Malaria, which is World Day this Tuesday, April 25, remains a formidable disease in Africa despite the arrival of vaccines, due in particular to growing resistance to treatment, according to the World Health Organization. But not only. Weather disasters, such as Cyclone Freddy which recently hit Malawi, have sent malaria cases skyrocketing, experts warn. Indeed, increased rainfall potentially increases the number of breeding sites for mosquito vectors, such as those that transmit malaria, that breed in stagnant and temporary bodies of water.
Peter Sand, director of the Global Fund to Fight AIDS, Tuberculosis and Malaria – which provides 63% of all international funding for malaria programs – said in late 2022 that some parts of Africa that do not were not affected by malaria were now at risk, as temperatures rise and allow mosquitoes to thrive, especially at higher altitudes. However, the population of these regions will not be immunized, hence the risk of a higher mortality rate.
Researchers delved into the movements of mosquitoes in a recent study published in the journal Biology Letters that offers a glimpse of what lies ahead in the future by tracing back data from data dating back to 1898. mosquitoes that transmit malaria in sub-Saharan Africa have moved to higher altitudes by about 6.5 meters and away from the equator by 4.7 kilometers per year over the past century. A pace that matches the acceleration of climate change in these areas and may explain why malaria has spread in recent decades, the Georgetown University researchers said. The latter warn that these results have serious implications for countries that are not prepared to deal with the disease.
In Malawi, Cyclone Freddy in March – which caused the equivalent of six months of rain in the small East African country – was also behind a rise in malaria cases, says Peter Sands in a recent interview with AFP. “What we have seen in places like Pakistan or Malawi is real proof of the impact climate change is having on malaria,” he said in a recent interview with AFP. “You have these extreme weather events, whether it’s floods in Pakistan or a cyclone in Malawi, after which a lot of water sits there.” “We have seen a very marked increase in malaria infections and deaths in both cases,” he said on World Malaria Day, April 25, which usually “celebrates the progress we’ve made.” But this year, “we have to ring the alarm bells,” he says. If malaria gets worse due to climate change, action must be taken now to roll back (the disease) and eliminate it.” In Pakistan as in Malawi, the pools of water left after the water recedes are an ideal breeding ground for mosquitoes carrying the disease.
However, while the impact of climate change on mosquitoes is quite clear, its impact on malaria transmission is not yet sufficiently documented.
Peter Sands underlines that there has been progress in the fight against malaria but recalls that a child dies of the disease every minute. In 2021, the WHO estimated the number of cases worldwide at 247 million (up from the previous year (245 million). Some 619,000 people died of malaria that year.
The vast majority of cases (95%) and deaths (96%) occur in Africa: this region continues to “bear a large and disproportionate share of the global burden of malaria”, laments the WHO. More than half of all malaria deaths worldwide are concentrated in four African countries: Nigeria (31.3%), Democratic Republic of Congo (12.6%), Tanzania (4.1%) and Niger (3.9%). The most numerous victims are among children under five: in Africa this category accounts for 80% of deaths.
The appearance in Africa of a new mosquito, Anopheles stephensi, from Asia and the Arabian Peninsula, poses an additional threat to the fight against malaria in Africa. This insect, now present in Sudan, Ethiopia, Somalia and Nigeria, is adapted to the urban environment and is resistant to many of the insecticides currently used. However, the use of mosquito nets impregnated with insecticides was until now the main mode of preventive control against the disease. By 2030, the WHO hopes to reduce malaria mortality by at least 90%. Since 2015, around ten countries have been officially declared malaria-free, including Argentina (in 2019), Algeria (2019) and China (2021).
In this wake, last year more than a million children in Ghana, Kenya and Malawi received a first malaria vaccine, RTS,S, developed by British pharmaceutical giant GSK.
Another vaccine, R21/Matrix-M, developed by scientists at the University of Oxford, received the green light from the Ghanaian authorities in mid-April to be used in this country, a first for this vaccine which is generating a lot of hope.
But for Peter Sands, vaccines are not “a magic bullet”, not least because of their cost and the difficulty of large-scale deployment.
The people most vulnerable to malaria are children under five and pregnant women. Deaths are largely due to late diagnosis and treatment. “It’s mostly about having the infrastructure to diagnose and provide treatment […] which means you need health workers in every village who have the tools to test and treat the disease,” Sands said. .
According to him, the countries most threatened by climate change are also those that suffer the most from malaria, with fragile infrastructures that can be easily destroyed during natural disasters. “We are therefore very concerned that the countries in which malaria is most prevalent are also those most at risk of being affected by extreme weather events caused by climate change,” insists Peter Sands.
