PROTOZOAN, BACTERIAL AND VIRAL PATHOGENS, FARM ANIMAL WASTES AND WATER QUALITY PROTECTION - 2ND YEAR RESEARCH REPORT TO MAFF & SOAFD On farm detection of Cryptosporidium parvum in cattle, calves and environmental samples.
Report No DWI0750

SUMMARY

A dairy farm with a long history of clinical Cryptosporidiosis in its calves was intensively monitored to examine the spread of infection and number of oocysts shed by neonatal calves throughout the calving season. Oocysts were detected using faecal smears stained with phenol auramine and viewed under incident fluorescent light microscopy. Enumeration of oocysts was performed by dilution counting using an improved Neubauer Haemocytometer. Samples containing small numbers of oocysts were examined using ether sedimentation concentration techniques. 96 per cent of the calves born developed clinical Cryptosporidiosis with oocyst numbers ranging from 24 to 9.11*10^8/gram wet weight faeces. Faecal samples from adult cattle were also examined for presence or oocysts using ether sedimentation techniques, followed by staining with a commercial monoclonal antibody stain, and viewed by fluorescent microscopy. A significant number of adult cattle were found to be shedding small numbers of oocysts in their faeces (<21 oocysts/gram wet weight faeces). Further studies were conducted to examine the dissemination or oocysts from the farm environment to the surrounding water courses by taking weekly water samples from the main farm drainage outlets and examining these for presence of oocysts using a commercial monoclonal antibody. Results to date indicate oocyst concentrations between 0.06 oocysts/litre and 19.4 oocysts/litre.

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