The protozoan that causes malaria (Plasmodium) is transmitted to humans by mosquitoes. Malaria prevention involves breaking contact between humans and mosquitoes so that this transmission cannot take place. One method of breaking contact is to kill the mosquitoes. This can be achieved by using a method called indoor residual spraying, which involves spraying the interior of houses with insecticide. A second, more practical, method, and now the most widely used in endemic malarial areas, is to provide people with bed nets that have been treated with insecticide. The netting itself creates a physical barrier to mosquitoes while people are sleeping, and the insecticide treatment creates a chemical barrier, killing mosquitoes or repelling them.
The more people that use insecticide-treated nets (ITNs) in a community, the greater the collective protection, or "spill-over effect", that is achieved. This benefit to the whole community, even to those not using bed nets, arises for two reasons. First, since ITNs kill mosquitoes, the more ITNs that are in use, the more mosquitoes will be killed, reducing the numbers that can transmit the malaria parasite. Secondly, since the malaria parasite takes about 8 days to mature in the mosquito (depending on the species of Plasmodium), ITNs kill many mosquitoes before they are able to transmit the parasite to humans, once again curtailing transmission.
The big complaint about using bed nets of any kind is that they reduce air flow and are hot to sleep under, especially in tropical climates. This feature may discourage people from regularly using their bed net if they are not properly educated in the great benefits of this practice.
GHEI’s Health Program Assistant, Mensah Gyapong, commented on the prevalence of this particular challenge: “What we saw was that people were saying that the bed nets are very hot ‒ especially this time of year. They feel very uncomfortable inside the bed net. But we also find that there are a lot of mosquitoes at night, especially after midnight. We advise them that it is better to be a bit hot at night than to get malaria! At first people even removed the bed nets because of the heat, but now they are listening to our advice and are sleeping under bed nets even during the heat.”
A previous blog talked about the high price that children under five pay when it comes to malaria, with this age-group accounting for 90% of malarial deaths in sub-Saharan Africa. An older study carried out in The Gambia and reported in the medical journal The Lancet demonstrated that mortality rates due to malaria were 30% lower for young children who slept under a bed net than for those who didn't (Alonso et al. 1991). A more recent review of the literature reporting on ITN effectiveness concluded that, on average, ITNs reduce deaths in children by 20% and the episodes of malaria by 50% (Lengeler 2009).
The insecticide of choice for treating bed nets is pyrethroids (e.g., deltamethrin, permethrin). This class of insecticide is very effective against mosquitoes but is harmless for humans at the rate that it is used to treat the nets. This is important, since if you’re sleeping under a bed net, your body is right next to, or even touching, the netting. A growing problem is that in some areas where ITNs have been used, the mosquitoes are becoming resistant to pyrethroids. This means that the mosquito population has developed strains that aren’t killed by this insecticide, so that treated bed nets provide only a physical barrier to the mosquitoes. Research is under way to develop new insecticides for bed net treatment, but so far the test chemicals have not proven as effective as pyrethroids.
Another factor in the effectiveness of an ITN is how long the insecticide lasts. If people wash their bed nets or hang them out in the sunlight to air, as they would their bedding, the effectiveness of the insecticide is reduced. GHEI’s Community Health Workers have been spreading the message that bed nets should not be washed or exposed to sunlight.
Protection against mosquitoes can also be extended by using Long-Lasting Insecticide-Treated Nets (LLINs), which are effective for up to three years. The World Health Organization now recommends full coverage of all people at risk of malaria in areas targeted for malaria prevention with LLINs. The priority still remains the protection of children under five and pregnant women, but once these groups are covered, everyone in the program area should be given access to an LLIN.
Since 2006 GHEI has been committed to preventing malaria in Humjibre and the surrounding communities by distributing free insecticide-treated bed nets to community members. Previously, the GHEI health team, which includes the Humjibre, Kojina, and Soroano Community Health Workers (CHWs), distributed bed nets to every home in the three communities. Through GHEI’s universal distribution program, approximately 350 people in Kojina, 3800 people in Humjibre, and 900 people in Soroano have benefitted from bed net ownership and support for proper use.
GHEI’s Malaria Prevention Programme includes household monitoring of bed nets, during which the CHW observes the condition of bed nets in each home, re-hangs and mends bed nets as needed, educates household members on bed net care and usage, and encourages nightly usage of bed nets, especially for pregnant women and children under five years of age.
Sources:
Centers for Disease Control and Prevention. Insecticide Treated Bed Nets. http://www.cdc.gov/malaria/malaria_worldwide/reduction/itn.html
Lengeler, C. 2009. Insecticide-treated bed nets and curtains for preventing malaria. The Cochrane Collaboration. JohnWiley & Sons, Ltd.
