Cryptosporidiosis in England and Wales: prevalence and clinical and epidemiological features. Public Health Laboratory Service Study Group.

In a two year study carried out by 16 public health laboratories in England and Wales 62,421 patients with presumed infective diarrhoea were investigated. Cryptosporidium infection was identified in 2% (1295), ranging from 0.5% to 3.9% among laboratories. The positivity rate for cryptosporidium was highest in 1-4 year olds, and in children cryptosporidium was the second commonest pathogen after campylobacter. Illness was usually limited to abdominal cramps and watery diarrhoea with six motions/24 hours at worst and lasting seven days. Fewer than half the patients reported fever or vomiting. More severe illness with fever, abdominal cramps, vomiting, and watery diarrhoea of frequency greater than five motions in 24 hours was reported by only a tenth of cases but with a significantly increased prevalence in young adult males. One hundred and fifty five patients (12%) probably acquired their infection abroad; 102 (9%) of patients who acquired their infection at home reported drinking raw milk in the month before onset, and 253 (22%) reported close contact with farm animals. Most laboratories experienced sudden infrequent increases in incidence in the community, only one of which was attributed to a recognised outbreak, which occurred in a nursery. Cryptosporidium should be routinely sought by laboratories investigating acute infectious diarrhoea, especially in children; up to a quarter of cases may be directly zoonotic, and the remainder may be due to person to person spread and waterborne infection.