Effectiveness of twice a week prophylaxis with atovaquone-proguanil (Malarone®) in long-term travellers to West Africa

Abstract

Background: Current guidelines recommend daily dosing of atovaquone-proguanil (AP), beginning a day before travel to endemic areas and continuing for 7 days after departure. Adherence of long-term travellers to daily malaria chemoprophylaxis tends to be poor, even when residing in highly endemic malaria regions. Evidence from a volunteer challenging study suggests that non-daily, longer intervals dosing of AP provides effective protection against Plasmodium falciparum. This study examines the effectiveness of twice weekly AP prophylaxis in long-term travellers to highly endemic P. falciparum areas in West Africa. Methods: An observational surveillance study aimed to detect prophylactic failures associated with twice weekly AP, during the years 2013-2014, among long-term expatriates in two sites in West Africa. The expatriates were divided according to the malaria prophylaxis regimen taken: AP twice weekly; mefloquine once weekly and a group refusing to take prophylaxis. Malaria events were recorded for each group. The incidence-density of malaria was calculated by dividing malaria events per number of person-months at risk. Results: Among 122 expatriates to West Africa the malaria rates were: 11.7/1000 person-months in the group with no-prophylaxis (n=63); 2.06/1000 person-months in the 40 expatriates taking mefloquine (P=0.006) and no cases of malaria (0/391 person-months, P=0.01) in the twice weekly AP group (n=33). Conclusions: No prophylaxis failures were detected among the group of expatriates taking AP prophylaxis twice weekly compared with 11.7/1000 person-months among the no-prophylaxis group. Twice weekly AP prophylaxis may be an acceptable approach for long-term travellers who are unwilling to adhere to malaria chemoprophylaxis guidelines.