University Florida logoEarlier this month we had reported about the fast diagnosis of acute appendicitis through smartphones. Mobile phones it appears also proved to be useful for University of Florida experts at work on a malaria elimination study in Africa. These scientists claim to have been able to use cell phone records to predict the spread of malaria.

Over 21 million calls were analyzed by the experts to ascertain the frequency of Zanzibar residents traveling and the places they are likely to visit. In recent years a semi-autonomous region comprising of two islands off the coast of Tanzania in East Africa, Zanzibar has shown a drastic dip in malaria cases. The study was commissioned by the region’s government to deliberate whether a total elimination campaign should be launched.

A close investigation of these calls indicated that most residents who left the region made short trips to Dar es Salaam on the Tanzanian mainland nearby. In this area malaria is known to be relatively uncommon. However a few Zanzibar residents were observed to have shuttled from more distant areas of Tanzania. These were places that had a higher risk of the disease possibly acting as that largest threat to elimination.

“That group of the population is the real risk if Zanzibar wants to eliminate malaria,” mentioned Andy Tatem, an assistant professor of geography, member of UF’s Emerging Pathogens Institute, and lead author. “That is the population group that is likely to be continually reintroducing infection.”

Though malaria is not known to pass on from person to person, once infected elsewhere, travelers may be bitten by mosquitoes when they are back in Zanzibar. These mosquitoes could then forestall elimination by flying on to bite and infect other Zanzibar residents.

In the past decade malaria infections in Zanzibar seem to have reduced from as much as 40 percent of its 1.2 million people to less than 1 percent thanks to the region’s aggressive campaign. Most Zanzibar residents are known to travel to and from mainland Tanzania through four- to six-hour ferry trips. However records of their origin and destinations seem to be poor according to Tatem. Along with five colleagues, he obtained records of three months of calls from customers of the Zanzibar Telephone Company, which covers all of Zanzibar and Tanzania. He was inspired by recent cell phone-based epidemiological research in Europe for this.

Containing no names or other tracking information, the October-December 2008 records claimed to have kept a tab on the movements of 770,369 customers. It exhibited each customer’s calls and their origin calls. It appeared that most callers never left Zanzibar, means they posed no threat of reintroducing the Malaria parasite. Tatem further revealed that about 12 percent did leave the islands, however most of them only visited relatively safe Dar es Salaam. Their visits lasted for just one or two days at a time. But a few hundred residents were found to have made trips to regions of western and southern parts of Tanzania. As many as 40 percent of the residents appeared to have the malaria parasite.

These cell records claimed to have no information about the dangers from non-residents visiting Zanzibar. Most visitors to the region seem to be tourists who either come from countries where malaria is not a problem or are taking anti-malarial drugs. They thus appear to pose little threat for malaria importation. Tatem adds that mainland residents visiting for work however may be carriers of infection and hence future work will be needed to assess these risks as well.

According to Tatem, the study should offer Zanzibar’s government various options to move forward with elimination. Zanzibar residents could be chosen by the government for administration of prophylactics against malaria before they travel. They could also conduct screenings of all the residents as they return. Both the propositions are considered to be very expensive. A targeted information and/or screening campaign aimed at the high-risk travelers could also be launched.

A paper on the research is likely to appear in the January issue of the Malaria Journal.