Malaria Incidence Among Oil/Gas Workers After Three Years of Indoor Residual Spraying (IRS) and two of Improved Case Management on Bioko Island, Equatorial Guinea (EG)

Abstract

Abstract The Bioko Island Malaria Control Project (BIMCP) is a collaborative effort of Marathon Oil, Atlantic Methanol (AMPCO) and partners, the government of Equatorial Guinea (EG), Medical Care Development International and other non-profit partners, and academic institutions. Its aim is to reduce malaria transmission and morbidity and mortality due to malaria in oil workers and in the general population though the use of indoor residual spraying (IRS) and other control measures. Methods: The BIMCP conducted five rounds of IRS between 2004 and 2006 on Bioko Island, Equatorial Guinea. It introduced artemisinin-based combination therapy in 2005 as first line treatment for uncomplicated malaria in health facilities. The BIMCP regularly monitors the mosquito population, the prevalence of malaria parasitemia, malaria incidence, and all-cause mortality in the human population. The BIMCP also monitors malaria incidence in three categories of AMPCO workers. A malaria case was defined as a worker with fever and parasitemia (according to a Rapid Diagnostic Test). Denominators consisted of the number of worker-hours of exposure. Results, Observations, and Conclusions: Malaria incidence among AMPCO's indigenous (EG) workers (particularly those residing in housing areas sprayed by the BIMCP IRS program) declined significantly from 8.23 cases/200,000 man-hours in 2003 to 3.07 in 2006. The corresponding decline in malaria incidence among AMPCO's non-western expatriate workers was from 2.9 to 0.92 for the same interval (overall p<0.00001). The BIMCP also was successful in reducing malaria transmission in the community (parasitemia in children). Significance: The BIMCP diminished the economic burden of malaria for AMPCO workers and their families, and promoted family and community well-being, as well as diminishing the impact of malaria on worker productivity. Marathon Oil, AMPCO, and the NGO and academic partners used BIMCP to strengthen the capacity of the local health system to contain any future resurgence of malaria. The elements required for a resurgence - the presence of malaria vectors, a persistent human reservoir of malaria infection, and susceptible individuals - are still present, albeit at significantly reduced levels relative to the pre-BIMCP period. This successful experience is being scaled up to the rest of EG with additional funding from other sources.