Failure of Chloroquine Treatment to Prevent Malaria in Americans in West Africa

To the Editor.— Since chloroquineresistant falciparum (CRPF) malaria was first reported in Africa in 1978, 1 it has spread steadily westward and is now well established in coastal Benin. 2 Confirmed reports of CRPF malaria west of Benin are limited to a single case in Ghana 3 and reports of decreased sensitivity to chloroquine therapy in patientswith Plasmodium falciparum from Gambia 4 and Senegal. 5 A study of Togolese children in 1985 showed that administration of 10 mg/kg of chloroquine base was highly effective in eliminating parasites from the blood. 6 We now report five cases of P falciparum among expatriates in Togo who had taken regular chloroquine prophylaxis (300 mg of base per week). Study.— The five patients were American Peace Corps volunteers (PCVs) between the ages of 20 and 40 years who had been living in Togo for more than six months. None had traveled to