Climate change drives malaria transmission in Africa, study shows

March 10 (UPI) -- The brief global warming slowdown measured at the end of last century hastened a decline in malaria transmission across the Ethiopian highlands, according to a new study published Wednesday in the journal Nature Communications.

The findings could help settle the ongoing debate over the influence of climate change on malaria transmission.


Scientists have previously hypothesized that cooler temperatures across the highlands of East Africa have helped limit the abundance of malaria-carrying mosquitoes, yielding only periodic and seasonal disease outbreaks.

"We see that malaria epidemiology in these areas is strongly under climate control at all scales -- months, years and even decades -- which settles once and for all the debate on whether climate change is affecting or not the dynamics of malaria in Africa," first author Xavier Rodó, bead of the climate and health program at the Barcelona Institute for Global Health, said in a news release.

The slowdown in global warming, observed between 1998 and 2005, offered scientists a chance to test this hypothesis.

Scientists analyzed changes in the number of malaria infections -- caused by both P. falciparum and P. vivax parasites -- recorded in the Ethiopian region of Oromia between 1968 and 2005. Oromia is a densely populate region of the Ethiopian Highlands located between 1,600 and 2,500 meters above sea level.


Using sophisticated statistical models, researchers teased out the relationship between malaria incidence and both regional climate conditions, local temperatures and precipitation, and global climate patterns, such as El Niño and the Pacific Decadal Oscillation on the Pacific Ocean.

The analysis showed infection rates are strongly correlated with local temperature changes.

The data confirmed malaria cases begin declining shortly after the warming slowdown measured at the end of last century, before authorities redoubled malaria control measures.

The warming slowdown and decline in malaria cases across Oromia coincided with El Niño and the Pacific Decadal Oscillation, highlighting the links between global and regional climate trends -- and their effects on disease vectors.

"The coupling between disease dynamics and climate conditions is so strong that it is evident at multiple temporal scales, from seasonality to multi-annual cycles to decadal trends," said co-author Mercedes Pascual, researcher at the University of Chicago.

"Malaria incidence not only tracked changes in temperature, which we had demonstrated before, but also in the decrease at the turn of the century, the focus of this work," said Pascual.

Researchers suggest public health officials and policy makers must account for the influence of climate change when preparing for outbreaks and planning disease mitigation efforts.


Previous studies have shown that the effects of climate on mosquito-borne diseases are unlikely to be uniform.

In different parts of the world, arming trends are expected to benefit certain mosquito species while inhibiting others. But while nuance is expected, researchers predict that warming, on the whole, will accelerate the transmission rates of a number of debilitating diseases, including yellow fever, Zika, chikungunya and dengue fever.

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