Health workers in Pakistan then spoke of clouds of mosquitoes “so thick that you could barely see through them.” It happened in 2022, with the floods that the country suffered after an extreme heat wave that brought more intense than usual Amazon rains and the melting of the Himalayan glaciers. Among many other misfortunes, that downpour produced a massive increase in malaria cases in the country: from 400,000 cases to more than 1.6 million.
This case once again highlighted that climate change has profound implications for ecosystems and biodiversity, but also for human health. And that among the health threats exacerbated by this climate crisis, the expansion and increase of vector-borne diseases, such as malaria, represent one of the most significant challenges to global public health.
Malaria is a disease caused by parasites and transmitted to humans through the bite of mosquitoes that has been a serious health problem for centuries... and continues to be so: today, in the world, one child under 5 years of age dies every minute due to this disease that, last year alone, caused more than 600,000 deaths, especially in the African region, which is home to 94% of the cases.
The fight against malaria and its uncertain end as a public health problem in 2030 faces great challenges: international financing has been stagnant since 2015, there is still no effective vaccine, mosquitoes are generating resistance to insecticides and people to antibiotics. And, meanwhile, climate change is expanding the seasons and territories reached by mosquitoes.
Global warming accelerated by human activity - CO2 emissions have increased by 50% in the last sixty years - is facilitating the expansion of mosquitoes into areas and habitats that were previously inhospitable due to their low temperatures, but which are increasingly more suitable.
This includes the rise of these insects to more mountainous regions and their expansion to higher latitudes on the planet, putting populations and communities that have not historically been exposed at risk of infection. It was also the case with the Pakistan floods: there was a higher proportion of cases coming from mosquitoes carrying the deadliest species of the disease, typically found in Africa rather than Asia.
Furthermore, risk seasons are lengthened in places where the mosquito is already present. Comparing measurements from the 1950s to those from the last decade (2012-2021), rising temperatures have caused an increase in the length of the malaria transmission season of 31.3% on land. highlands of the Americas and 13.8% in the highlands of Africa, according to The Lancet Countdown report for 2022.
Extreme weather events such as heat waves or floods are becoming more frequent, and they also have a huge impact on disease transmission. Heavy rains and stagnant flood waters create more breeding habitats for these insects. But in addition, variations in rainfall and temperature patterns affect the survival and reproduction of mosquitoes and the life cycle of the malaria parasite.
Periods of intense heat can accelerate the maturation of the parasite inside the mosquito, reducing the time needed for it to become infective; while prolonged droughts can concentrate human and mosquito activity around limited water sources, increasing transmission rates.
The increase in the incidence and distribution of malaria is notable, and very worrying. Between 2019 and 2022, cases increased from 231 to 249 million. And it's getting worse: the WHO estimates that by 2030 there will be 250,000 additional deaths annually attributed to climate change alone and caused by malaria, diarrhea, malnutrition and heat.
Multilateral health organizations such as the Global Fund to fight AIDS, Tuberculosis and Malaria - responsible for channeling and providing 65% of international financing against malaria - have begun to incorporate climate change into their work strategies and policies. . In fact, over the next three years, this organization, which is the largest international piggy bank that exists against these pandemics, will allocate 70% of its financing - about $9 billion - to the 50 countries most vulnerable to the climate.
However, each year the gap between existing resources and those needed to end malaria as a public health problem widens. In 2022, global funding reached $4.1 billion, a far cry from the almost $8 billion that the WHO says is needed annually. Furthermore, climate financing focused on health is still very insufficient: between 2018 and 2020, only 0.3% - $14 million - of multilateral financing for climate change adaptation was allocated specifically to the health sector. The efforts that must be made are notable, even more so, if possible, with the growing threat of climate change, declared by the WHO as one of the greatest health threats facing humanity.
*Pablo Trillo is a journalist at Salud por Derecho.
