A study of the proportions of swimmers among well controls and children with enterovirus-like illness shedding or not shedding an enterovirus.

CHildren between the ages of less than 1 year and 15 years who visited a pediatric clinic in Madison, Wisconsin, from June 13 through September 1, 1977, were surveyed for the frequency and location of swimming they had done in the two weeks prior to the clinic visit. The study population consisted of 679 well controls, and 296 children with enteroviral-like syndromes. Throat and rectal swab specimens were collected from 241 of the ill patients and from 27 well children. Non-polio enteroviruses were recovered from 119 ill and two well individuals. Other viruses were recovered from an additional 13 ill patients. The majority of viral-like syndromes were respiratory, with or without fever and gastrointestinal symptoms. Exclusive beach swimmers had significantly (p less than 0.0005) increased relative risk (odds ratio estimate 3.41) of enterovirus illness. The highest relative risk (10.63) of enterovirus illness occurred in children less than 4 years old who were exclusive beach swimmers. Swimming in pools exclusively carried no significantly increased risk of enterovirus illness. Children with apparent viral illnesses based on clinical findings, who had no virus isolated, did not differ from well controls in the type of swimming exposure (either beaches or pools) in the two weeks prior to their clinic visit.