OBUASI, Ghana — Despite being one of the oldest diseases in the world, malaria also remains one of the deadliest, killing 400,000 people — mostly children — every year. That is fueled in part by its ability to develop resistance to man-made drugs and insecticides, even as health experts continue the search for new tools.
Now, another threat is emerging: changing weather patterns linked to climate change, which the World Health Organization estimates will lead to at least 60,000 more deaths from malaria between 2030 and 2050.
The evidence base to study the links between antimalarials and long-term health outcomes is thin, according to a recent report. Peace Corps volunteers might offer one avenue for better research.
In late February, communities living in the gold mining district of Obuasi, Ghana, were already starting to feel the impact, with late rains and unseasonably high temperatures creating a perfect breeding ground for mosquitoes. As residents waited in vain for the rains to start, fumigators arrived to rid their homes of the mosquitoes that had begun to appear earlier and in higher numbers than usual.
The mosquitoes normally come out in late March, by which time people’s homes have been sprayed with a long-lasting insecticide, said Samuel Asiedu, director of AGAMal, a company that has been doing indoor residual spraying in Obuasi since 2006 with an impressive track record of results.
This year, however, AGAMal has been forced to change its approach, including forking out $25,000 to fumigate the Obuasi houses just to keep the mosquitoes at bay before the indoor residual spraying program kicks off. “If we had waited … the mosquitoes would have had a field day,” Asiedu said.
A new threat
There have been decades of progress in the fight against malaria, with the emergence of a number of effective prevention and treatment tools, including a new vaccine currently undergoing a pilot. But worryingly, malaria cases started to rise in 2015 in Africa’s 10 highest-burden countries, as well as in parts of Latin America. The government of Burundi declared an epidemic in 2017 after seeing an uptick in cases.
The resurgence is partly explained by mosquitoes’ and the malaria parasites’ increased resistance to insecticides and antimalarial drugs. In Venezuela, the outbreak has been linked to illegal mining activities and deforestation. However, some — including Burundi’s WHO representative — view climate change as a growing issue.
Vector-borne diseases such as malaria and dengue are strongly influenced by climate. “Variation in climatic conditions, such as temperature, rainfall patterns, and humidity, impact the abundance and longevity of the mosquito, the development of malaria parasites in the mosquito, and, subsequently, malaria transmission,” said Rachel Lowe, associate professor at the London School of Hygiene & Tropical Medicine.
Such changes could see malaria transmission increase in areas where the disease is already present, but it could also spread to places that have historically been malaria-free. Cooler areas, such as highlands in Africa, may end up with more mosquitoes as temperatures rise, which could be deadly for communities that are unlikely to have developed a natural immunity to malaria. Parts of sub-Saharan Africa, South America, and China could see a 50% increase in transmission, according to a report from the World Bank.
The rising frequency of extreme weather events, especially cyclones and floods, could also heighten the risks. Increased quantities of standing water are ideal for mosquito breeding, while higher levels of displacement and migration can interrupt anti-malaria efforts, stretch health systems, and potentially bring malaria into new areas.
However, the link between weather and malaria is not straightforward. Predicting malaria incidence is complex and involves a number of factors, such as drug and insecticide resistance, changes in land use, migration, and human behavior, all of which will be changing at different speeds, according to Chris Drakeley, a professor at LSHTM.
Furthermore, while climate change may cause malaria rates to rise in some areas, they could also go down in others. Parts of West Africa are predicted to become hotter and drier, for example — conditions that mosquitoes find it harder to survive in.
In response to these concerns, some countries, including South Africa, India, and Botswana, have been testing weather data modeling to predict malaria outbreaks, with some success. However, most early warning systems for malaria have been hindered by a lack of reliable data, surveillance capabilities, and high-quality climate forecasts, scientists say.
In February, advocacy group Malaria No More U.S. announced a new program to develop a similar approach to help fight mosquito-borne diseases using weather data from IBM’s The Weather Company, as well as health and population information. The program will include producing heat maps and dashboards to inform efforts to predict and control mosquito-borne diseases — allowing governments to prioritize interventions where they’re needed most.
The hope is that the program can test how weather data could be used to accelerate progress against malaria. “By integrating weather and disease risk data, the ... initiative will equip governments and partners to more precisely target and time health interventions to better protect the most vulnerable populations,” said Martin Edlund, CEO of Malaria No More U.S.
Editor’s Note: Malaria No More U.K. supported the author’s travel for this reporting. Devex retains full editorial control of the content.