Development of a real-time PCR assay for detection of Cryptosporidium canis in dog fecal samples.

Cryptosporidiosis is an emerging zoonotic disease caused by the worldwide distributed parasitic protozoa Cryptosporidium spp. The host-adapted species Cryptosporidium canis is most frequently found in dogs, although human infections with this species have been described. This study aimed to develop a real-time PCR targeting the HSP70 protein gene for C. canis DNA detection in dog fecal samples collected from two municipalities in the state of São Paulo, Brazil. Furthermore, the occurrence of Cryptosporidium spp. and. C. canis was also determined by nested PCR. Fecal samples from 367 dogs (21 puppies and 346 adults) were purified by water-ether sedimentation. A real-time PCR protocol targeting the HSP70 gene for the species-specific detection of C. canis was developed and compared with nested PCR results. Real-time PCR identified C. canis in 15.3% (58/367) samples. Nested PCR revealed that 10.4% (38/367) of samples were positive for Cryptosporidium spp. All sequenced 18S rRNA amplicons were C. canis. There was a higher prevalence of Cryptosporidium spp. and C. canis in puppies compared to adult dogs. No non-specific amplification was observed in C. canis specific real-time PCR assay.