17 August 2010
The ancient disease of malaria continues to be a scourge that sickens millions worldwide annually.
There are many ways to stop the spread of the disease.
You can kill the mosquitoes that spread it with insecticide, or you can treat the people who have it with drugs, or you can prevent mosquitoes from biting you by sleeping under an insecticide treated bed net.
But what's the most effective way for a cash-strapped country or province to control malaria for the most people, at the least cost?
Policy makers and researchers continue to look for ways to maximize the impact of control campaigns, while minimizing the cost. One way to determine which strategies work best is through sophisticated mathematical modeling - such as those created by Azra Ghani.
Ghani is an infectious disease epidemiologist at Imperial College London. She has spent years creating computer simulations devised to help health system planners curb the spread infectious diseases. Ghani says the same can be done with malaria.
"What we are particularly interested in looking at is trying to combine these different interventions that we know are now taking place and say, 'If we put bed nets in at a certain coverage, or if we instead decide to spray houses, how will that reduce transmission?'"
Ghani and her colleagues used real-world data about malaria to create such a mathematical model.
The data showed that, in areas where transmission of the disease from person to person was low, simply using insecticide treated bed nets was enough to reduce the number of people with malaria to only a few.
However, in areas with high rates of disease, there must be more interventions and more concerted efforts to just reduce the number of people with malaria.
"Obviously there are limited costs and one of the very important messages is that these interventions aren't just something that we can put in for a year or even five years, hope to see results and then stop doing," Ghani says. "They need very long-term commitment. Any of the programs that we looked at to have a really big effect... really needed to be in effect 15, 20 years or more."
In addition to modeling which interventions work for different places, Ghani created a computer program that can be easily used by policymakers in different countries.
"And people that are planning the control programs can go in and say, 'Well, what if I put in 80 percent coverage of bed nets?'" Ghani says. "And this intervention and that intervention together, what impact will I have? So, it can be generalized for those policymakers."
Ghani says this type of tool can help public health officials make the best decisions to control malaria - for their particular situation - over the long run.
The paper, and access to a downloadable computer program, are available at the online journal, PLoS Medicine.