Long-Lasting Insecticide-Treated Nets (LLIN) - Malaria Prevention and Control

Introduction

Malaria is caused by a plasmodium parasite transmitted to people through the bites of infected Anopheles mosquitoes. In 2020, malaria cases worldwide were estimated to be 241 million, and the number of deaths from malaria was 627000. The majority of the population affected were young children in Africa. However, within the last decade, many organizations and resources have increased many preventive measures to control the malaria mortality rate. Some preventive measures WHO (world health organization) recommended include malaria vaccines for children, preventive drugs, and insecticide-treated bed nets.

What Is Malaria?

Malaria is a severe and life-threatening disease caused by the plasmodium parasite, transmitted through the bite of an infected female anopheles mosquito. When a female anopheles mosquito bites a person with malaria, it carries the parasite in the person’s blood. When it bites another person, it injects the parasite into them and causes the spread of the disease.

What Causes Malaria?

The plasmodium parasite species causes malaria. Five Plasmodium species can affect humans; two are considered the most dangerous: Plasmodium falciparum and Plasmodium vivax. Plasmodium falciparum multiplies very quickly and causes severe blood loss and clogged blood vessels, whereas Plasmodium vivax may remain dormant for months or years after the mosquito bite.

Malaria is not contagious and cannot spread from person to person, but it can spread:

• From a pregnant mother to an unborn child.

• Using shared needles.

• Blood transfusion.

• Organ transplant.

Where Is Malaria Most Common?

Malaria is common in poor tropical and subtropical areas of the world. It is most common in places with warm climates.

It is found in:

• Africa and sub-Saharan Africa.

• Southeast Asia.

• Middle East countries.

• Central and South America.

• Oceania.

What Are the Signs and Symptoms of Malaria?

Malaria symptoms are usually ten days to a month after the mosquito bite. However, the symptoms may vary from mild to severe depending on the Plasmodium species involved.

Symptoms may include:

• Diarrhea.

• Malaise.

• Nausea.

• Body aches.

• Fatigue.

• Kidney failure.

• Seizures.

• Confusions.

• Blood in the stool.

• Jaundice.

• High fever.

• Chills.

• Sweating.

What Are the Different Malaria Prevention Methods?

WHO has recommended various methods and strategies to prevent malaria, including vector control, preventive malarial drugs, and vaccines.

Vector Control: It is an essential component of malaria control and elimination strategies in preventing the spread of the disease. It includes indoor residual sprays (IRS) and insecticide-treated nets (ITN).

Preventive Medications: It is the use of drugs, either alone or in combination, to prevent malaria infections and their complications. Preventive medications include intermittent preventive treatment of infants (IPTi), intermittent preventive treatment of pregnant women (IPTp), chemoprophylaxis, seasonal malaria chemoprevention (SMC), and mass drug administration (MDA).

Vaccines: WHO recommends malaria vaccine among children living in moderate to high-risk regions with Plasmodium falciparum transmission. It has been effective in reducing malaria among young children.

What Are Insecticide-Treated Nets (ITN)?

Insecticide-treated nets (ITN) around the bed are a form of personal protective method that effectively reduces malaria illness, severe diseases, and death due to malaria in endemic regions. Insecticide-treated nets have effectively reduced the death of children under five years of age by about 20 % in a community trial in several African settings. These are polyester, polyethylene, or polypropylene nets treated with only two classes of insecticides: pyrroles and pyrethroids. Pyrroles and pyrethroids have been shown to cause very low health risks to humans and other mammals but are deadly for insects. The ITNs must be retreated every six to 12 months by simply dipping them in a mixture of insecticide and water and allowing them to dry in a shady place. However, the additional cost of retreatment and the lack of knowledge about its significance resulted in low retreatment rates and less effective in most African countries. To help manage this, several companies developed long-lasting insecticide-treated nets (LLIN).

What Are Long-Lasting Insecticide-treated Nets?

Since retreating ITNs frequently had become ineffective in many African countries, several companies developed long-lasting insecticide-treated nets that remain effective for at least three years, even after washing repeatedly. In addition, the WHO pesticide evaluation scheme (WHOPES) has approved over 15 LLINs for use to prevent malaria. LLINs not only block the mosquitoes through the netting but also kill them using insecticide, forming a physical and chemical barrier against mosquitoes. The WHO recommends that LLINs need to be distributed to and used by all people in malaria-prone areas and are hence distributed every three years through mass campaigns.

What Are the Different Types of LLINs?

Long-lasting insecticide-treated nets are usually made of polyester or polyethylene nets treated with insecticides.

Currently, there are three LLINs recommended by the WHO pesticide evaluation scheme:

• Olyset Net: It is 2 % permethrin-treated polyethylene fibers.

• Perma Net: It is treated with 55 mg/m2 of deltamethrin to coat fibers.

• Interceptor: It is 200 mg alpha-cypermethrin per square meter of polyester netting.

Later the conventional LLINs were incorporated with piperonyl butoxide (PBO), a synergist that partially restores pyrethroid susceptibility in mosquitoes. LLINs with PBO include PermaNet 3.0 and Olyset Plus.

How to Use LLINs?

Before using an LLIN, hang it on a stick or a tree or somewhere to air out for at least one day.

While hanging the LLIN:

• Hang it using the strings provided on the corner or the middle of the net.

• Tuck in the net under the mattress or mat so the mosquito has no gaps to enter.

• Flip up the net during the day to avoid it getting damaged.

• Do not use fire near the treated net.

• Do not let the net in the sun for long during the day, as the sunlight may weaken the insecticide.

How to Maintain the LLIN?

• Avoid frequent washing of the nets; wash them only when it is dirty with soap and water. Washing three times a year or even once a year would be sufficient.

• Re-treat the nets with insecticides before the rainy season.

• Dry the nets in shady places.

• Sew torn areas of the net before it gets bigger so the mosquitoes cannot enter inside.

Conclusion

Long-lasting insecticide-treated nets are an effective way to prevent mosquito bites and resultant malaria. Good maintenance and storage could improve the efficacy of the LLINs and prevent malaria to a greater extent. Protect oneself and one’s family from mosquitoes and malaria by using the nets every night, year-round.