Research
The importance of considering community-level effects when selecting insecticidal malaria vector products
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* Corresponding author: Gerry F Killeen gkilleen@ihi.or.tz
1 Ifakara Health Institute, Biomedical & Environmental Thematic Group, PO Box 53, Ifakara, Morogoro, United Republic of Tanzania
2 Liverpool School of Tropical Medicine, Vector Group, Pembroke Place, Liverpool L3 5QA, UK
3 London School of Hygiene and Tropical Medicine, Disease Control and Vector Biology Unit, Keppel Street, WCIE 7HT, London UK
4 Centre de Recherche Entomologique de Cotonou (CREC), Laboratoire Nationale, Ministère de la Santé, Cotonou 06 BP 2604, Benin
5 Institute of Tropical Medicine Antwerp, Department of Parasitology, Nationalestraat 155, B-2000 Antwerpen, Belgium
6 Department of Biomedical Sciences, Faculty of Pharmaceutical, Veterinary and Biomedical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium
7 Public Health Division, Nigerian Institute of Medical Research, Yaba, Lagos
8 Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), BP. 288, Yaoundé, Cameroun
9 Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O.Box 2701 Douala, Cameroon
10 Institut de Recherche en Sciences de la Santé (IRSS)/Centre Muraz (CM), 01 BP 390, Bobo-Dioulasso, Burkina Faso
11 Institut de Recherche pour le Développement (IRD), Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), UM1-CNRS 5290-IRD 224, Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
Parasites & Vectors 2011, 4:160 doi:10.1186/1756-3305-4-160
Published: 12 August 2011Abstract
Background
Insecticide treatment of nets, curtains or walls and ceilings of houses represent the primary means for malaria prevention worldwide. Direct personal protection of individuals and households arises from deterrent and insecticidal activities which divert or kill mosquitoes before they can feed. However, at high coverage, community-level reductions of mosquito density and survival prevent more transmission exposure than the personal protection acquired by using a net or living in a sprayed house.
Methods
A process-explicit simulation of malaria transmission was applied to results of 4 recent Phase II experimental hut trials comparing a new mosaic long-lasting insecticidal net (LLIN) which combines deltamethrin and piperonyl butoxide with another LLIN product by the same manufacturer relying on deltamethrin alone.
Results
Direct estimates of mean personal protection against insecticide-resistant vectors in Vietnam, Cameroon, Burkina Faso and Benin revealed no clear advantage for combination LLINs over deltamethrin-only LLINs (P = 0.973) unless both types of nets were extensively washed (Relative mean entomologic inoculation rate (EIR) ± standard error of the mean (SEM) for users of combination nets compared to users of deltamethrin only nets = 0.853 ± 0.056, P = 0.008). However, simulations of impact at high coverage (80% use) predicted consistently better impact for the combination net across all four sites (Relative mean EIR ± SEM in communities with combination nets, compared with those using deltamethrin only nets = 0.613 ± 0.076, P < 0.001), regardless of whether the nets were washed or not (P = 0.467). Nevertheless, the degree of advantage obtained with the combination varied substantially between sites and their associated resistant vector populations.
Conclusion
Process-explicit simulations of community-level protection, parameterized using locally-relevant experimental hut studies, should be explicitly considered when choosing vector control products for large-scale epidemiological trials or public health programme procurement, particularly as growing insecticide resistance necessitates the use of multiple active ingredients.