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

Abstract

BackgroundMalaria 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.MethodsMosquitoes 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.ResultsA 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.ConclusionBoth 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.

A New Long-Lasting Indoor Residual Formulation of the Organophosphate Insecticide Pirimiphos Methyl for Prolonged Control of Pyrethroid-Resistant Mosquitoes: An Experimental Hut Trial in Benin

“…Pyrethroid resistant Anophelines are now present in all African countries, and the frequency of resistance is increasing due to selection pressure from LLINs and pyrethroid IRS [12]–[17]. LLINs can still provide personal protection particularly when the netting is intact [40].…”

“…Microencapsulation of pyrethroids and organophosphate insecticides is both feasible and economic and can extend the residual life of insecticides when applied to cement or mud plastered rooms [9]–[11]. With the alarming increase in pyrethroid resistance reported from many endemic African countries [12]–[17], alternative insecticides from non-pyrethroid classes require urgent development, evaluation, approval and registration.…”

Eave Screening and Push-Pull Tactics to Reduce House Entry by Vectors of Malaria

“…5,6 Recent reports confirming the rapid spread of insecticide resistance underline the need for alternative approaches in addition to insecticide-based methods. [7][8][9][10][11][12] In this study, we aimed to quantify the effects of eave screening in combination with a push-pull system that interferes with mosquito host-seeking behavior through the simultaneous release of repellent volatiles from the house eaves to "push" mosquitoes away from the peridomestic space and attractive volatiles released from an odor-baited trap to "pull" mosquitoes toward this alternative, pseudohost and remove them from the environment. Push-pull is a term originally adopted in the context of agricultural pest management.…”

Modelling the spatial spread of a homing endonuclease gene in a mosquito population

“…There is also worrying evidence of the spread of resistance in both the pathogen and the vector (White ; Abilio et al . ; Chanda et al . ).…”