PATTERNS OF CRYPTOSPORIDIUM OOCYST SHEDDING IN CALVES AND A COMPARISON OF 2 DIAGNOSTIC METHODS

Cryptosporidium spp. oocyst shedding was observed in calves from appro ximately 1 to 30 days of age. Oocysts were detected by either the Kiny oun acid-fast staining technique (microscopic examination-ME) or a com mercially produced enzyme immunoassay (EIA). Test concordance between the two detection methods was determined. The mean (+/- SD) number of days to detection of cryptosporidial oocysts was 9.52+/-1.92 for the M E and 9.83 +/- 3.19 for the EIA. No significant difference between the means was found (P = 0.17). The period prevalence of cryptosporidiosi s was 100% in calves from 1 to 30 days of age. The overall agreement b etween the ME and EIA was 72%, with a kappa value of 0.42 (SE +/- 0.05 ). McNemar's test indicated that the proportion of tests determined po sitive by the two methods was not equal (P < 0.01). The findings or th is study indicate moderate agreement between the two diagnostic method s, with the EIA being the more sensitive of the two. However, in most cases the herd-level determination of cryptosporidiosis requires minim al sample sizes and is more economically and easily accomplished by th e ME method of detection.