Isolation of apparently wild strains of poliovirus type 1 from sewage in the Ottawa area.

In the first 4 months of 1974, 140 gauze pad samples of sewage collected in the Ottawa area were analysed by the BS-C-1 cell system for the presence of viruses pathogenic for humans. Viruses were isolated from 111 (79%) of the samples. Of the 72 (65%) isolates identified by serology and electron microscopic examination, 56 (78%) were reoviruses and 16 (22%), enteroviruses. The enterovirus isolates included one coxsackievirus B4, one vaccine strain of poliovirus type 3, nine vaccine strains of poliovirus type 1 and five strains of poliovirus type 1 that proved by serodifferentiation and temperature marker tests to be different from vaccine strains. The fact that these strains were present in the community sewage in readily detectable concentrations at a time when immunity against polioviruses is declining in such communities is a cause for concern.