Mefloquine chemoprophylaxis of soldiers on the Thai-Cambodian border.

Chemoprophylaxis of malaria on the Thai-Cambodian border is difficult due to the high level of drug resistance. Thirteen separate companies of Royal Thai Marine Militia were placed on 250 mg weekly mefloquine chemoprophylaxis from August 1989 to January 1990. A mean number of 722 soldiers received two or more doses of mefloquine per month for the five month study. The medication was well tolerated and compliance averaged 91%. Substantial numbers of prophylaxis breakthroughs were seen which resulted in 3.2 cases of malaria/100 man-months. Sixty-eight falciparum malaria cases were documented in men who had taken at least two mefloquine doses in the previous four weeks. No serious neuropsychiatric reactions occurred. Mefloquine chemoprophylaxis failures exist on the Thai-Cambodian border and are one sign of the spread of mefloquine resistance.

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 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.