Prevalence and phylogenetic analysis of Cryptosporidium in pigs in eastern China.

Faecal samples from 1488 pigs were collected from six pig farms in Jiangsu province and Shanghai city, eastern China, stained by the modified acid-fast staining technique (MAFS) and observed by light and phase contrast microscopy to identify Cryptosporidium oocysts. A total of 178 (12%) positive animals were detected. Three randomly selected MAFS-positive samples from each farm were further analysed by reverse-transcription polymerase chain reaction (RT-PCR) using primers designed to amplify DNA fragments from the small subunit ribosomal RNA (SSU rRNA) gene. PCR products from two positive samples were sequenced. Phylogenetic analysis and a distances matrix generated from these sequences showed that the isolates belonged to the species C. parvum, and were most similar to the C. parvum'mouse' genotype. The identification of this C. parvum genotype in pigs has not been reported previously. These findings are discussed in the context of the epidemiology of Cryptosporidium on pig farms.