Detection of <i>Cryptosporidium</i> and <i>Giardia duodenalis</i> in Reptiles in Thailand

Cryptosporidium spp. and Giardia duodenalis are significant intestinal protozoan parasites affecting humans and animals worldwide. These infections are transmitted through the faecal-oral route, by contaminated water, food or close contact with infected hosts. The zoonotic risk of transmission from reptiles is considered low; yet, limited research exists regarding Cryptosporidium and Giardia infections in these animals. This study investigated the presence of Cryptosporidium spp. and G. duodenalis in reptile faecal samples from a breeding farm in the Chonburi Province, Eastern Thailand. The test population included 363 iguanas, 50 tortoises, 79 bearded dragons and nine snakes. DNA extraction from faecal samples was performed, followed by nested PCR for Cryptosporidium and G. duodenalis, and all positive samples were sequenced for molecular characterisation. Cryptosporidium and G. duodenalis were detected in 13 and 25 out of 501 faecal samples, respectively. Specifically, seven of 363 iguana samples and six of 79 bearded dragon samples tested positive for Cryptosporidium. Cryptosporidium avium was found in 11 samples, and one sample revealed Cryptosporidium serpentis; the remaining sample could not be identified at the species level. For G. duodenalis, 15 of 363 iguanas tested positive, along with six of 79 bearded dragons, two of 50 tortoises and two of nine snakes. Only G. duodenalis assemblage B was identified in positive samples. This study provides epidemiological information on the infection rate and distribution of species of Cryptosporidium and Giardia in a breeding reptile farm in Chonburi Province, Eastern Thailand, and the findings are discussed in the context of the scientific literature. SUMMARY: This study represents one of the largest surveys on Cryptosporidium and Giardia duodenalis in reptiles. Cryptosporidium avium, typically associated with avian hosts, was the predominant Cryptosporidium species identified in iguanas and bearded dragons. Giardia duodenalis assemblage B, known for its zoonotic potential, was the primary assemblage found in iguanas.