Emory Developing New Approach to Control Dangerous Urban Mosquito in Ethiopia
Combining satellite data, AI, ecology and sociology to zero in on a malaria vector
Emory University received $2.8 million in funding from the Gates Foundation to support its work to develop and test a high-tech, low-cost method to control an invasive mosquito that poses a growing threat of urban malaria in Africa. The three-year project is focused on three cities in Ethiopia: Jigjiga, Semera and Logiya.
The project’s novel approach to combating malaria combines on-the-ground knowledge of human and mosquito behaviors with detailed environmental imagery from drones and NASA satellites. Machine learning techniques will be applied to the data to develop a model — powered by artificial intelligence — for targeted public health interventions.
The aim is to efficiently control populations of the invasive Anopheles stephensi mosquito by first, identifying water sources that are most likely to harbor the larvae during the dry season. Second, the researchers will share maps of these precise targets with local public health authorities — via a mobile phone app — to guide their larvae-eradication efforts in the most efficient and effective manner.
The strategy is based on research on the ecology of stephensi in Jigjiga led by Gonzalo Vazquez-Prokopec, Emory professor of environmental sciences and co-principal investigator for the project.
“It sounds counterintuitive to focus mosquito-control efforts on the dry season,” Vazquez-Prokopec says. “Our research, however, shows that the dry season offers a perfect window of opportunity to cost-effectively control these mosquitoes.”
Emory disease ecologist Gonzalo Vazquez-Prokopec (left) with Solomon Yared, a medical entomologist at Jigjiga University, one of the partner institutions on the project. They are pictured during a recent visit by Yared to the Emory campus.
Emory disease ecologist Gonzalo Vazquez-Prokopec (left) with Solomon Yared, a medical entomologist at Jigjiga University, one of the partner institutions on the project. They are pictured during a recent visit by Yared to the Emory campus.
Vazquez-Prokopec is an expert on the disease ecology of pathogens spread by vectors, such as mosquitoes. His research considers environmental factors as well as the interactions of mosquitoes, the pathogens they carry, and people.
Xiao Huang, Emory assistant professor in environmental sciences and an expert in AI, remote sensing and satellite-image processing, is co-principal investigator for the project. Jola Ajibade, Emory associate professor of environmental sciences and an expert in human geography and social sciences research in urban areas, is a co-investigator.
Partners on the grant include scientists from NASA; Jigjiga University; University of Addis Ababa; Addis Ababa University; and developers of the Zzapp software system for map-based mobile apps for mosquito control.
Project members arrive at a construction site to search for mosquito larvae. Their research has shown that the major habitats consistently infested with stephensi larva are manmade pits used to store water at these sites, which are proliferating due to building booms. Africa is the most rapidly urbanizing continent.
Project members arrive at a construction site to search for mosquito larvae. Their research has shown that the major habitats consistently infested with stephensi larva are manmade pits used to store water at these sites, which are proliferating due to building booms. Africa is the most rapidly urbanizing continent.
Local team member Selam Yemane, shown in front of a traditional house in Logiya, prepares to check a tire for stephensi adults using a "mosquito vacuum" known as the "Prokopack." The device was invented in 2009 by the Vazquez-Prokopec lab using inexpensive parts found at hardware stores. Yemane is serving as a project liaison with owners of businesses and residences who are allowing scientific sampling on their properties.
Local team member Selam Yemane, shown in front of a traditional house in Logiya, prepares to check a tire for stephensi adults using a "mosquito vacuum" known as the "Prokopack." The device was invented in 2009 by the Vazquez-Prokopec lab using inexpensive parts found at hardware stores. Yemane is serving as a project liaison with owners of businesses and residences who are allowing scientific sampling on their properties.
A water cistern at a construction site. During the dry season, water trucks replenish these cisterns, providing habitat for mosquito larvae.
A water cistern at a construction site. During the dry season, water trucks replenish these cisterns, providing habitat for mosquito larvae.
Edilawit Mesfine (left) and Edel Seifu, both from Jigjiga University, collect data and larvae from a cistern at a construction site.
Edilawit Mesfine (left) and Edel Seifu, both from Jigjiga University, collect data and larvae from a cistern at a construction site.
Malaria annually kills around 600,000 people globally, mostly in Africa, according to the World Health Organization.
Stephensi, long a major vector of malaria in Asia, was first identified in Africa in 2012 in Djibouti, a country that serves as a major port on the Horn of Africa. The mosquito has since been detected in Ethiopia, Somalia, Kenya, Nigeria and Ghana. It has already sparked several urban outbreaks of malaria in Africa.
The invader brings a challenging new twist to malaria eradication efforts in Africa. For much of the continent, malaria is mainly a rural disease, primarily spread by other species of mosquitos that are adapted to live in rural areas. African public health officials have made great strides controlling the disease, using methods targeting the unique behaviors of these rural mosquitos and the lifestyles of people in the countryside.
