Malaria in the Republic of the Philippines. A review.

Malaria in the Republic of the Philippines is caused principally by P. falciparum and P. vivax, with the former as predominant species. P. malariae is occasionally reported, while P. ovale is very rare and has been reported only in the island of Palawan. Malaria is widespread in distribution with prevalence varying from one area to the other. In 1970, the malaria morbidity rate was reported to be 77.6 per 100,000 while the mortality rate was 1.8 per 100,000. Case detection activities revealed that, in 1973, the slide parasite rate was 7.2%, the annual parasite index was 6.1% and the annual blood examination rate was 8.4%. The principal vector of malaria in the Philippines is An. minimus flavirostris which breeds in clear, fresh-water streams in foothills and mountain slopes. An. mangyanus and An. maculatus appear to play a secondary role. The vectorial capacity of the former appears to be confined only where conditions are primitive, while the latter is associated with malaria transmission in high altitudes. In the absence of fresh-water streams, the salt-water breeder mosquito, An. litoralis, assumes the vectorial role. The epidemiology of malaria in the Philippines is discussed. Emergence of strains of P. falciparum with diminished sensitivity to the commonly used antimalarial drugs is reported in Palawan and Rizal provinces. The development of malaria control activities in the Philippines are presented. As of 1972, Cagayan Valley, Palawan, Mindoro, Sulu and circumscribed areas in Mindanao are still considered hard-core malarious areas with on-going persistent transmission.