DAKAR, SENEGAL —
From deadly droughts and destroyed crops to shrinking water sources, communities across sub-Saharan Africa are struggling to withstand the onslaught of global record-breaking temperatures.
But the dangers do not end there. Rising heat poses another threat, one that is far less known and studied but could spark disease epidemics across the continent, scientists say.
Mosquitoes are the menace, and the risk goes beyond malaria.
The Aedes aegypti mosquito, which spreads debilitating and potentially deadly viruses, from Zika and dengue to chikungunya, thrives in warmer climates than its malaria-carrying cousin, known as Anopheles, say researchers at Stanford University.
In sub-Saharan Africa, this means malaria rates could rise in cooler areas as they heat up, but fall in hotter places that now battle the disease. In those areas, malaria, one of the continent’s biggest killers, may be rivaled by other vector-borne diseases as major health crises.
“As temperatures go past 25 degrees Celsius (77 degrees Fahrenheit), you move away from the peak transmission window for malaria, and towards that of diseases such as dengue,” said Erin Mordecai, an assistant professor at Stanford.
“We have this intriguing prospect of the threat of malaria declining in Africa, while Zika, dengue and chikungunya become more of a danger,” she said.
Besides a warming planet, scientists fear growing urbanization across Africa could also fuel the transmission of diseases carried by the Aedes aegypti mosquito, which flourishes in cities and slums, the opposite of the country-loving Anopheles.
Half of Africans are expected to live in cities by 2030, up from 36 percent in 2010, according to World Bank data.
A soaring number may become prey to vector-borne viruses like dengue, which have struck Africa at a record pace in recent years, fuelled by urbanization, population growth, poor sanitation and global warming, the World Health Organization (WHO) says.
“We see poorly planned development in Africa, not just with megacities but smaller settlements ... which often lack proper water and sanitation,” said Marianne Comparet, director of the International Society for Neglected Tropical Diseases.
“Climate change, disease and the interaction between man and habitat — it is a crisis going under the radar ... a time bomb for public health problems,” she added.