Colonies of three strains of Aëdes aegypti resistant to DDT were obtained from Trinidad, Haiti and Malaya and reared beside a normal colony. From their relative resistance to a series of compounds analogous to DDT, characteristic resistance "spectra" were obtained. The two colonies from the West Indies showed a similar type of resistance, rather different from the (smaller) resistance of the Malay strain. No resistance to methoxychlor or dieldrin was found.
The author reviews the distribution, epidemiology, and treatment of filarial infection due to Brugia malayi, with special reference to Malaya. B. malayi infection in man is confined to the Far East between longitudes 75 degrees E and 140 degrees E and is essentially rural. The chief vectors are Mansonia spp., Anopheles hyrcanus group, A. barbirostris group, and Aëdes togoi. The epidemiological picture is complicated by the fact that B. malayi and other closely related species have now been found in several species of animals. The existence of an animal reservoir of infection might have important implications for filariasis control. As to the treatment of B. malayi infection, diethylcarbamazine has been found to reduce the microfilaria count and to kill the adult worms; the severe febrile reactions of microfilaria carriers to the initial doses of this drug may be reduced by administration of the steroid prednisolone.
During the past decade outbreaks of a severe haemorrhagic disease caused by dengue viruses of multiple types have been reported in the Philippines, Thailand, Malaysia, Viet-Nam and eastern India. In many of these outbreaks chikungunya virus, a group A arbovirus, was simultaneously the cause of similar but probably milder disease. Both these viruses appear to be able to be able to produce classical dengue fever in some individuals and disease with haemorrhagic manifestations in others. Because of the growing public health importance and the progressive spread of this disease a unified review of its clinical and epidemiological features has been needed. This paper presents the history and salient clinical features of mosquito-borne haemorrhagic fever and summarizes recent epidemiological studies and current diagnostic and control methods.