Pharyngoconjunctival fever caused by adenovirus type 4: report of a swimming pool-related outbreak with recovery of virus from pool water.

During the summer of 1977, an outbreak of pharyngoconjunctival fever (PCF) occurred at a private recreational facility in Georgia. A total of 72 cases of PCF was identified. Adenovirus type 4 (AV-4) was recovered from conjunctival or pharyngeal swab specimens from 20 of 26 persons in the group of cases tested. AV-4 was also recovered, for the first time reported in the literature, from two concentrated samples of water obtained from the swimming pool at the facility on different dates. All persons affected had had direct or indirect contact with the pool. A linear relation between the amount of time spent in the water and the attack rate was demonstrated (r = 0.929, P less than 0.01). Investigation showed that inadequate amounts of chlorine had been added to the pool water. Frequently, levels of free chlorine were below the recommended level of 0.4 mg/liter. Breakpoint chlorination and closing of the pool for the summer stopped the spread of PCF.