Prophylaxis Failure Against Vivax Malaria in Guyana, South America.

Chloroquine-resistant Plasmodium vivax was originally reported in Papua, New Guinea by Reickman in 1989.1 In the same year, in Colombia, South America, Arias and Corredor2 reported relapses of 11 patients suffering from vivax malaria, following a chloroquine-primaquine regimen. Garavelli and Corti3 suggested chloroquine-resistant Plasmodium vivax may be present in Brazil following these therapeutic relapses. Further therapeutic failures in returned travelers from South America were reported by Moore et al (1994).4 We report vivax malaria in a group of expeditioners visiting Guyana who, whereas compliant with antimalarial chemoprophylaxis, developed clinical malaria, adding evidence to the presence of chloroquine-resistant Plasmodium vivax in South America. Raleigh International is a youth development charity that undertakes environmental and community projects around the world. These are usually in remote locations. Nine expeditions in countries such as Chile, Belize, Zimbabwe, Uganda, and Malaysia are organized annually. A project manager and a medical officer are placed at each site, along with approximately 10 venturers (age 17-25.) Participants are of all nationalities, but, at present, they are predominantly British.