Comparative evaluation of conventional diagnostic methods for detection of bovine cryptosporidiosis

Cryptosporidium is an important enteropathogen that causes diarrhoea in diary calves. Keeping in view of the importance, there is a need for simple and inexpensive diagnostic and screening tests for the detection of Cryptosporidium infection in dairy calves. In the present study, 4 conventional coprological detection methods were compared and evaluated in detection of Cryptosporidium oocysts in dung samples of dairy calves. Direct smear (DS) examination detected 21 positives (3.15%) for Cryptosporidium oocysts, out of 667 samples screened. In faecal concentration techniques, sugar floatation (SF) and formal-ethyl acetate (FEA) methods detected 39 (5.85%) and 41 (6.15%) positives, respectively. A total of 74 positives were detected by modified Ziehl-Neelsen (mZN) staining technique with a prevalence of 11.09%, showing that mZN technique as the most sensitive method of detecting Cryptosporidium oocysts. Statistical analysis revealed that highly significant difference was observed between DS and SF, FEA and mZN techniques. Inclusive and exclusive detection of Cryptosporidium oocysts by various conventional microscopic methods were recorded. In conclusion, among the conventional microscopic methods followed in the present study, mZN staining technique was more sensitive for detection of Cryptosporidium infection. Further, mZN staining technique is more appropriate and recommended to its use for developing countries like India for diagnosis of Cryptosporidium infection in bovine calves.