Cryptosporidium outbreak in Lancashire

7 April 2000

Recent News Stories: Key Points

1. Cryptosporidium outbreak in Lancashire

There has been some media interest in an outbreak of cryptosporidium which occurred in Lancashire in March. Between 4th and 28th March, 45 cases of cryptosporidium were reported in an area served by a single mains water supply in or around the town of Clitheroe.

Several water specimens were taken from the water supply between 16-20 March and were tested, and were found to contain cryptosporidium oocysts. As a result, on 21st March local residents were advised to boil their water.

However, the number of new cases of human infection reported began to decline from mid-March, and new specimens taken from the water supply on 26-27 March were all negative. It is therefore likely that the water supply is now clear and that the risk of infection has passed. The advice to boil water was lifted on the evening of 27 March.

It is possible that further cases may occur amongst people who were infected during March, as the incubation period can be as much as 2 weeks.

Tests carried out by the PHLS indicated that the cryptosporidium organism in the water is of a type which can be found in animals. Local investigations have shown that a spring which feeds a local reservoir is in an animal grazing area. Investigations are continuing locally, and further enquiries about the outbreak should be directed to the local authorities.

For most people cryptosporidium infection, although unpleasant, is not a dangerous illness. Indeed, it can be mild or have no symptoms at all. Where symptoms occur they usually include diarrhoea and vomiting. The infection can be more serious in people who are immunocompromised as these patients can find it difficult to clear the infection from their system; that is why immunocompromised patients are advised always to boil their drinking water.

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Last reviewed: 26 November 2008