World Health Organization. Global Malaria Program. Insecticide-Treated Mosquito Nets: A WHO Position Statement. www.who.int/malaria/publications/atoz/itnspospaperfinal.pdf
The more people that use insecticide-treated nets (ITNs) in a community, the greater the collective protection, or "spill-over effect", that is achieved. This benefit to the whole community, even to those not using bed nets, arises for two reasons. First, since ITNs kill mosquitoes, the more ITNs that are in use, the more mosquitoes will be killed, reducing the numbers that can transmit the malaria parasite. Secondly, since the malaria parasite takes about 8 days to mature in the mosquito (depending on the species of Plasmodium), ITNs kill many mosquitoes before they are able to transmit the parasite to humans, once again curtailing transmission.
The big complaint about using bed nets of any kind is that they reduce air flow and are hot to sleep under, especially in tropical climates. This feature may discourage people from regularly using their bed net if they are not properly educated in the great benefits of this practice.
GHEI’s Health Program Assistant, Mensah Gyapong, commented on the prevalence of this particular challenge: “What we saw was that people were saying that the bed nets are very hot ‒ especially this time of year. They feel very uncomfortable inside the bed net. But we also find that there are a lot of mosquitoes at night, especially after midnight. We advise them that it is better to be a bit hot at night than to get malaria! At first people even removed the bed nets because of the heat, but now they are listening to our advice and are sleeping under bed nets even during the heat.” A previous blog talked about the high price that children under five pay when it comes to malaria, with this age-group accounting for 90% of malarial deaths in sub-Saharan Africa. An older study carried out in The Gambia and reported in the medical journal The Lancet demonstrated that mortality rates due to malaria were 30% lower for young children who slept under a bed net than for those who didn't (Alonso et al. 1991). A more recent review of the literature reporting on ITN effectiveness concluded that, on average, ITNs reduce deaths in children by 20% and the episodes of malaria by 50% (Lengeler 2009).
The insecticide of choice for treating bed nets is pyrethroids (e.g., deltamethrin, permethrin). This class of insecticide is very effective against mosquitoes but is harmless for humans at the rate that it is used to treat the nets. This is important, since if you’re sleeping under a bed net, your body is right next to, or even touching, the netting. A growing problem is that in some areas where ITNs have been used, the mosquitoes are becoming resistant to pyrethroids. This means that the mosquito population has developed strains that aren’t killed by this insecticide, so that treated bed nets provide only a physical barrier to the mosquitoes. Research is under way to develop new insecticides for bed net treatment, but so far the test chemicals have not proven as effective as pyrethroids. Another factor in the effectiveness of an ITN is how long the insecticide lasts. If people wash their bed nets or hang them out in the sunlight to air, as they would their bedding, the effectiveness of the insecticide is reduced. GHEI’s Community Health Workers have been spreading the message that bed nets should not be washed or exposed to sunlight.
Protection against mosquitoes can also be extended by using Long-Lasting Insecticide-Treated Nets (LLINs), which are effective for up to three years. The World Health Organization now recommends full coverage of all people at risk of malaria in areas targeted for malaria prevention with LLINs. The priority still remains the protection of children under five and pregnant women, but once these groups are covered, everyone in the program area should be given access to an LLIN.
Since 2006 GHEI has been committed to preventing malaria in Humjibre and the surrounding communities by distributing free insecticide-treated bed nets to community members. Previously, the GHEI health team, which includes the Humjibre, Kojina, and Soroano Community Health Workers (CHWs), distributed bed nets to every home in the three communities. Through GHEI’s universal distribution program, approximately 350 people in Kojina, 3800 people in Humjibre, and 900 people in Soroano have benefitted from bed net ownership and support for proper use.
GHEI’s Malaria Prevention Programme includes household monitoring of bed nets, during which the CHW observes the condition of bed nets in each home, re-hangs and mends bed nets as needed, educates household members on bed net care and usage, and encourages nightly usage of bed nets, especially for pregnant women and children under five years of age. Sources:
Centers for Disease Control and Prevention. Insecticide Treated Bed Nets. http://www.cdc.gov/malaria/malaria_worldwide/reduction/itn.html
Lengeler, C. 2009. Insecticide-treated bed nets and curtains for preventing malaria. The Cochrane Collaboration. JohnWiley & Sons, Ltd.
World Health Organization. Global Malaria Program. Insecticide-Treated Mosquito Nets: A WHO Position Statement. www.who.int/malaria/publications/atoz/itnspospaperfinal.pdf
very nice. thanks
ReplyDeletesorif,
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