Drug resistant malaria on the Thai-Myanmar and Thai-Cambodian borders.

We describe the changing epidemiology of drug resistant malaria in Thailand over the past decade. Factors determining the characteristic patterns of the development and spread of resistance to anti-malarial drugs on the Thai-Cambodian border and the Thai-Myanmar border are explored, namely, population dynamics, drug usage and malaria control measures. The introduction of artesunate-mefloquine combination in selected areas along the two borders in 1995 is believed to be one of the multiple factors responsible for stabilizing the multidrug resistance problems in Thailand today. Other control measures and inter-governmental co-operation must continue to be strengthened in order to limit the spread of drug resistance malaria in the Southeast Asian region.

Proguanil/sulfamethoxazole malaria chemoprophy-laxis on the Thai-Cambodian border.

383 Thai soldiers on the Thai-Cambodian border were entered into a randomized malaria chemoprophylactic trial. Proguanil (200 mg/day) combined with sulfamethoxazole (1000 or 1500 mg/day) were compared to a standard combination of weekly pyrimethamine/dapsone (Maloprim). Men receiving proguanil/sulfamethoxazole had a significantly lower malaria attack rate than those taking pyrimethamine/dapsone. This was true of both the first five-week phase in which 1000 mg of sulfamethoxazole was used (0.11 vs 0.26; p less than 0.001) and in the second ten weeks in which 1500 mg of sulfamethoxazole was used (0.13 vs 0.30; p less than 0.001). Combined relative efficacy indicated that proguanil/sulfamethoxazole was better than pyrimethamine/dapsone by 64% for Plasmodium vivax and by 38% for P. falciparum. Unenforced compliance as measured by returned pills was greater than 86% in both groups. No serious drug side-effects were observed. Proguanil/sulfamethoxazole may represent a useful chemoprophylactic option in areas of multiple drug-resistant malaria.

Malaria in displaced persons along the Thai-Burmese border.

Malaria epidemiology in displaced Karen ethnic children along the Thai-Burmese (Myanmar) border was observed for 3 years. An active screening process in connection with malaria chemoprophylaxis trials showed a decrease in malaria prevalence over time in children not receiving chemoprophylaxis. The number of malaria cases detected at a primary health care clinic in the same area remained stable.

Malaria prophylaxis with doxycycline in soldiers deployed to the Thai-Kampuchean border.

A battalion of Royal Thai Marine militia was assigned to take either 50 mg or 100 mg of doxycycline daily or pyrimethamine/dapsone weekly for malaria prophylaxis on the Thai-Kampuchean border for a 17 week period. Attack rates for the groups expressed as cases/100 men were 34 for 50 mg doxycycline, 18 for 100 mg doxycycline, and 52 for pyrimethamine/dapsone. The relative efficacy of the two doxycycline regimens compared to Maloprim were 1.6 and 1.4. Compliance with the daily drug nearly equalled that of the weekly regimen. This suggests that 100 mg of doxycycline daily can be effectively used for malaria prophylaxis by soldiers under operational conditions on the Thai-Kampuchean border.