In a campaign of 7 years' duration to control malaria in Netherlands New Guinea, house spraying was combined with mass distributions of chloroquine and pyrimethamine.
In several moderately endemic areas, eradication was practically or almost achieved. Even in a holoendemic region, a point has been reached where eradication seems possible. However, in other areas, where people are of a roving disposition, results of house spraying and drug distribution were disappointing. The number of infections to which a population is exposed before control measures come into operation appears to be of major importance in relation to success or failure of eradication efforts. Aspects of holoendemic malaria, on which a new classification of malaria endemicity is based, are discussed. Changes in the ratio of the species of malaria parasites were not in accordance with expectations, falciparum showing an unexpected resurgence attributed to a more rapid loss of immunity to this species than to vivax. Future policy will be to continue residual spraying and drug distribution, supplemented by the use of medicated salt in problem areas and gradual bonification.
Present address: Laboratory for Microbiology of the State University, Wasseraarseweg 56, Leiden, The Netherlands.