1According to a 2015 WHO report, 457 million cases of malaria were averted thanks to the use of insecticide-treated mosquito nets. This remarkable result was partly due to the hundreds of millions of long-lasting impregnated mosquito nets widely distributed in malaria infected areas over the past few years. To this day, pyrethroid-treated mosquito nets are still the only truly operational vector control method, guaranteeing personal, family and community protection.

In front of the mosquito net, Benin.

2It all began in 1983 in the medical entomology department of Bobo-Dioulasso’s Muraz centre in Burkina Faso, when a team of medical entomologists tested a new control method aimed at killing mosquitoes before the bite, when the conventional method (insecticide on the walls) killed mosquitoes after the bite!

3It was a simple technique: soaking mosquito nets in a basin containing water and a pyrethroid insecticide (permethrin). After hanging these impregnated mosquito nets in experimental huts of the Soumousso station, researchers found that they greatly reduced contact between humans and mosquitoes: they limited the amount of mosquitoes coming in, killed many of those who got in and increased the exit rate, thereby preventing sleepers from being bitten. That was the desired goal!

4This team then carried out initial epidemiological assessments in Burkina Faso, demonstrating that impregnated mosquito nets reduced the transmission of malaria parasites by 90% and the number of cases in children by 50%. At the time, however, the majority of the scientific community was sceptical, being more hopeful about the “impending” discovery of a malaria vaccine – which is still pending.

••• In the 1980s, the development of pyrethroid-treated mosquito nets revolutionised malaria vector control methods. •••

Checking a mosquito net, Benin.

5Following the first scientific publication of these results in 1984, researchers from various organisations came to Bobo-Dioulasso to learn about the technique, after which they developed control programmes in several countries, confirming this reduction in transmission and a 50% drop in malaria morbidity.

6A wide-ranging study was subsequently conducted in Gambia, Ghana and Kenya, demonstrating that widely used impregnated mosquito nets reduced overall infant and child mortality by 20%. This key argument gave fresh impetus to vector control and the integration of impregnated mosquito nets into national malaria control programmes.

7Encouraged by these results, in the 1990s industrial companies started manufacturing “long-lasting” impregnated mosquito nets (lasting three to five years), currently distributed on a very large scale in malaria infected countries with great success.

“From 2001 to 2015, more than 663 million cases of malaria were averted thanks to various control operations. Insecticide-treated mosquito nets had the greatest impact, accounting for 69% of averted cases, according to official estimates.” 
Extract from the WHO’s press release, World Malaria Day, 25 April 2017