Mosquito nets offer essential protection against mosquitoes, flies and other insects, especially interritories where malaria, Dengue fever or West Nile virus are spread. It stops many insects from biting and disturbing the person, but allows air to flow freely.
Mosquito nets could be made from different materials, come in different sizes and forms, and could have different hole sizes.
Polyamide (nylon) and polyester (terylene) nets are the most common net material our days, having very high strengths, low weight and high resistance to humid conditions. Cotton was widely used for making mosquito nets before the synthetic materials were invented, but it has lower tear strength and low resistance to damp or mould and is now rarely used.
A mesh size of 1.2 mm x 1.2 mm is common and recommended. The mosquito net mesh size recommended for effective malaria protection is of 120-200 mesh/square inch. Hole size impacts the amount of air coming through the mesh – larger ones let more air in but also more insects could get through while smaller holes prevent almost all insects from reaching a sleeping person, but makes it hotter to sleep inside such mesh. Insects can bite through the net itself, so it must not contact directly with the skin.
Some mosquito nets are treated with insecticides and are called Insecticide Treated Nets (ITNs) – they kill and repel mosquitoes. Several pyrethroid insecticides are usually used for net impregnation – Permethrin and Deltamethrin. Permethrin is a naturally found insecticide with an excellent safety record and has been used for decades. A net treated with Permethrin will need to be treated every 6 months while in use. Permethrin is sensitive to sunlight and washings, so the net has to be stored in a dark, shady place.
Trials of ITNs in the 1980s and 1990s showed that they reduced deaths in young children in Africa by an average of 20% so World Health Organization (WHO) is promoting the use of ITNs throughout the malaria infested regions worldwide, especially poor countries in Africa.