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Young calf health problems caused by the small protozoan parasite (Cryptosporidium parvum) are becoming more widespread.

The problem

Cryptosporidiosis as a result of infection with C. parvum generally occurs in calves around 2-10 days old. Once infected, it takes approximately four days for scour to develop, which then usually lasts for 14 days. Affected calves suffer from dehydration, lose weight and become dull and listless. Some may even die. It’s also important to appreciate that humans are also susceptible to infection; usually as a result of handling infected animals or drinking contaminated water.

The effect

Cryptosporidia destroy the cells that line the villi of the small intestine. This reduces the digestive and absorptive capacity of the gut and causes profuse watery diarrhoea. The onset of this diarrhoea usually coincides with the shedding of oocysts, which are fully developed and infectious when shed.

Scour caused by cryptosporidia is evidence that millions of oocysts are being shed. These contaminate the environment and lead to the infection of other calves. However, the older a calf is before being exposed to cryptosporidia, the less severe the signs are likely to be, although they can still get infected and shed oocysts.

Disease management

Halocur® is the only licensed product available for managing cryptosporidiosis. It is especially useful at preventing cryptosporidia spreading through a group of calves. On farms with a history of crytopsporidiosis, newborn calves should be treated within the first 48 hours of life and the once daily dose of 2ml/10kg should be administered for seven consecutive days after feeding. It can also be used for treating calves with cryptosporidia scour symptoms, but administration should start within 24 hours after the onset of diarrhoea.


Despite the resilience of cryptosporidia to common disinfectants, good hygiene is the most effective strategy for reducing oocyst contamination. Housing should be cleaned and disinfected annually and the best time to do this is when the animals are moved out to grazing. Ammonia-based disinfectants work best, but these cannot be used when livestock are still present because of the fumes they give off. Also try steam cleaning to sterilise feeding troughs and calf pens.

After thorough cleaning, keeping buildings empty over the summer so that they dry out will help. The oocysts thrive in a damp environment, but will not survive drying out.

There is no doubt that prevention of cryptosporidia problems relies on good management practices. Calves should be born and reared in a clean, dry environment and, ideally, housed in individual hutches or boxes. Healthy calves need to be separated from sick calves and cared for by different people, using different equipment. Calf rearing areas should not be occupied continuously and must be thoroughly cleaned between batches of calves.

1. ADAS Report: Economic impact of health and welfare issues in beef cattle and sheep in England (p. 35/36).

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