Detection of oocysts and IgG antibodies to Cryptosporidium parvum in asymptomatic adult cattle.

Infection by Cryptosporidium was detected in 94 (71.75%) asymptomatic adult cattle from 131 fecal samples examined microscopically. In two cases Cryptosporidium oocysts were observed which were distinctly larger (5.5-6.5 microns x 6.6-7.0 microns) than those we had seen in the majority of feces examined (4.0-4.5 microns x 4.0-4.5 microns) and these specimens were considered to be Cryptosporidium muris; it is possible that the other oocysts should be considered as Cryptosporidium parvum. The seroprevalence of IgG antibodies to Cryptosporidium was 63.35% as detected by indirect fluorescent antibody test (IFAT) and 51.41% by enzyme-linked immunosorbent assay (ELISA). In 27 cases, the presence of IgG antibodies to Cryptosporidium (as tested by IFAT and ELISA) in serum samples was correlated with oocyst excretion.