71 Physical and chemical house entry barriers to enhance odour-baited trapping for malaria control
AbstractBackground: Odour-baited mosquito trapping is a promising new malaria intervention that lures, traps and kills mosquitoes. However, mosquitoes still bypass the trapping system and enter easily accessible African households through the open eaves. In this study, house screening and a spatial repellent were used as a physical and chemical house entry barrier to determine whether these interventions can protect people from malaria mosquitoes by decreasing mosquito house entry and simultaneously increasing odourbaited trapping efficacy. Methods: In an experimental greenhouse in Kenya, two semi-field experiments were conducted. In the first experiment, three physical house adjustment interventions were tested against using no intervention: house screening (block); odour-baited trapping (pull) and both interventions (block-pull). In the second experiment, three chemical interventions were tested against using no intervention: a cotton band around the eaves impregnated with the spatial mosquito repellant Delta-undecalactone (push); odourbaited trapping (pull) and both interventions (push-pull). The effects of interventions were evaluated by comparing mean trap catches of the odour-baited trap outside, and mean mosquito house entry. Results: In the first experiment (block-pull), the chance of a mosquito getting caught by an odour-baited trap more than doubled (OR=2.163) when complementing odour-baited trapping with house screening (P<0,001). All interventions significantly reduced mosquito house entry (p<0,001), with the strongest protective effect for the combined intervention of house screening and odour-baited trapping (OR=0.10). The interventions of the second experiment did not have a significant effect on odour-baited trap catches (p=0.584), nor mosquito house entry (p>0.172). Discussion: This study shows that house screening could be a valuable addition to odourbaited mosquito trapping for malaria control and confirmed the strong effect of house screening on mosquito house entry. In contrast to other studies, a chemical barrier of Delta-undecalactone did not improve the protection against malaria mosquitoes. However, push-pull strategies might still be a viable alternative to house screening, since the absence of an effect might have been caused by an interaction of the intervention with the experimental environment.
WHO. World malaria report. 2012 [cited September 24 2013.
Takken, W. and B.G. Knols, Malaria vector control: current and future strategies. Trends in parasitology, 2009. 25(3): p. 101-104.
Control, m.C.G.o.V., A research agenda for malaria eradication: vector control. PLoS medicine, 2011. 8(1): p. e1000401.
Okumu, F.O., et al., Development and field evaluation of a synthetic mosquito lure that is more attractive than humans. PloS one, 2010. 5(1): p. e8951.
Hiscox, A., et al., The SolarMal Project: innovative mosquito trapping technology for malaria control. Malaria J, 2012. 11: p. O45.
Mukabana, W.R., et al., A novel synthetic odorant blend for trapping of malaria and other African mosquito species. Journal of chemical ecology, 2012. 38(3): p. 235-244.
Jawara, M., et al., Optimizing odor-baited trap methods for collecting mosquitoes during the malaria season in The Gambia. PLoS One, 2009. 4(12): p. e8167.
Lindsay, S., et al., Changes in house design reduce exposure to malaria mosquitoes. Tropical Medicine & International Health, 2003. 8(6): p. 512-517.
Lwetoijera, D.W., et al., A need for better housing to further reduce indoor malaria transmission in areas with high bed net coverage. Parasit Vectors, 2013. 6: p. 57.
Kirby, M.J., et al., Effect of two different house screening interventions on exposure to malaria vectors and on anaemia in children in The Gambia: a randomised controlled trial. The Lancet, 2009. 374(9694): p. 998-1009.
Knols, B.G., et al., MalariaSphere: A greenhouse-enclosed simulation of a natural Anopheles gambiae (Diptera: Culicidae) ecosystem in western Kenya. Malaria journal, 2002. 1(1): p. 19.
Mboera, L., et al., Short report: Influence of centers for disease control light trap position, relative to a humanbaited bed net, on catches of Anopheles gambiae and Culex quinquefasciatus in Tanzania. The American journal of tropical medicine and hygiene, 1998. 59(4): p. 595-596.
Howell, D., Statistical methods for psychology. 2012: Cengage Learning.
Menger, D.J., et al., A push-pull system to prevent house entry of malaria mosquitoes. Malaria journal, 2014. 13.
Murlis, J., J.S. Elkinton, and R.T. Carde, Odor plumes and how insects use them. Annual review of entomology, 1992. 37(1): p. 505-532.
Murlis, J. and C. Jones, Fine-scale structure of odour plumes in relation to insect orientation to distant pheromone and other attractant sources. Physiological Entomology, 1981. 6(1): p. 71-86.
Stanczyk, N.M., et al., Aedes aegypti mosquitoes exhibit decreased repellency by DEET following previous exposure. PloS one, 2013. 8(2): p. e54438.
Okumu, F.O., et al., Potential benefits, limitations and target product-profiles of odor-baited mosquito traps for malaria control in Africa. PLoS One, 2010. 5(7): p. e11573.
Smallegange, R.C., et al., Sugar-fermenting yeast as an organic source of carbon dioxide to attract the malaria mosquito Anopheles gambiae. Malar J, 2010. 9(292): p. 10.1186.
Verhulst, N.O., et al., Composition of human skin microbiota affects attractiveness to malaria mosquitoes. PloS one, 2011. 6(12): p. e28991.
UNAID. Delivering results toward ending AIDS, Tuberculosis and Malaria in Africa. African Union accountability report on Africa–G8 partnership commitments 2013. 2013 [cited 2013 December 4, 2013].
Qiu, Y.T., et al., Attractiveness of MM-X traps baited with human or synthetic odor to mosquitoes (Diptera: Culicidae) in The Gambia. Journal of medical entomology, 2007. 44(6): p. 970.
Pates, H. and C. Curtis, Mosquito behavior and vector control. Annu. Rev. Entomol., 2005. 50: p. 53-70.