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Malaria: Mosquitoes Are Fast Developing Resistance to Treated Nets – Research

Recent studies have shown that mosquitoes are becoming resistant to insecticide-treated nets (ITNs). Scientists say mosquitoes that are responsible for transmitting the deadly malaria parasite are fast becoming resistant to insecticide-treated Nets which have been able to cut down malaria cases by more than 20 percent. For this reason they say it has become very crucial that in order to continue to prevent or check the disease menace and avert a looming public health catastrophe, every effort must be made to stay ahead of the resistance.

Evidences abound that well affordable insecticide-treated mosquito bed nets have gone a long way to preventing malaria attacks which have usually lead to huge number of deaths as well as economic losses. Many at times pyrethroid insecticide-treated nets are being distributed freely to populations in malaria endemic regions especially in Africa and most parts of the tropics, and it has been a major defense against biting, malaria-bearing anopheles mosquitoes.

In 2015, it is reported by the World Health Organisation that malaria infected about 212 million people, out of which 429,000 of them were fatal. This shows a 21 percent crash considering the prevalence of between 2010 and 2015.

Buttressing the research findings for instance, a recent study published in the journal PLoS Genetics, established that the main mosquito that bears the parasite in southern Africa – Anopheles funestus, is fast becoming resistant to the insecticide. Reports say that in at least one country, Mozambique, scientists found that 100 percent of A. funestus continued to live even after it has been directly exposed to the chemical.

A mosquito geneticist at the School of Tropical Medicine in Liverpool, England, Charles Wondji, also states that resistance to insecticides made with pyrethroid took place rapidly – in about eight years. He pointed out that however, they have been able to identify the gene responsible for the resistance in the mosquito. A VOA source quoted him as saying that that will be an important tool which will enable scientists properly monitor the spread of insect resistance throughout Africa.

Wondji said, “That form of the gene is now very prevalent in southern Africa with the risk that if we do nothing there’s a chance that those control measures won’t work against those types of mosquitoes.” He stated that with this development, scientists would be able to clearly stay ahead of the “resistance curve” in areas where the insecticides are beginning to fail to kill off the malaria vectors. Experts are therefore suggesting that other more costly insecticides can as well be deployed to impregnate bed nets, such as a compound referred to as PDO; it aims straight at the gene, thereby killing the mosquitoes.

Yet, this is not the end of the threat or resistance to global malaria control and eradication efforts. More recent studies show other species of malaria-bearing mosquitoes, such as Anopheles gambiae, are also beginning to develop resistance to pyrethriods, albeit happening through a different biological method. Most ITNs are able to last for 6 months after which they must be discarded or re-treated with the insecticide which is deadly to the insects but harmless to humans and pets. But, most recently developed bed nets are meant to last for as long as 3 years; these are called LLINs, or long-lasting insecticide-treated nets. Yet unfortunately, experts observe that they are beginning to fail very fast.

Also, in a later development, the journal – The Lancet Infectious Diseases, in its publication reports that researchers in Thailand have discovered widespread malaria parasite resistance to artemisinin and combination therapies using artemisinin, which is seen as the utmost standard treatment for the disease. This clearly leaves us in no doubt that a lot more work needs be done especially on all species of mosquitoes.


Morgan Nwanguma

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