Stephensi, however, is a game changer. This species of mosquito can live in rural environments but also thrives in urban areas. It’s resistant to insecticides and adept at surviving dry seasons. Its arrival in Africa poses a serious potential threat to millions of city dwellers who have little or no immunity from repeated prior exposure to malaria.
Stephensi was first detected in Jigjiga in 2018 and has persisted there despite harsh dry seasons of around three rainless months from December to March.
“It’s an extremely arid part of the world,” Vazquez-Prokopec says. “The only way the mosquito larvae can survive the dry season is to find water sources that are replenished.”
Curious children gather to watch as the researchers inspect mosquito larvae gathered from a pool of water at a construction site.
Curious children gather to watch as the researchers inspect mosquito larvae gathered from a pool of water at a construction site.
In 2022, funded by a seed grant from the Emory Global Health Institute, Vazquez-Prokopec began leading an international team — including local scientists from Jigjiga University and Addis Ababa University — to determine which water sources harbored the most stephensi larvae.
The team searched for standing water during the dry season at locations across the city to sample for mosquito larvae. They found that the major habitats consistently infested were the manmade pits used to store water at construction sites and small-scale, brick-making facilities.
These cisterns, sometimes not much bigger than a children’s wading pool, are made of earthen or concrete walls, sometimes draped in plastic sheeting. Water trucks replenish the cisterns during the months-long process of construction, to use for processes such as mixing and curing concrete.
Data collected by the team revealed construction cisterns containing algae growth produced far more larvae compared to those with no algae. Water clouded with sediment was a secondary factor favoring the presence of larvae, although not nearly as strong an indicator as algae.
The researchers entered the GPS coordinates of the construction cisterns into Google Earth to visualize their locations. It became apparent that the sites provided a unique spectral signature in the satellite imagery — demarcated by size, color contrast and the presence of water — that allowed the researchers to easily identify other construction pits throughout Jigjiga.
The work funded by the Gates Foundation aims to build on these findings.
Xiao Huang records the GPS coordinates for a construction site cistern containing algae. Huang is focused on aspects of the project involving AI, remote sensing and satellite-image processing.
Xiao Huang records the GPS coordinates for a construction site cistern containing algae. Huang is focused on aspects of the project involving AI, remote sensing and satellite-image processing.
The researchers are expanding to the cities of Semera and Logiya and collecting more detailed data on water sites most likely to harbor stephansi larvae.
“NASA satellite imagery gives us a view from space at a resolution of one-third meter,” Huang says. “We can also use satellite imagery to calculate the turbidity and percentage of algae in a water body.”
The chlorophyl in algae, he explains, reflects the near-infrared light of the satellite remote-sensing energy while silt in the water absorbs it, providing measurable indices.
The researchers will fly drones across the city to capture additional geographical details.
Data on environmental parameters such as the presence of roads, houses and other structures, the amount of trees and vegetation and average temperatures will be collected.
Huang will use machine learning techniques to train an algorithm in object recognition to detect the construction cisterns. Data on percentage of algae, turbidity and environmental parameters will be used to further develop the algorithm to rank the water sites from the highest-to-lowest probability for containing stephansi larvae.
The result will be a map pinpointing the highest priority sites for treatment with a slow-release, biological larvicide that lasts for six months and is harmless to humans. Local public health workers will have access to the map via a mobile phone app to make their work as efficient and effective as possible.
Jola Ajibade will focus on sociological aspects of the project. “We want to engage members of the local community in the process of developing the project to make sure we understand their needs,” she says. (Photo by Carol Clark)
Jola Ajibade will focus on sociological aspects of the project. “We want to engage members of the local community in the process of developing the project to make sure we understand their needs,” she says. (Photo by Carol Clark)
Surveys and interviews will be conducted among various stakeholders, including residents, construction workers, local public health workers and others involved in the project. Stakeholder meetings will be held to explain details and aims of the project and address any questions and concerns.
“The goal is to both understand community perceptions and to help the community decide any changes or improvements that may need to happen to control the larvae,” Ajibade says. “It’s important to ensure that we have community buy-in in order for the project to be sustainable in the long run.”
Ajibade, a native of Lagos, Nigeria, feels a personal connection to the project. She suffered a near-fatal bout of malaria while in high school and lost a childhood friend and several neighbors to the disease.
“I was incredibly ill,” Ajibade recalls of her malaria experience. “In that moment, I said to myself, ‘I can’t die now. I have so many dreams I want to achieve.’ I’m one of the lucky ones who survived. I want to help a lot of other children out there with dreams and goals to survive.”
The project will include testing of the effectiveness of using remote-sensing technology to target and treat stephensi larvae during the dry season. Randomized trials will determine the method’s impact on stephensi persistence, abundance and rate of malaria infections.
“If our method works, we hope to create a platform for an approach that could be scaled up to the national level in Ethiopia and applied in other countries in Africa,” Vazquez-Prokopec says.
“If we are able to control this mosquito at the right time in the right places we may even have a chance of eliminating it in Ethiopia and some other countries where it is invasive.”
Story by Carol Clark. Photos by Kim Awbrey, except where noted.
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