Respiratory viruses in hospital patients on the Witwatersrand. A 7-year study.

Virological investigations were carried out on 4 151 patients with respiratory disease hospitalized between May 1966 and April 1972. The groups examined were Black and White children and Black miners. Influenza viruses were more common among malnourished Black children and tended to cause more severe disease. This was also true of adenovirus and Herpesvirus hominis type 1 infections. Adenoviruses appear to be secondary invaders, frequently after a measles or influenza attack. A generalized epidemic of adenovirus type 7 occurred in 1967, the longest, coldest and most humid winter during the survey. The season of peak occurrence for respiratory syncytial (RS) virus is autumn, not winter as found elsewhere. The parainfluenza viruses differ from each other, types 1 and 2 being commoner in older children (12--48 months), mainly causing laryngotracheobronchitis (LTB), whereas type 3 is commoner in younger children (0--23 months), mainly causing pneumonia. The miners showed a preponderance of influenza A infections. The miners' origin from remote villages and high turnover rate create a situation where a given strain will persist at a moderate level for long periods, unlike in the general population where an outbreak lasts for only about 6--8 weeks. As opposed to other closed communities, adenovirus infections were rare. The reason for this is obscure.