Surveillance of enterovirus infections in Bangkok. I. Isolation of enterovirus from faecal specimens of healthy children.

During the period August 1970 through July 1973, about 50 faecal specimens collected each month from healthy pre-school children of lower economic status in Bangkok were studied for virus isolation using primary monkey kidney cells and new born mice. From a total of 1,823 samples, 557 (30.5%) were positive: 86 (4.8%) polioviruses, 77 (4.2%) coxsackieviruses B, 223 (12.2%) echoviruses, and 127 strains (7.0%) of unidentified viruses. Altogether, 45 serotypes of enteric viruses were identified. More than 30 serotypes, including the 3 types of poliovirus, were present each year. Infection rates were higher in males than in females and highest at one year of age, the rates decreasing with progressing age. There was no marked seasonal variation of enterovirus infections in Bangkok. The poliovirus infection index was low from September to January, and the index of polio and non-polio enterovirus infections was highest in April.