Persistent infection in a dairy herd with an unusual genotype of bovine Cryptosporidium parvum.

On two occasions, we identified Cryptosporidium parvum with an unusual banding pattern after restriction enzyme digestion of Cryptosporidium oocyst wall protein PCR fragments. The samples originated from a single farm with calf diarrhoea. The Cryptosporidium oocyst wall protein PCR fragment sequence revealed a point mutation in one of the recognition sites for RsaI. Our subgenotyping showed that samples from both samplings shared the same MS1 and GP15 alleles. Analysis of the TP14 microsatellite was less sensitive, and results were only obtained from two samples. Both had the same allele. This is, to our knowledge, the first description of a C. parvum with this Cryptosporidium oocyst wall protein genotype. More importantly, the genotype seems to be stable over time since we could detect it again among newborn animals almost 1 year after it was first identified.