Long-Term Monitoring of the Seasonal Abundance of Basidiobolus spp. in Gecko Feces in KwaZulu-Natal (South Africa)

The fungal genus Basidiobolus is typically associated with ectothermic animals such as amphibians and reptiles. In rare cases, it can cause infections in humans, which are often misdiagnosed. Although usually restricted to tropical and subtropical countries, infections have recently been more frequently reported in hot-dry regions such as Arizona and Saudi Arabia. Reptiles such as geckos are known to shed Basidiobolus spp. via feces and frequently live in close proximity to humans. To establish the frequency and burden of Basidiobolus spp. released by geckos in a suburban location, we regularly quantified viable Basidiobolus units per gram of feces from indoors and outdoors over 3.5 years between 2018 and 2022 using a selective medium. Geckos were shedding Basidiobolus spp. in all seasons, with most counts established ranging between 5.0 and 6.5 log(10) cfu per gram. Statistically significant seasonal differences per location were only observed for the outside winter counts and, apparently, correlated to lower temperatures, while inside counts showed no seasonal difference. Overall, counts for droppings collected outdoors were significantly higher than counts for droppings collected indoors. Our data confirm that geckos, which frequently enter homes and are global invaders, are a regular source of this fungus.