NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

Cryptosporidiosis

Cryptosporidiosis has recently come to national attention as a potential cause of water-borne disease in humans, due to contamination of the water supply by infected animal faeces. However, as well as being a potential human disease, cryptosporidiosis is also a significant cause of disease in young farm animals.

What is Cryptosporidiosis?

Cryptosporidiosis is caused by infection with the single-celled parasite (not bacteria) Cryptosporidium parvum. This parasite is found in many mammals including lambs, calves, goat kids, piglets and humans. Research so far has shown two basic types, one the bovine type which affects most species, and a second human type which causes disease in humans only. Outbreaks of human disease, where large numbers of people are affected, are usually water-borne and usually associated with the bovine type of cryptosporidium. Individual sporadic cases of cryptosporidiosis in humans are mostly (around 60%) associated with the human type of cryptosporidium.

Cryptosporidiosis is usually seen in calves between one and two weeks of age. It is very in animals older than a month old, because by this age most animals will have become immune to infection.

Clinical Signs

1) Diarrhoea – profuse watery and green, occasionally bloody

2) Colic and pain

3) Depression, loss of appetite, weight loss

Many infected calves will not develop diarrhoea, the reason for this is not known

In many cases cryptosporidia is seen with other diseases, particularly rotavirus. In this case disease is often more severe with more affected calves.

Diagnosis

· On the clinical signs described above

· Examination of diarrhoea for the presence of cryptosporidia. However, care must be taken when interpreting these results and it is best to consult a veterinarian in suspect cases

Treatment

· Many cases will recover without treatment.

· If calves become dehydrated then electrolytes should be given.

· If disease is severe, halfuginone can be used to reduce disease severity and prevent spread to other animals. However this product needs to be used with advice from your vet as it can cause problems if not used correctly, particularly in ill animals

· All calves with diarrhoea should be separated from clinically normal calves, to reduce contamination of environment with oocysts.

Prevention

To achieve effective control of cryptosporidia, good management and hygiene is vital. The major source of cryptosporidia is left-over oocysts from previously infected calves. These oocysts can be killed by freezing and by composting, but they are very resistant to disinfectants. Hot washing of surfaces followed by thorough drying is effective. Most commercial disinfectants are ineffective at recommended safe concentrations, except for some ammonia-based disinfectants.

Prevention of disease is therefore based on:

1) Regularly moving feed and water troughs

2) Preventing faecal contamination of feed and water troughs, by raising or covering

3) Increasing the bedding to reduce contamination

4) Clean and disinfect all buildings with products that kill oocysts

5) Mass medication can be used as a preventative, but it is no substitute for improving management.

Richard Laven PhD BVetMed MRCVS