Remarks

• WHO recommends ITNs that have been prequalified by WHO for deployment in protecting populations at risk of malaria.
• ITNs are most effective where the principal malaria vector(s) bite predominantly at night after people have retired under their nets.
• ITNs can be used both indoors and outdoors, wherever they can be suitably hung (though hanging nets in direct sunlight should be avoided, as sunlight can affect insecticidal activity).

Practical Info The current WHO recommendation for ITNs applies only to those mosquito nets that have been prequalified by WHO and that contain only an insecticide of the pyrethroid class (categorized as ‘pyrethroid-only LLINs’). For ITNs that currently do not have a recommendation, WHO will determine the data requirements for assessing their public health value based on technical advice from the Vector Control Advisory Group (VCAG). As with all insecticide-based interventions, the insecticide resistance profile of the vectors within the area of deployment should be assessed. If pyrethroid-resistance is detected, pyrethroid-PBO nets should be considered for distribution, instead of pyrethroid-only nets (see the following recommendation on pyrethroid-PBO nets). ITNs are generally acceptable to most communities. In many malaria-endemic countries, untreated nets were in use for many years prior to the introduction of ITNs and, even where there is not a long history of their use, they have become familiar tools for preventing mosquito bites. Individuals often appreciate the extra privacy afforded by a net, as well as its effectiveness in controlling other nuisance insects. In very hot climates, ITNs may be less acceptable, as they are perceived to reduce air flow, making it too hot to allow for a comfortable sleep. In areas where mosquito densities are low or where malaria transmission is low, individuals and communities may perceive less benefit to using nets. When deploying ITNs, coverage must be optimized such that both personal and community-level effects are maximized and maintained in endemic settings. Post-distribution monitoring of nets is essential, reporting their durability, usage and coverage. Evaluation of the impact on vectors, such as their abundance, EIR and behaviour, and insecticide resistance status can be used to inform and guide future deployment. Nets should be handled and disposed of appropriately to minimize risk to human and animal health and of environmental contamination. WHO recommends that old nets are not burned in the open air but are buried, preferably in non-permeable soil and away from water sources. Burning may lead to the release of dioxins, which are harmful to human health. The insecticides used on nets are toxic to aquatic organisms and so should not be disposed of in water.