Country-level operational implementation of the Global Plan for Insecticide Resistance Management

Abstract

Malaria control is reliant on the use of long-lasting pyrethroidimpregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs. M alaria control activities in Africa have been scaled up during the last decade. Disease control is predominantly dependent on the distribution and use of pyrethroid-impregnated long lasting insecticide-treated nets (LLINs) and/or indoor residual spraying (IRS) of insecticides. The choice of insecticides for IRS is currently limited to four classes with only two modes of action. One of these insecticide classes, pyrethroids, is also the only class recommended for use by the World Health Organization (WHO) on LLINs. The recent rapid selection and spread of pyrethroid resistance in malaria vectors has stimulated the WHO to develop a Global Plan for Insecticide Resistance Management (1), encouraging countries to plan and implement insecticide resistance management strategies and to underpin these strategies with proper, timely entomological resistance monitoring and effective data management. This must be implemented in the short term at the same time mediumto long-term efforts are made to expand the available insecticide choice (2). To be effective, resistance management plans need to be closely aligned with local evidence supported by an effective monitoring system.Here we detail how this process has been un...

Pyrethroid Insecticide Resistance <i>kdr</i> Gene in the House Fly, <i>Musca domestica</i> (Diptera: Muscidae), in the United Arab Emirates

“…Accordingly, the pyrethroid insecticide list used for the control of house flies in the UAE should be reevaluated in order to reduce the frequency of the kdr resistance allele in the fly population. In addition, a country-wide operational implementation of a global plan for insecticide resistance management is also warranted [14].…”

Averting a malaria disaster: will insecticide resistance derail malaria control?

“…Here the guidance from WHO is clear, but so far, very few African countries have well developed resistance management plans for indoor residual spraying, 18,19 and for some countries, faced with resistance to all available chemistries, the advice is of theoretical rather than practical relevance. In any case, all insecticide resistance management strategies need the introduction of methods that are more expensive than current interventions.…”

Identification, Validation, and Application of Molecular Diagnostics for Insecticide Resistance in Malaria Vectors

“…Despite major advances in identification and characterization of resistance mechanisms [17, 21, 23, 33] and the availability of resistance DNA diagnostics [17, 33, 53], positive impacts on disease control programmes to date have primarily been limited to retrospective analyses of changes in insecticide application [54, 55]. A change toward prospective analyses which directly guide management strategies is urgently required; this will need geographically tailored data not only on the presence of resistance mechanisms in Anopheles populations, but on their quantitative predictive value for phenotypic resistance.…”