Mosquito net

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Ceiling hung mosquito netting.
Frame hung mosquito netting.
Tent made of mosquito netting.
Window with mosquito netting.

A mosquito net offers protection against mosquitos,[1] flies, and other insects, and thus against diseases such as malaria, dengue fever, yellow fever, and various forms of encephalitis, including the West Nile virus,[2] if used properly and especially if treated with an insecticide, which can double effectiveness. Its fine, see-through, mesh construction stops many insects from biting and disturbing the person using the net. The mesh is fine enough to exclude these insects, but it does not completely impede the flow of air.

Contents

[edit] History

Mosquito netting has a long history. Though use of the term dates from the mid 1700s,[1] use of mosquito nets has been dated to prehistroric times. It is said that Cleopatra, Queen of Egypt, also slept under a mosquito net.[3] Mosquito nets were used during the malaria-plagued construction of the Suez Canal.[3]

[edit] Construction

Mosquito net can be made from cotton, polyethylene, polyester, or nylon.[4] A mesh size of 1.2 mm stops mosquitoes, and smaller, such as 0.6 mm, stops other biting insects such as no-see-ums.[5]

[edit] Usage

Mosquito nets are often used where malaria or other insect-borne diseases are common, especially as a tent-like covering over a bed. For effectiveness, it is important that the netting not have holes or gaps large enough to allow insects to enter. Because an insect can bite a person through the net, the net must not rest directly on the skin.

Mosquito netting can be hung over beds, from the ceiling or a frame, built into tents, or installed in windows and doors. When hung over beds, rectangular nets provide more room for sleeping without the danger of netting contacting skin, at which point mosquitoes may bite through untreated netting.[6]

[edit] Insecticide treated nets

Mosquito nets treated with insecticides—known as insecticide treated nets (ITNs) -- were developed in the 1980s for malaria prevention. Insecticide-treated nets (ITN) are estimated to be twice as effective as untreated nets,[7] and offer greater than 70% protection compared with no net.[8] These nets are dip treated using a synthetic pyrethroid insecticide such as deltamethrin or permethrin which will double the protection over a non-treated net by killing and repelling mosquitoes.

The distribution of mosquito nets impregnated with insecticides such as permethrin or deltamethrin has been shown to be an extremely effective method of malaria prevention, and it is also one of the most cost-effective methods of prevention. These nets can often be obtained for around $2.50–$3.50 (2–3 euros) from the United Nations, the World Health Organization (WHO), and others. ITNs have been shown to be the most cost-effective prevention method against malaria and are part of WHO’s Millennium Development Goals (MDGs).

For maximum effectiveness, the nets should be re-impregnated with insecticide every six months. This process poses a significant logistical problem in rural areas. New technologies like Olyset or DawaPlus allow for production of long-lasting insecticidal mosquito nets (LLINs), which release insecticide for approximately 5 years,[9] and cost about US$5.50. ITNs protect people sleeping under the net and simultaneously kill mosquitoes that contact the net. Some protection is also provided to others by this method, including people sleeping in the same room but not under the net.

Unfortunately, standard ITNs must be replaced or re-treated with insecticide after six washes and, therefore, are not seen as a convenient, effective long-term solution to the malaria problem.[10] As a result, the mosquito netting and pesticide industries developed so-called long-lasting insecticidal mosquito nets (LLINs), which also use pyrethroid insecticides. There are two types of LLINs, one which is polyester netting and the insecticide is bound to the external surface of the netting fiber using a resin and another which incorporates the insecticide into a polyethylene fiber which then releases the insecticide slowly over 5 years. Both types can be washed at least 20 times but physical durability will vary, a survey carried out in Tanzania concluded that effective life of polyester nets was 2 to 3 years (Erlanger et al., 2004, Med Vet Entomol 18: 153-160), with polyethylene LLINs there is data to support > 5 years life with trials in showing nets which were still effective after 7 years (Tami, A et al. Malaria Journal 2004, 3:19). When calculating the cost of LLINs for large scale malaria prevention campaigns the cost should be divided by the number of years of expected life, hence a slightly more expensive net may be cheaper over time. In addition the logistical costs of replacing nets should be added to the calculation.

[edit] Scientific trials of ITNs

A review of 22 randomized controlled trials of ITNs[11] found (for Plasmodium falciparum malaria) that ITNs can reduce deaths in children by one fifth and episodes of malaria by half.

More specifically, in areas of stable malaria "ITNs reduced the incidence of uncomplicated malarial episodes by 50% compared to no nets, and 39% compared to untreated nets" and in areas of unstable malaria "by 62% compared to no nets and 43% compared to untreated nets". As such the review calculated that for every 1000 children protected by ITNs, 5.5 lives would be saved each year.

[edit] Alternatives

Mosquito nets do reduce air flow to an extent and sleeping under a net is hotter than sleeping without one, which can be uncomfortable in tropical areas without air-conditioning.[citation needed]

One alternative for reducing mosquito bites is to use a fan to increase air flow, as mosquitoes prefer still air; however, this is far less effective and mosquito netting is preferable in areas with insect-borne diseases.[citation needed]

Another alternative is to apply an insect repellent to the skin; this also may be less effective (reducing rather than eliminating bites), more expensive, and may pose health risks with long-term use.

[edit] See also

[edit] References

  1. ^ a b Oxford English Dictionary (draft ed.). Oxford University Press. 2009. 
  2. ^ "All Mosquito Netting Info". http://www.mosquito-netting.com/. Retrieved 2009-10-27. 
  3. ^ a b "History of Malaria Control". http://www.malariasite.com/malaria/history_control.htm. Retrieved 2009-10-27. 
  4. ^ "World Health Organization: Annex VII : Procedure for Treating Mosquito Nets and curtains". http://searo.who.int/en/Section10/Section332/Section554_2554.htm. Retrieved 2009-10-27. 
  5. ^ "Mosquito Netting Criteria". http://www.mosquito-netting.com/mosquito-netting.html. Retrieved 2009-10-27. 
  6. ^ "Travel Health Help: Mosquito Nets". http://www.travelhealthhelp.com/mosquito-nets.html. Retrieved 2009-10-27. 
  7. ^ Hull, Kevin. (2006) "Malaria: Fever Wars". PBS Documentary
  8. ^ Bachou H, Tylleskär T, Kaddu-Mulindwa DH, Tumwine JK (2006). "Bacteraemia among severely malnourished children infected and uninfected with the human immunodeficiency virus-1 in Kampala, Uganda". BMC Infect. Dis. 6: 160. doi:10.1186/1471-2334-6-160. PMID 17090299. 
  9. ^ New Mosquito Nets Could Help Fight Malaria in Africa
  10. ^ "Insecticide-Treated Mosquito Nets," WHO, p.5
  11. ^ Lengeler C. (2004) Insecticide-treated bed nets and curtains for preventing malaria. The Cochrane Database of Systematic Reviews. Issue 2. [1]

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Mosquito_net"