IV. Parasitological Observations on Malaria in Natives and Troops, and on Filariasis in Natives

Abstract

D. Summary 1. Malaria parasitemia rates among natives of the Solomon Islands, New Hebrides and Bismarck Archipelago as determined by malaria survey units in the South Pacific between 1942 and 1944 are presented. They show that malaria is hyperendemic in this area. 2. Plasmodium vivax was the most common species encountered in these surveys. P. falciparum was second in incidence, and P. malariae third. Relative incidences of the three species varied on the different islands. 3. The incidence of splenomegaly among natives varied from 34% to 85% on the different islands, but on most was between 50% and 75%. 4. The incidence of microfilariae of Wuchereria bancrofti among the natives varied from 4% on New Caledonia to 39% on Emirau. The rate was 22% on Guadalcanal and Espiritu Santo, 24% in the Samoan area, and 30% in Fiji. 5. Nocturnal periodicity of microfilariae was noted on Guadalcanal, Espiritu Santo and Emirau. There was no periodicity in Samoa or Fiji. 6. Wuchereria malayi was found in 9% of imported Indo-Chinese laborers on Espiritu Santo, but not among the natives on any of the islands surveyed. 7. In the early part of the South Pacific campaign, the predominant type of malaria among troops was caused by P. falciparum. The falciparum-vivax ratio decreased progressively, so that in the latter part of the occupation vivax malaria was far more common than falciparum. This shift was associated with a marked decrease in the general incidence of malaria. 8. Upon removal of troops of troops from a malarious area, P. vivax rapidly became the predominant cause of malaria.