Comparative evaluation of five diagnostic methods for detection of Cryptosporidium spp. in diarrheic bovine calves.

Cryptosporidium spp. are significant enteric protozoan parasites affecting neonatal calves, and they are known to potentially have zoonotic implications. An accurate diagnosis is essential for effective disease control and surveillance. This cross-sectional study comparatively evaluated five diagnostic techniques; direct wet smear, Leishman staining, modified Ziehl-Neelsen (mZN) staining, phenolic auramine staining, and polymerase chain reaction (PCR) for detection of Cryptosporidium spp. in diarrheic bovine calves from western Uttar Pradesh, India. During June 2003 to May 2004, among 200 faecal samples from calves aged ≤3 months, 33 positive samples were identified using PCR targeting the COWP gene yielding a molecular prevalence of 16.5%. Using PCR as the reference standard, the sensitivities of wet smear, Leishman, mZN, and auramine were 60.6% (wet smear), 78.8% (Leishman), 90.9% (mZN), and 97.0% (auramine), while the specificities ranged from 94.0% to 99.4%. Auramine staining demonstrated almost perfect agreement with PCR (κ = 0.96), followed by mZN staining (κ = 0.94). These findings confirm the endemic occurrence of Cryptosporidium infection in young calves in this region. Phenolic auramine staining provides a highly reliable and practical alternative to PCR under regional laboratory conditions.