Epidemiology of malaria in displaced Khmers on the Thai-Kampuchean border

Malaria epidemiology from 1983 to 1985 in displaced Khmers living in camps on the Thai-Kampuchean border was studied for planning and evaluation of control measures. The annual parasite incidence per 1000 people fell from 359 in 1983 and 350 in 1984 to 116 in 1985. Incidence varied by camp according to the suitability of the habitat for the vectors. Camps with high incidence had a higher ratio of Plasmodium falciparum to P. vivax, a higher mortality rate, especially in young children and sometimes pregnant women, but a lower case fatality rate than camps with low incidence. Transmission occurred year round, but peaked in the rainy season in 1983 and 1984. In 1985 there was a steady decline in incidence, largely owing to evacuation of many camps away from forested areas. Mortality rates per 100,000 people were 62, 77 and 28 and case fatality rates 0.41, 0.31 and 0.42% in 1983, 1984 and 1985 respectively. The case fatality rate for cerebral malaria was 21 to 26%. Epidemiological information has been more useful for planning than for evaluating control measures.