Climate change is giving infectious disease the upper hand. Shifting weather patterns are expanding the habitats of disease carriers such as mosquitoes, bringing malaria and other serious illnesses to previously unexposed populations. Rising temperatures are also leading to increasingly frequent catastrophic weather events that create hotbeds for infectious disease and then fuel their spread further through the mass displacement of affected populations. Hotter conditions and natural disasters also accelerate the spread of drug-resistant superbugs, intensifying the fight against antimicrobial resistance. Scientists estimate that almost 60 per cent of all infectious diseases are aggravated by a hotter planet and the extreme weather events that come with it.
Many parts of the world are already experiencing the health impacts of climate change. In Africa, the arrival of the Anopheles stephensi mosquito from South Asia is causing resurgences of malaria in cities. Outbreaks of cholera are becoming more frequent as the cyclones, floods and droughts that facilitate its spread become more common. Dengue and chikungunya outbreaks are now more intense, and are spreading to new regions because of rising global temperatures. “The impact of the climate crisis is going to be counted in human lives,” says Githinji Gitahi, group CEO of Amref Health Africa.
Hope in innovation
As climate change complicates the fight against infectious diseases, scientists are finding new ammunition to treat them, and prevent them from occurring in the first place. Martin Edlund, Chief Executive of Malaria No More, an advocacy organisation, believes the eradication of malaria remains possible, despite the new challenges posed by climate change, largely thanks to the pace of innovation in the field. “There’s never been a moment of greater peril in terms of the challenges, and simultaneously greater promise in terms of the pipeline of new tools,” he says.
The world’s first malaria vaccine, RTS,S, developed by GSK and its partners for use in malaria-endemic countries, is being rolled out across more countries in sub-Saharan Africa, having already reached 2mn children in Ghana, Kenya and Malawi by the end of 2023 through the Malaria Vaccine Implementation Programme. A second vaccine was recently recommended by the World Health Organization, and dozens more are in early development. New antimalarial treatments are also under development. Beyond drugs and vaccines, scientists are finding new ways to control the disease, targeting its carriers, mosquitoes. Researchers at GSK recently discovered a naturally occurring bacterium, Delftia TC1, that could be used to stop infected mosquitoes from spreading malaria.
The fight against tuberculosis, or TB, is also showing promising progress. TB is the world’s second deadliest infectious disease after Covid-19, and climate change is making it harder to tackle, as the mass displacement of people fleeing natural disasters or unbearable climates exacerbates its spread. “There are TB drugs out there, but there is ample opportunity for improvement,” says Thomas Breuer, Chief Global Health Officer at GSK, whose scientists are among those hoping to transform how TB is prevented and treated.
Some of those potential new treatments are novel antibiotics that researchers hope will tackle multi-drug resistant strains of TB. Clinical trials are also under way for several new vaccines against tuberculosis that aim to prevent its spread (the existing vaccine protects against severe disease, but has limited impact on how it spreads). Breuer says that over half of GSK’s global health pipeline is dedicated to diseases that are affected by climate change, including new vaccines for typhoid and shigellosis. “We are essentially trying to change the trajectory of high-burden infectious diseases in lower income countries,” he says.
Building resilient health systems
Building climate resilience also means making the most effective use of existing tools. Being able to predict extreme weather events such as flooding would enable health systems to deploy oral cholera vaccines ahead of time, to ward off an outbreak. Tracking the movement of malarial mosquitoes could guide the roll-out of vaccines and other preventative measures. High-tech “biological weather stations” to remotely monitor insect species, such as those set up in Nepal by GSK, the Centre for Health and Disease Studies Nepal and Microsoft, can help prevent, plan and prepare for outbreaks of vector-borne diseases.
“That has been demonstrated by so many of the extreme weather events that become extreme health events weeks later,” says Edlund. Early warning systems needn’t all be technologically advanced. Training community health workers to report unusual cases of illness to a national surveillance system can ensure that severe public health threats are quickly quelled. An outbreak of Marburg virus in Tanzania in early 2023 was contained to nine cases thanks to speedy reporting by community health workers.
The worst health effects of climate change will strike those in the countries that are least contributing to the climate crisis, and those with the least resources to counter it. Africa is responsible for around 4 per cent of global greenhouse gas emissions, yet its vulnerability to climate-aggravated disease is far greater than the world’s highest emitters. “There will be no 96 per cent discount on the impact of global warming,” says Amref’s Gitahi.
There is cause for hope. Scientists and healthcare leaders are developing ever more sophisticated ways of countering infectious diseases with new treatments, vaccines and public health strategies. Political leaders are increasingly recognising the profound impact of climate change on human health, and the private sector, including GSK, is committed to tackling the joint challenge of climate change and infectious diseases.
Now, more than ever, it is important for those groups to work together to shape the climate-and-health policy agenda while continuing to innovate to find and scale up the tools needed to fight infectious disease on a hotter planet.
