The scientists analyzed more than 21 million calls to determine how often residents of Zanzibar travel and where they go. A semi-autonomous region composed of two islands off the coast of Tanzania in East Africa, Zanzibar has drastically reduced malaria in recent years. Its government commissioned the study as part of deliberations on whether to launch a total elimination campaign.
The calls indicated that most residents who leave the region make short trips to Dar es Salaam on the Tanzanian mainland nearby, where malaria is relatively uncommon. However, they also revealed that a few Zanzibar residents travel back and forth from more distant areas of Tanzania where the risk of getting the disease is much higher — posing the greatest threat to elimination.
“That group of the population is the real risk if Zanzibar wants to eliminate malaria,” said Andy Tatem, an assistant professor of geography, member of UF’s Emerging Pathogens Institute, and lead author of a paper on the research likely to appear in the January issue of the Malaria Journal. “That is the population group that is likely to be continually reintroducing infection.”
Malaria is not transmissible from person to person. But if infected elsewhere, travelers can be bitten by mosquitoes once back in Zanzibar — and those mosquitoes could then fly on to bite and infect other Zanzibar residents, forestalling elimination.
Over the past decade, Zanzibar’s aggressive campaign against malaria has reduced infections from as much as 40 percent of its 1.2 million people to less than 1 percent, Tatem said. The country is weighing the cost of a campaign to eliminate the disease against the cost of continuing indefinitely with the control measures now in place. Its government commissioned what Tatem described as Africa’s first “elimination feasibility study,” including the travel research.
Most Zanzibar residents journey to and from mainland Tanzania via four- to six-hour ferry trips, but records of their origin and destinations are poor, Tatem said. Inspired by recent cell phone-based epidemiological research in Europe, he and five colleagues obtained records of three months of calls from customers of the Zanzibar Telephone Company, which covers all of Zanzibar and Tanzania.
The October-December 2008 records, which contained no names or other identifying information, tracked the movements of a 770,369 customers by showing each customer’s calls and where the calls originated — or at least the region where the call originated.
So, for example, the researchers could see that a person made calls from Zanzibar’s main city of Stone Town Monday, Tuesday and Wednesday, but on Thursday and Friday from Dar es Salaam.
Most callers never left Zanzibar, which means they posed no threat of reintroducing the Malaria parasite, Tatem said. About 12 percent did leave the islands, but most of those only visited relatively safe Dar es Salaam, and usually for just one or two days at a time.
However, a few hundred residents made trips to regions of western and southern parts of Tanzania, where as many as 40 percent of the residents have the malaria parasite.
The cell records did not reveal any information about the threat from non-residents visiting Zanzibar. Many visitors to the historic center of the spice trade are likely to be tourists who either come from countries where malaria is not a problem or are taking anti-malarial drugs, so pose little threat for malaria importation. However, mainland residents visiting for work may carry infections, so future work will need to assess these risks too, Tatem said.
Tatem said the study gives Zanzibar’s government several options should it move forward with elimination. The government could choose to give Zanzibar residents prophylactics against malaria before they travel, or it could screen all residents as they return, both very expensive propositions. Or it could launch a targeted information and/or screening campaign aimed at the high-risk travelers.
Zanzibar will use the study in combination with another study — of the challenges and costs of eliminating the remaining infections within the country — to make its decision.
“Going for elimination can be very expensive, much more expensive than continuing with current sustained control, involving giving people bed nets (to protect against mosquito bites at night), spraying the inside of houses with insecticide and providing anti-malarial drugs,” he said. “But in the very long term the savings having no malaria may outweigh those costs.”
Andy Tatem | EurekAlert!
Antarctic Ice Sheet mass loss has increased
14.06.2018 | Technische Universität Dresden
WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
22.06.2018 | Materials Sciences
22.06.2018 | Earth Sciences
22.06.2018 | Life Sciences