Studies on a West African strain of plasmodium falciparum The efficacy of paludrine (proguanil) as a prophylactic agent

The investigations recorded relate to a strain of P. falciparum obtained in November, 1947, from a native of Lagos, Nigeria, West Africa. 2. Twenty non-immune individuals (four groups of five in each group) were subjected to repeated infections with this strain of parasite over a period of 6 weeks. During this time Group I received paludrine mg. 100 daily; Group II, mg. 50 daily; Group III, mg. 100 twice weekly; and Group IV, mg. 300 once weekly. None of the members of these four groups developed an overt malarial attack during the period of drug administration or subsequently. 3. Two persons taking respectively quinine hydrochloride grain 5 and grain 10 daily were infected in a similar manner as those in Groups I to IV. The infection was effectively suppressed in both cases whilst the drug was being taken, but both developed overt attacks of malaria 7 and 12 days respectively after it was discontinued. 4. Although paludrine acted as a true causal prophylactic of the Lagos strain of P. falciparum in each of the regimes under trial, it is considered that non-immune persons residing in or visiting West Africa should be advised to take not less than mg. 100 of the drug daily for the prophylaxis of malaria. For semi-immune subjects, such as native labour forces and locally recruited Government employees, a weekly dose of paludrine mg. 300 is recommended.