The spread of malaria is dependent on Anopheles mosquitoes that spread the disease, and it persists in places where these types of mosquitoes exist and where there are enough people to keep the parasite thriving in humans. Human movement between locations can lead to the movement of malaria parasites across long distances, and when malaria parasites are transported to places that have the right kind of mosquitoes, they can persist in those new places.
In a paper recently published in Malaria Journal, global health researchers, Daniel Parker, PhD, assistant professor, and Guiyun Yan, PhD, professor, both from the UCI Program in Public Health, analyzed the movement ecology of humans in two places of heightened importance for Ethiopia’s malaria control and elimination strategies: Gambella and Benishangul-Gumuz (on the international border with Sudan and South Sudan).
Ethiopia has a unique landscape in that its population centers tend to be in high elevation places; places that have historically been too cold (for at least part of the year) for malaria spreading mosquitoes to thrive. This is likely changing because of climate change.
The two regions that Parker and Yan looked at consistently have the highest burdens of malaria in the nation. Movements of people between these regions can likewise lead to transportation of parasites to other regions. This can lead to disruptions in local public health successes by reintroducing parasites to places that have controlled malaria but still have the right mosquitoes to spread the disease. Increasingly, it could lead to the introduction of parasites in places that only recently have the right kind of mosquitoes to spread malaria – which could catch some previously non-malarious places by surprise.
Using cellular network data to inform malaria elimination strategies
The researchers partnered with Ethiotelecom, the sole mobile phone provider in Ethiopia, to access anonymous, population-level data on mobile phone handovers (when a person’s mobile phone moves between cell phone towers). Those cell phone towers can be located on a map, meaning that cell phone handovers can be mapped and also quantified by the hour, month, or other time stamps.
We also found hourly patterns of movements that peaked twice daily, in the morning and late afternoon – much like the rush-hour traffic that we experience here in California.
– Daniel Parker, PhD
“We found several interesting patterns in our analysis of human movements. Not surprisingly, places with large amounts of movements were normally around population centers. A few of these locations were along international borders, likely indicating cross-border movements,” explained Parker. “We also found hourly patterns of movements that peaked twice daily, in the morning and late afternoon – much like the rush-hour traffic that we experience here in California.”
This hourly pattern has significance for one of the most widespread malaria interventions: bednets, which are convenient and effective at protecting individuals from malaria spreading mosquitoes. However, bednets are most commonly used at night while people are sleeping. The mobile phone data show that there are significant numbers of people moving early in the morning and late in the evening, at times when malaria spreading mosquitoes in this region are actively feeding.
The monthly cell phone data also showed large amounts of in and out movements during the rainy season in these two highly malarious regions. These are times when people in Gambella and Benishangul-Gumuz have higher probability of acquiring a malaria infection, and for those who are subsequently moving out of the region – times when they may transport parasites to other regions.
“This is just the beginning of our work along these lines, but already we believe that these results show the usefulness of using anonymous phone records for quantifying the geographic and temporal patterns in human travel – and for thinking about designing public health interventions that incorporate this kind of information,” concluded Parker.
Additional collaborators include corresponding author Werissaw Haileselassie, Ashagrie Getnet, and Wakgari Deressa with the Addis Ababa University and Hiwot Solomon with the Ethiopia Ministry of Health.
