Climate change is leading to new cases of malaria, complicating efforts to combat the disease
There were an estimated 249 million cases of malaria worldwide last year, the World Health Organization said Thursday, significantly more than before the Covid-19 pandemic and an increase of five million from 2021. Malaria remains one of the biggest killers of children.
Those new cases were concentrated in just five countries: Pakistan, Nigeria, Uganda, Ethiopia and Papua New Guinea. In three of these cases, climate change directly contributed, says Dr. Daniel Ngamije, who heads the WHO’s malaria program.
In July 2022, massive floods left more than a third of Pakistan underwater, displacing 33 million people. An explosion of mosquitoes soon followed. The country reported 3.1 million confirmed cases of malaria that year, compared to 275,000 the year before, with a fivefold increase in the transmission rate.
“With the very heavy monsoons, we expected these impacts, but not on this scale,” said Dr. Muhammad Mukhtar, director of Pakistan’s National Malaria Control Program.
While flood waters have receded in some areas, large areas of standing water still remain, and the malaria parasite is now well established and circulating in communities that previously had little immunity, said Dr. Mukhtar.
More than seven million mosquito nets have been distributed to displaced people, but people living in small tents or in large, crowded halls have nowhere to hang them, Dr. Mukhtar said. The country relies on spraying insecticides to control mosquitoes and the mass administration of antimalarial drugs.
Pakistan has confirmed 2.3 million malaria cases so far this year and expects the total to exceed even the total from 2022.
“It will take another one to two years for the situation to return to normal, if God forbid another natural disaster does not occur,” said Dr. Mukhtar.
In Pakistan, as in other places where weather conditions caused the spread of malaria, the new mosquito habitat was only part of the problem. The floods damaged 2,200 health care facilities, leaving millions of people in the affected districts without access to treatment.
The number of deaths from malaria worldwide remained largely stable between 2021 and 2022, but at an estimated 608,000 was still significantly higher than the total of 576,000 in 2019, before the pandemic.
Deaths had fallen steadily between 2000 and 2015 due to a widespread push to create better diagnostics and treatments, as well as insecticide-treated bed nets, which were widely available in the malaria areas of sub-Saharan Africa. But growing resistance to those drugs and insecticides, plus stagnant funding and changes in mosquito behavior, together we have brought that progress to a standstill. Covid has further disrupted both healthcare and supply chains.
The changing climate was also at least partly responsible for a rise in malaria cases in Ethiopia (by 1.3 million more cases than the year before) and Uganda (by 600,000 more), said Dr. Ngamije of the WHO. Highlands that had long been too cool and dry to support malaria mosquito breeding are starting to report cases in those two countries.
In Ethiopia, major civil conflicts that have displaced millions of people have also made them vulnerable to malaria again. Conflicts have also caused the spread of malaria in other areas: in Myanmar, for example, cases have increased more than sevenfold.
And Ethiopia is one of the African countries where an invasive mosquito species, Anopheles stephensithat thrives in urban areas once largely free of malaria is now spreading the disease.
There are also worrying signals in Uganda the malaria parasite becomes resistant to the main drug used to treat the disease.
Nigeria, the country with the highest malaria burden, also experienced extreme flooding in 2022. The country managed to keep the number of new infections stable, but rapid population growth added another 1.3 million cases.
Climate change is also driving malaria cases with people displaced by drought, heat waves and storms, leaving them in substandard housing, said Dr. Ngamije. Weather disasters disrupt supply chains of malaria tests, treatments and insecticides. Food insecurity, which is increasing in sub-Saharan Africa due to floods and droughts, means that more and more children are malnourished and therefore more susceptible to severe malaria. Repeated malaria infections keep children out of school and destroy the savings of the lowest-income families in affected countries.
The malaria report did contain good news. Azerbaijan, Belize and Tajikistan have all been declared malaria-free by the WHO in 2022.
More than two million children in Ghana, Kenya and Malawi had received at least one dose of a new malaria vaccine by the end of 2022. Vaccination coverage will be expanded to a further twelve countries next year. There has been a 13 percent decrease in infant mortality for four years in the areas where the first malaria vaccine was administered.
Dr. Ngamije said he had hoped the 2022 malaria data would show global cases would fall rather than rise. But the WHO’s approval of a second malaria vaccine that will rapidly increase supply, plus the growing availability of bed nets treated with multiple types of chemicals to counter the effect of insecticide resistance, make him optimistic that significant progress will be made next year will be booked.
“If it turns out to be a normal year,” he said.