The epidemiology of pandemic A2 influenza in the Netherlands, 1957-58.

The virus of pandemic A2 influenza was introduced into the Netherlands by ship and aeroplane from Indonesia and possibly also from the Near East, causing an epidemic of 10 months' duration. The disease spread from two probably independent foci: Bussum and Rotterdam. Three special population groups were attacked first: 70 Ambonesian camps, Army units and the mining district. The main communitywide outbreak started in September 1957 and subsided in November, but cases continued to occur until April 1958 and there was a recrudescence of the disease in January and February 1958. Morbidity was highest among children and adolescents. The mortality rate amounted to about 1 in 3700 inhabitants.