The spread of chloroquine-resistant malaria in Africa. Implications for travelers.

Spreading from 2 countries in 1978 to at least 29 in 1988, chloroquine-resistant Plasmodium falciparum malaria has become a significant concern for travelers to Africa. The spread of chloroquine resistance has been documented by sporadic case reports and by isolated population surveys, which do not always completely reflect the risk of infection for travelers using chloroquine prophylaxis. Surveillance of Peace Corps volunteers in West Africa indicates that as of January 1, 1989, P falciparum malaria resistant to chloroquine prophylaxis had spread as far west as Liberia, with only limited risk in Sierra Leone and to the north and west of Sierra Leone. Monitoring the incidence of malaria in highly exposed expatriates provides early warning of the emergence of drug-resistant P falciparum malaria and can provide data to guide recommendations for travelers.