Mosquitoes are migrating and that could mean more malaria
Anopheles mosquito. It is the main main vector for malaria. Africa bears nearly the entire global burden of malaria, accounting for an estimated 96 per cent of malaria cases and deaths in 2020.
What you need to know:
- The temperature ranges where malaria-carrying mosquitoes thrive in the region are rising in elevation due climate change.
- As it gets warmer at higher altitudes with climate change and all other environmental changes, mosquitoes are adapting and can survive higher up the mountain.
Scientists are worried that people living in areas once inhospitable to mosquitoes in Eastern Africa countries such as Kenya, Tanzania and Ethiopia could be newly exposed to malaria.
This is after they found evidence showing that the temperature ranges where malaria-carrying mosquitoes thrive in the region are rising in elevation due climate change.
According to Manisha Kulkarni, a professor and researcher studying malaria in sub-Saharan Africa at the University of Ottawa, as it gets warmer at higher altitudes with climate change and all other environmental changes, mosquitoes are adapting and can survive higher up the mountain.
The researchers found that the habitat for malaria-carrying mosquitoes had expanded in the high-elevation Mt Kilimanjaro region by hundreds of square kilometers in just 10 years as lower altitudes become too hot for the bugs.
They further noted that the region, which is growing in population, is close to the border of Tanzania and Kenya, two countries that in 2021 accounted for six per cent of global malaria deaths.
This comes at a time when malaria cases remain high in Africa, where children under five years account for 80 per cent of all malaria deaths.
In February this year, Gavi, the Vaccine Alliance, while highlighting a peer reviewed study published by Biology Letters, which analysed data for 22 species of Anopheles mosquitoes in Africa from 1898 to 2016, disclosed that new data showed mosquitoes have been able to move away from the equator and into higher elevations, spelling trouble for the spread of infectious disease.
“Climate change has long been predicted to shift the habitat ranges of animals and plants, and when this includes insects like mosquitoes, it can mean fueling the spread of deadly infectious diseases.
“Newly analysed historical data shows what we feared could happen is already underway – mosquitoes that spread malaria have elevated their range by about 6.5m per year and away from the Equator by 4.7km every year for the past century,” Gavi said while explaining that this would allow them to take over regions utterly unprepared to deal with a disease that kills more than 600,000 people every year, many of them children under five.
The study’s lead author Colin Carlson, a biologist at Georgetown University’s Center for Global Health Science and Security, pointed out that so far, modelling predictions have been for a hotter planet in the future, rather than an analysis of present-day shifts in habitat.
“Until now, there has not been a ton of indication that these mosquitoes were already on the move. There’ve been dozens of studies predicting that they should start moving in response to climate change, but – as with a lot of things in climate and health work – we had a clearer picture of what the future might look like than what was already happening around us,” he said.
This is why Gavi highlights that since industrial revolution, the earth has already warmed by around 1.2°C.
“This shift in insect range could explain the incursion of malaria transmission into new areas such as highland East Africa over the past few decades. It has been accompanied by global expansions in the range of the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus) that spreads chikungunya,” the experts warn.
“Similarly, the North American vector of Lyme disease, the deer tick Ixodes scapularis, has spread over 40km per year.”
According to the World Health Organisation in its 2021 World Malaria Report, which was released last year, the number of deaths arising from malaria in Kenya increased from 11,768 in 2020 to 12,011 in 2021.
The WHO observed that in 2020, malaria in the country accounted for 2 per cent of deaths, and this decreased to 1.9 per cent in 2021.
This is after the number of malaria cases in the country rose from 3.3 million in 2020 to 3.42 million in 2021.
The findings further disclosed that in 2020 malaria in the country accounted for 1.1 per cent of all malaria cases across the globe, increasing to 1.3 per cent in 2021.
