Identification of novel and zoonotic Cryptosporidium species in marine fish

Little is known about the prevalence and genotypes of Cryptosporidium in fish. The present study investigated the prevalence of Cryptosporidium species in cultured fingerlings (n = 227), wild freshwater (n = 227) and wild marine/estuarine species (n = 255) of fish in Western Australia by PCR amplification at the 18S rRNA locus. Results revealed a low prevalence of Cryptosporidium infection in fish hosts; 0.8% (6/709). Four species of Cryptosporidium were identified including C. parvum, C. xiaoi and pig genotype II in whiting (Sillago vittata) and a novel Cryptosporidium spp. in mullets (Mugil cephalus). The identification of zoonotic species of Cryptosporidium in fish indicates that future research to gain a better understanding of the public health impacts is warranted. The detection of the protozoa in fish may also be a good sentinel for environmental contamination or ecosystem health.