Foot and Mouth Disease and Cryptosporidiosis
During 2001, a large outbreak of foot and mouth disease occurred in the United Kingdom, during which approximately 2,030 confirmed cases of the disease were reported, >6 million animals were slaughtered, and strict restrictions on access to the countryside were imposed. We report a dramatic decline in the reported incidence of human cryptosporidiosis in northwest England during weeks 13-38 in 2001, compared with the previous 11 years. This decline coincided with the period of foot and mouth restrictions. No similar reduction occurred in the other 26 weeks of the year. We also noted a substantial decline in the proportion of human infections caused by the bovine strain (genotype 2) of Cryptosporidium parvum during weeks 13-38 in that year but not during the other weeks.

Cryptosporidiosis is an acute diarrheal disease caused by a protozoan parasite Cryptosporidium parvum. Although the disease is self-limiting in most instances, in certain immunocompromised patients the infection can be very severe and potentially fatal. This disease is now the most common parasitic cause of human diarrheal disease in the United Kingdom; over the last 10 years, the northwest region of England has regularly reported more cases than any other region in the country. Cryptosporidiosis was originally thought to be a zoonosis, but epidemiologic studies and the description of two C. parvum genotypes, one of which was only found in humans (genotype 1 or H), has highlighted the importance of person-to-person transmission. Nevertheless, zoonotic transmission is still an important route of infection, though the proportion of human Cryptosporidium infections originating from animals is still unknown.

During 2001, a major outbreak of foot and mouth disease occurred in the United Kingdom. Coincident with this outbreak, we noted a dramatic decline in reports of Cryptosporidium infection in the northwest region. We describe the change in epidemiology of reported cryptosporidiosis during that year and discuss the hypothesis that this reduction may have resulted from public health measures introduced to control the foot and mouth disease epidemic.