Cryptosporidium spp. in wild and captive Australian flying foxes (genus: Pteropus)

Spillover of zoonotic pathogens from wildlife to humans is a primary threat to global health, but the potential impacts of reverse pathogen transmission (zooanthroponosis) is still largely unexplored. Increasing establishment of wildlife species in regional and urban Australia potentially increases risk of human-borne pathogen spillover at the human/wildlife interface. To explore this issue, the occurrence of the protozoan parasite Cryptosporidium was investigated in urbanised flying fox populations. Cryptosporidium infects a wide range of vertebrates, with species varying in host specificity. In humans, C. hominis and C. parvum are responsible for the majority of infections. PCR screening of faecal samples (n = 281) from seven wild and two captive flying fox populations identified the presence of Cryptosporidium in 3.2% of samples, with a prevalence of 1.7% in wild versus 6.3% in captive individuals (χ² = 3.708, DF = 1, p= 0.054). Using multilocus sequencing (18s rRNA, actin and gp60) C. hominis was identified in captive animals (n = 2) and four novel Cryptosporidium genotypes in wild and captive animals (n = 7). This is the first study to report the presence of Cryptosporidium spp. in Australian flying foxes and findings indicate zooanthroponotic transmission of Cryptosporidium from humans to flying foxes.