Treatment and use of Insecticide-treated Mosquito Nets

 Mosquito nets treated with insecticides—known as insecticide-treated nets (ITNs) or bednets—were developed and tested in the 1980s for malaria prevention by Dr. P. Carnevale and his team in Bobo-Dioulasso, Burkina Faso. ITNs are estimated to be twice as effective as untreated nets, and offer greater than 70% protection compared with no net. 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. For maximum effectiveness, ITNs should be re-impregnated with insecticide every six months. This process poses a significant logistical problem in rural areas. Newer, long-lasting insecticidal nets (LLINs) have now replaced ITNs in most countries

Insecticide treatment is recommended for synthetic nets (nylon, polyester), as treatment of cotton nets is not cost-effective and effect of insecticide is not long lasting. Insecticides used for mosquito nets are not harmful to people, if used correctly. Direct skin contact with the insecticide on a still wet net may cause a tingling sensation on the skin. This is not harmful, even for small children. After treatment, the net may smell of insecticide. This will go away in a few days and is not harmful to people who sleep under the net.

Long Lasting Insecticidal Nets (LLINS)

LLINs are mosquito nets which have the insecticide incorporated in their fibre, so that it is not removed by as many as 20 washes. Because these nets have an even and quality controlled insecticide application, they are generally more effective than conventional ITNs. Furthermore the LLIN is more cost-effective (as it can be used for 3-5 years) than distribution of conventional bed nets and treating them with insecticide once or twice a year. Conventional ITNs are therefore only a rational option in areas, where the population already has so many nets that at least 50% of people sleep under one.

Characteristics And Logistics Of LLINS

LLINs have different weight and volume characteristics as given in the table below:

Characteristics of LLINs relevant to logistics

Characteristics	Multi filament polyester LLIN (deltamethrin-coated)	Monofilament polyethylene LLIN (permethrin-incorporated)
Weight per LLIN	440 g	625 g
LLINs per bale	100	40
Weight per bale	42 kg	29 kg
Volume per bale	0.1727 - 0.1894 m3	0.127 m3
LLINs per 40-ft container	36,900	16,800

Those with responsibility for logistics must ensure adequate storage capacity and reliable transport at all levels, as well as precise timing. The planning of logistics must include a detailed budget for all transport and storage needs. Most importantly, logistic mechanisms must ensure adequate supervision and control of all operations and full accountability at every stage. It is recalled that LLINs are saleable; their diversion may have adverse effects on the programme at all levels.