Researchers create worldwide database for malaria transmission

University of Florida researchers have created the first worldwide database for malaria transmission.
Written by Boonsri Dickinson, Contributing Editor

University of Florida researchers have created a worldwide database for malaria transmission, a tool that could be used to see just how feasible it is to eliminate malaria from endemic countries.

Professor Andrew Tatem at the university's Emerging Pathogens Institute pulled together information gleamed from 30,000 individual surveys taken from the ground and used a computer model to construct a map of the data.

Tatem used the map to figure out how feasible it is to eliminate the transmission of the deadliest form of the parasite that causes malaria.

His findings:

  • 32 of the 99 countries that still have endemic malaria have begun to eliminate the disease from within their borders.
  • Countries in South America appear to be in the best position to succeed at elimination.
  • Many sub-Saharan African nations -- Angola, Chad, Somalia, and the Democratic Republic of Congo -- rank low for feasibility of malaria elimination, mostly due to unstable governments and systemic poverty.
  • If countries can get the transmission rates to become half of what they were in 2007, then it's possible that the deadly strain of malaria could be eliminated in problematic parts of the world in the next decade.

All it takes is one blood sucking female mosquito to infect a person with its deadly parasite, Plasmodium falciparum. This is precisely how half a billion people a year are infected with the mosquito-borne illness, malaria.

There's a life cycle to the transmission of malaria. First, a single sporozoite makes its way down and settles into a liver cell, where the parasite begins to grow. It only takes six days to produce tens of thousands of daughter cells.

Once the cell bursts, the daughter cells launch their own attack on the body by finding a red blood cell to infect. There, it only takes two days for the parasite to replicate into 8-24 more daughter cells and the blood invasion continues as long as the blood cells keep rupturing.

The chance of transmission depends on where exactly you are in the world. In the states, only 1,500 cases are reported annually. Malaria was eliminated half a century ago here. (Thanks to a successful effort by the National Malaria Eradication Program, it only took four years to get rid of malaria in our nation. By 1951, the United States declared victory over malaria.)

To date, 75 countries have eliminated malaria. Thirty-two are on track to follow suit in the next 10 years.

While the war on malaria isn't over, the new database might help make the fight a little more calculated. The paper was published in journal The Lancet's Malaria Elimination Series.

"There's never been a quantitative evidence-based guiding policy on malaria elimination," Tatem said. Before, experts could only make rough estimates of malaria transmission around the world.

Historically, malaria was a problem in the army, when troops routinely set up their camps in mosquito breeding grounds.

The illness has been well documented, way before people suspected the parasites transmitted through mosquito bites were to blame. Its name comes from bad air: "Mal-air-ia."

Early one morning in 1880, while Dr. Alphonse Laveran was at a military hospital in Constantine, he discovered the malaria parasite in a patient's blood. Later he looked for the parasite in the air, water and soil with no luck, so Laveran figured out the parasite resided in the body of mosquitoes.

Today, the aim of malaria elimination is to stop the transmission cycle of the parasite. There are several strategies, including encouraging people to sleep under insecticide treated nets.

While many nations have set goals to eliminate malaria, there has not been a real global assessment of how to go about doing this until now.

Tatem cautioned countries to use the information available first before they go ahead and launch an expensive, elimination program. In fact, countries interested in an elimination program should look to Zanzibar as a model - the country recently completed an elimination feasibility assessment.

Infections are brought in when countries have:

  • health-care deficiencies
  • political instability
  • high transmission rates
  • neighboring populations that frequently cross the border

That's why ninety percent of the deaths occur in Africa, Tatem said.

"In some parts of the world, where malaria is nonexistent, they might not think it's a problem," he said. "But it still kills a million people a year."

This post was originally published on Smartplanet.com

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