Cell Phones Used To Control Spread of Malaria

Globally nearly 3 billion people fall victim to malaria and nearly 1 million people die due to the dreaded disease with 90 percent of children in the Sub Saharan Africa afflicted by it.

Now, a modern gadget has helped researchers to map and target the disease. The cell phone data of 15 million people in Kenya was used to prepare detailed information on the spread of malaria.

The analysis by the researchers at Harvard School of Public Health (HSPH) and seven other institutions found that malaria, in large parts, emanates from Kenya's Lake Victoria region and spreads east, chiefly toward the capital, Nairobi.

"This is the first time that such a massive amount of cell phone data -- from millions of individuals over the course of a year -- has been used, together with detailed infectious disease data, to measure human mobility and understand how a disease is spreading," said senior author Caroline Buckee, HSPH assistant professor of epidemiology.

To curb malaria throughout Kenya, the disease-travel map points out precise areas for concentrating malaria control program.

According to Buckee, estimating malaria's potential spread not only provides information about the location of the mosquitoes that carry the malaria parasite, but also the behavior of the people who might be infected. He adds on saying, since many infected people have no symptoms, they can accidentally carry the parasite during their travels and infect hundreds of others.

The study was important as the insects tend to fly only about one kilometer throughout their short lives, but Kenyans are quite mobile. The Kenyans spend a lot of time in cities but have roots in the countryside, especially in towns along Lake Victoria. They travel a lot and thus contribute to the spread of malaria.

For the study, the researchers kept a track of every message call or text made by each of 14,816,521 Kenyan mobile phone subscribers to one of 11,920 cell towers located in 692 different settlements. This was done between June 2008 and June 2009.

Plus they calculated the duration and destination of each journey every time an individual left his or her primary settlement. With the help of the 2009 malaria prevalence map that was provided by co-authors at the Kenya Medical Research Institute (KEMRI) and the Malaria Atlas Project, they estimated the disease's prevalence in each location. They inferred each resident's probability of being infected and the daily probability that visitors to particular areas would become infected.

The researchers were astonished on finding large fraction of "imported" infections. Indicating infection is being carried by people moving from one place to another. These imported infections land up in Nairobi with infected residents returning there after journeys to spots such as Lake Victoria or the coast.

Buckee said, "By using disease prevalence data, researchers can estimate the probability that each person is carrying malaria parasites and build a map of parasite movements between "source" areas and "sink" areas.

"This kind of research coupling "big data" from mobile phones with detailed malaria incidence information will be an important tool for understanding the spread of the disease," said Buckee.

Buckee said, "Officials could send text message warnings to the phones of people traveling to high-risk areas, suggesting that they use a bed net."

The study appears in the October 12, 2012 issue of the journal Science.