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. 2011 May 2:10:110.
doi: 10.1186/1475-2875-10-110.

The emergence of insecticide resistance in central Mozambique and potential threat to the successful indoor residual spraying malaria control programme

Ana P Abilio  1 , Immo Kleinschmidt, Andrea M Rehman, Nelson Cuamba, Varsha Ramdeen, David S Mthembu, Sarel Coetzer, Rajendra Maharaj, Craig S Wilding, Andrew Steven, Marlize Coleman, Janet Hemingway, Michael Coleman
Affiliations

The emergence of insecticide resistance in central Mozambique and potential threat to the successful indoor residual spraying malaria control programme

Ana P Abilio et al. Malar J. .

Abstract

Background: Malaria vector control by indoor residual spraying was reinitiated in 2006 with DDT in Zambézia province, Mozambique. In 2007, these efforts were strengthened by the President's Malaria Initiative. This manuscript reports on the monitoring and evaluation of this programme as carried out by the Malaria Decision Support Project.

Methods: Mosquitoes were captured daily through a series of 114 window exit traps located at 19 sentinel sites, identified to species and analysed for sporozoites. Anopheles mosquitoes were collected resting indoors and tested for insecticide resistance following the standard WHO protocol. Annual cross sectional household parasite surveys were carried out to monitor the impact of the control programme on prevalence of Plasmodium falciparum in children aged 1 to 15 years.

Results: A total of 3,769 and 2,853 Anopheles gambiae s.l. and Anopheles funestus, respectively, were captured from window exit traps throughout the period. In 2010 resistance to the pyrethroids lambda-cyhalothrin and permethrin and the carbamate, bendiocarb was detected in An. funestus. In 2006, the sporozoite rate in An. gambiae s.s. was 4% and this reduced to 1% over 4 rounds of spraying. The sporozoite rate for An. funestus was also reduced from 2% to 0 by 2008. Of the 437 Anopheles arabiensis identified, none were infectious. Overall prevalence of P. falciparum in the sentinel sites fell from 60% to 32% between October 2006 and October 2008.

Conclusion: Both An. gambiae s.s. and An. funestus were controlled effectively with the DDT-based IRS programme in Zambézia, reducing disease transmission and burden. However, the discovery of pyrethroid resistance in the province and Mozambique's policy change away from DDT to pyrethroids for IRS threatens the gains made here.

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Figures

Figure 1
Figure 1
Map showing the location of sentinel sites in Zambézia province, Mozambique.
Figure 2
Figure 2
An. gambiae s.l. and An. funestus species abundance from all 19 sentinel sites combined. Collections did not occur 09 2007 to 01 2009 due to logistical problems.
Figure 3
Figure 3
Temporal change in prevalence of P. falciparum in children 1 to 15 years of age between 2006 and 2009.
See this image and copyright information in PMC

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