densities alongside domestic cattle in agricultural riparian areas in south-eastern Australia and may transmit protozoan pathogens. We assessed the distribution of wombat scats and cattle pats on streambanks and screened them for the presence of Giardia and Cryptosporidium. The density of wombat scats declined with increasing distance from water while the cover of cattle pats increased with distance from water, but only at sites subjected to low cattle usage. We were unable to find any Cryptosporidium species or genotypes known to infect humans in either wombat or cattle faeces. One cattle sample contained Cryptosporidium bovis, a cattle-specific organism unlikely to be zoonotic. Giardia duodenalis (Assemblage E), a non-zoonotic pathogen, was detected in four cattle samples, but no wombat samples tested positive for Giardia. Our results suggest that while wombats represent a low-pathogen risk there is a need for consistent monitoring of potentially harmful waterborne and chlorine-resistant Giardia and Cryptosporidium pathogens in drinking-water catchments.