Technical Details

Providing Insecticide Treated Nets sets off a virtuous cycle.

For every life saved from malaria, THREE lives are spared from other diseases.

Why Nets Work

Insecticide Treated Nets perform two basic functions: they form a barrier and the insecticide kills or repels mosquitoes. Sleeping under insecticide treated nets works so well because mosquitoes bite their victims at night, mostly between 9 pm and 3 am. Insecticides repel the mosquitoes by making them feel sick so that they fly away. If the mosquito touches the net, she will probably die. Even if she doesn't die, if she touches a net she usually will fall to the ground and be eaten by other insects or get crushed underfoot. The life of mosquitoes is perilously short.

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The 10 Day Rule
The malaria parasite must mature in the mosquito for 10 days. This is the 10-day rule. Therefore, mosquitoes that have dined on infected blood are not immediately infectious. The 10 day period includes at least 5 and perhaps as many as 50 bloodmeals. If a single one of those feedings includes a meaningful encounter with a treated net, the mosquito dies before she becomes infectious.

Mathematically gifted analysts tell us that this 10 days/ 5+ feedings means that not everyone must sleep under a mosquito net to interrupt transmission. These analysts only give probabilities, so I haven't gotten a straight answer from any such analyst, but coverage of 50% of the people seems enough, according to most studies, to lower the rates of malaria dramatically.

We may never know whether covering exactly 50% or 38.2% of a given population with nets is the magic number to interrupt transmission. What we do know is that at some point of coverage, we interrupt transmission completely. Is that point 68% or 73% or 92%? We do not know. The point may vary with local conditions. At some point, the ITNs could kill enough mosquitoes early enough to stop reinfection almost completely. Transmission is interrupted. Malaria is gone until it is re-introduced.

Once Interrupted, Killer Malaria Burns Out
The other key to understanding malaria transmission is that the parasite, if not reintroduced to the human, will usually 'burn itself out' in about 120 days. We are talking about the deadly plasmodium falciparum variety of malaria in this case. What does that mean? If we can keep a group of people from getting or transmitting malaria for a few months, perhaps a malaria season, where transmission is seasonal, there may be no more parasites in the human reservoir to go around in the first place. You got it.

Insecticide Treated Nets

Why ITN coverage is important: Malaria has been repeatedly proven to be a lynchpin disease. Lowering malaria addresses several other problems, not simply other diseases. Yes, providing bednets would lower the sickness from malaria by about half. In addition, full coverage of nets would:

A. Save 250,000 lives annually from malaria.

B. Save 700,000-1,250,000 million more lives per year in Africa from other diseases (Studies consistently show a 20-30% decline in child mortality overall from ITNs, even without adding medicines).

C. Cut all hospital visits by 25-40%, freeing up funds and personnel to be redirected strategically at other health problems, such as HIV/AIDS and TB.

D. Free up energy of families, health care workers and whole countries.

Note: The Measles Initiative already adds selected other inputs such as medicines and vitamins. Including certain other inputs could save yet another 100-500,000+ lives a year.

Comorbidity

ITNs lower rate of deaths from all causes. The technical term for this is 'comorbidity'. If your child is sick with one thing, say, pneumonia, and then gets malaria, she is more likely to die from one of them. Whether you call the cause of death malaria or pneumonia is a matter for statistics. Regardless, your child is still dead.

For every life saved from malaria, THREE lives are spared from other diseases.

ITNs as a Symbol

Treated bednets are a visible symbol for families and communities, symbols that show they take responsibility for improving their personal health. What is important is that the families participate, that they lead themselves out of misery. In the Lawra District Campaign, of those who reported receiving an ITN, 216/222 (97.8%) were observed to have a campaign net in their home 5 months post-distribution. Only 2.2% reported having sold the net.

When Rotarians put a single net into every home in Lawra District, Northwestern Ghana, hospital visits went down by 40%.

Small Things Make a Big Difference

Mosquito nets are visible signs of caring, however small. In this new century we learn again and again that small things may matter the most. When they fixed broken windows and cleaned up graffiti in New York City, such seemingly small things, the murder rate dropped from over 2000 per year to under 100 homicides in 2003. ITNs are a small thing that will make a big difference. They will drop the death rate dramatically.

Only the future will tell what is most important to them - or to us.