Mapping Insecticide Resistance for Malaria Control in Mali

BackgroundInsecticide-based vector control, indoor residual spraying (IRS), long lasting insecticide-treated nets (LLINs), form the main components of malaria control in Mali. There is, however, a growing concern that insecticide resistance (IR) may impede the effectiveness of these interventions. There is no up-to-date data on the magnitude and the distribution of IR in Mali except for PMI-supported IRS target areas where IR data is collected annually to inform IRS programming. The objective of this study was to investigate the susceptibility level and distribution of An. gambaie s.l to the four classes of insecticides recommenced for malaria vector control in representative central and southern areas in Mali to help mitigate resistance and plan effective vector control interventions in the future.

Materials and MethodsThe standard WHO tube bioassay test was used to determine the susceptibility status of An.gambaie s.l to bendiocarb, deltamethrin, lamdacyhalothrin, DDT, and fenitrothion from November to December 2012. One to five day old non-blood-fed female adults reared from field collected larvae and pupae were used for the test. Thirteen sites were chosen based on the factors that affect level of resistance such as the scale of LLINs distribution, use of IRS, use of insecticides for agriculture and geographic diversity.

Moussa BM CISSE1,2, Josepha TRORE1,2, Seydou Traore1,2, Chitan Keita1, Elie BENKINEZA1,2, Dereje DENGELA2, Bradford LUCAS2,Jules MIHIGO3,4, Aboubacar SADOU1,2, Kristen L GEORGE5, Christen FORNADEL5, Beach RAYMOND3.

1-African Indoor Residual Spraying Mali. Cite du Niger. BP: 34. Bamako-Mali, 2-Abt Associates 4550 Montgomery Ave, Suite 800 N Bethesda, MD 20814, USA, 3-Center Disease Control, Atlanta, USA, 4-President’s Malaria Initiative USAID/Mali, ACI2000; Rue 243, Porte 297- BP 34, Bamako, Mali, 5-President’s Malaria Initiative USAID, Pennsylvania Avenue NW , Washington DC, USA

Conclusion

An. gambaie s.l test results from the study areas depicted a high level of resistance to DDT. Full susceptibility to fenitrothion was recorded in all the test sites. Reduced susceptibility to bendiocarb was noticed in 2 test sites (Kita and Kadiolo districts) out of 13. Kita and Kadiolo districts are known for growing cotton and intensive use of pesticides in cotton cultivation areas. Increased resistance to deltamethrin, and lambdacyhalothrin was detected in all areas where the tests have been conducted. Resistance to DDT and deltamethrin has increased significantly compared with data from WHO-AFRO-Mali (2009). This increase in resistance might be explained by cross resistance between DDT and pyrethroids and wide use of pyrethroids for agriculture and increased coverage of pyrethroid treated nets.

Acknowledgments

We wish to thank all technicians who participated in the field collection of larvae and provided support during the testing. This work was funded by the President’s Malaria Initiative.

www.africairs.netinfo@africairs.net

Results and DiscussionWHO Susceptibility Test Results

DDT Fenitrothion Lamdacyhalothrin and Deltamethrin Bendiocarb

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Mapping of Insecticides Resistance for Malaria Control in Mali, West Africa Moussa BM CISSE1,2, Josepha TRORE1,2, Seydou Traore1, 2, Chitan Keita1, Elie BENKINEZA1, 2, Dereje DENGELA2, Bradford LUCAS 2,Jules MIHIGO3,4, Aboubacar SADOU4, Kristen L GEORGE5, Christen FORNADEL5, Beach RAYMOND3. 1-African Indoor Residual Spraying Mali. Cite du Niger. BP: 34. Bamako-Mali, 2-Abt Associates 4550 Montgomery Ave, Suite 800 N Bethesda, MD 20814, USA, 3-Center Disease Control, Atlanta, USA, 4-President’s Malaria Initiative USAID/Mali, ACI2000 ; Rue 243, Porte 297- BP 34, Bamako, Mali, 5-President’s Malaria Initiative USAID, Pennsylvania Avenue NW , Washington DC, USA

Insecticide based malaria vector control, Indoor Residual Spraying(IRS) and Insecticide Treated Nets (ITNs), form main components of malaria control in Mali. There is, however, a growing concern that insecticide resistance (IR) may impend the effect of these interventions. There is no up-to-date data on the magnitude and the distribution of IR in Mali except for PMI-supported IRS target areas where IR data is collected annually to inform IRS programming. The objective of this study was to investigate the susceptibility level and distribution of An. gambaie s.l to the four classes of insecticides recommenced for malaria vector control in representative central and southern areas in Mali to help mitigate resistance and plan effective vector control interventions in the future.

The standard WHO tube bioassay test was used to determine the susceptibility status of An.gambaie s.l to bendiocarb, deltamethrin, lamdacyhalothrin, DDT, and fenitrothion from November to December 2012. One to five day old non-blood-fed female adults reared from field collected larvae and pupae were used for the test. Thirteen sites were chosen based on the factors that affect level of resistance such as the scale of ITNs distribution, use of IRS, use of insecticides for agriculture and geographic diversity.

Results and Discussion WHO Susceptibility Test Results

An. gambaie s.l test results from the study areas depicted high level of resistance to DDT. Full susceptibility to fenitrothion was recorded in all the test sites. Reduced susceptibility to bendiocarb was noticed in 2 test sites (Kita and Kadiolo districts) out of 13. Kita and Kadiolo districts are known for growing cotton and intensive use of pesticides in cotton cultivation areas. Increased resistance to deltamethrin, and lambdacyhalothrin was detected in all areas where the tests have been conducted. Resistance to DDT and deltamethrin has increased significantly compared with data from WHO-AFRO-Mali (2009). This increase in resistance might be explained by cross resistance between DDT and pyrethroids and wide use of pyrethroids for agriculture and increased coverage of Pyrethroid treated nets.

Conclusion The study revealed An gambaie s.l are resistant to DDT, deltamethrin, and lambdacyhalothrin. Results show reduced resistance to bendiocarb in areas with intensive use of pesticides for agriculture and full susceptibly to fenitrothion. These results highlighted the importance of routine resistance monitoring, indentifying a mechanism of resistance, and the need to study the implication of reduced susceptibility to pyrethroids on the efficacy of ITNs.

Acknowledgments We wish to thank all technicians who participated in the field collection of larvae and provided support during the testing. This work was funded by the President’s Malaria Initiative.

www.africairs.net info@africairs.net

DDT Fenitrothion Lamdacyhalothrin and Deltamethrin Bendiocarb

The study revealed An gambaie s.l are resistant to DDT, deltamethrin, and lambdacyhalothrin. Results show reduced resistance to bendiocarb in areas with intensive use of pesticides for agriculture and full susceptibly to fenitrothion. These results highlighted the importance of routine resistance monitoring, indentifying a mechanism of resistance, and the need to study the implication of reduced susceptibility to pyrethroids on the efficacy of LLINs.