Molecular and biological characterisation of Cryptosporidium in pigs

Objective. Genetic and biological characterisation of 12 isolates of Crypto sporidium from pigs and comparing them with Cryptosporidium isolates from h umans and cattle. Design. Cryptosporidium isolates from pigs were compared with those obtaine d from human and cattle using rDNA sequence analysis. The infectivity of tw o of the porcine isolates was determined in neonatal mice and the clinical history of the infected pigs recorded. Results. Pig-derived isolates of Cryptosporidium exhibited two distinct gen otypes; a porcine genotype and a bovine genotype, which is common to cattle and other livestock. The porcine genotype did not produce any infection in neonatal mice whereas the bovine genotype did. Conclusion. Two distinct genetically and biologically differing strains of Cryptosporidium appeared to be associated with acute diarrhoea in pigs. Whe ther Cryptosporidium was a primary or secondary pathogen is unclear but war rants further investigation. As the bovine genotype is known to infect huma ns, the results suggest that pigs can act as reservoirs of cryptosporidial infections for humans and other livestock. The zoonotic potential of the pi g-adapted genotype is uncertain and requires further study.