Abstract
Calves remain one of the most important reservoirs of diarrheagenic agents to their human contacts. This study investigated the role of calves in transmission of Salmonella, Escherichia coli and Cryptosporidium spp., to human. Fecal samples collected from 120 diarrheic calves up to 6 months of age and 100 diarrheic stool samples collected from human contacts from El-Behira province, Egypt were examined. The detection of Salmonella and E. coli was done by conventional bacteriological methods, while the Cryptosporidium spp. oocyst was screened by modified Ziehl-Neelsen acid-fast microscopy. It was found that the detection rates of Salmonella, E. coli and Cryptosporidium spp. in diarrheic calves were 10, 20.8 and 9.2%, respectively while in human contacts were 5, 17 and 7%, respectively. Serological identification of isolates of Salmonella clarified the presence of S. Enteritidis, S. Typhimurium, S. Meleagridis, S. Anatum and S. Lagos while that of E. coli revealed the presence of serotypes O158, O18 and O114. Statistical analysis showed that there was a significant association between the rates of isolation of Salmonella in relation of different age groups in calves while there was no significant association between other variables. The results of this study confirmed the significant role of diarrheic calves as sources of human infection with diarrheagenic agents in El- Behira province that necessitate the need for establishing a plan for control of infectious diarrhea in calves.

Key words: Salmonella, E. coli, Cryptosporidium, Calves, Humans, Isolation