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Cryptosporidium

This is a parasite (Cryptosporidium parvum) found world-wide. Symptoms include severe diarrhoea, weight loss and dehydration. It was first recognised as a cause of human disease in the mid 1970's. In the UK it is the 6th commonest cause of diarrhoea. It may be contracted from a number of sources including animals (particularly cattle and sheep) and person to person contact. In recent years, there have been a few outbreaks in which water was the route of infection.

There are seasonal peaks in reported outbreaks of the parasite in humans, the spring peak being associated with the lambing season and scouring that often arises in their early weeks. Farm waste contamination of water supplies may sometimes be the cause.

The Drinking Water Inspectorate have initiated a national programme of research which includes improving the monitoring of and assessing the viability of Cryptosporidium in water supplies and determining the minimum infectious dose for humans.

The main complication of Cryptosporidium is that it can not be controlled by chlorination. However, research has shown that most of it is destroyed during composting because of the high tempertaures reached in the middle of the heap. Even without sohpisticated composting and turning facilities simple storage of composts will significantly reduce viability of the parasite. The longer the slurry is stored the greater the effect.

When infected slurry is applied to land there is a risk that nearby water could be contaminated through drainage or run-off and that humans or animals drinking that water become infected. There is little risk from farmyard manures as long as application is not too close to the waters edge.

The following guidelines are suggested to control Cryptosporidium:

  • Minimise contact between healthy and infected livestock.
  • Take particular care with vulnerable new-born animals to ensure they do not become infected.
  • Compost farmyard manure, aerate slurry and store wastes for as long as is practicable to help kill the parasite.
  • Avoid discharging dirty water into drains and comply with DEFRA's Code of Practice for the Protection of Water.

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