Climate Change Could Have Direct Consequences on Malaria Transmission in Densely Populated Zones in Africa.
A study shows that the lower incidence of disease in the Ethiopian highlands at the turn of the century has a close connection with a temporary slowdown in global warming. For several years there has been a heated debate on the impact of global warming on malaria incidence. It is believed that the largest effect could occur in the highlands, where lower temperatures limit vector abundance, leading to intermittent and seasonal disease outbreaks. The decline could be simply the result of disease control measures or could reflect the temporary slowdown in increase in global mean surface temperature, a phenomenon that was observed between 1998 and 2005.
To answer this question, researchers focused on the region of Oromia in Ethiopia, a densely populated highland between 1,600 and 2,500 m above sea level. This region presents the advantage of having complete records of annual cases of malaria caused by both P. falciparum and P. vivax parasites between 1968 and 2007, and that public health interventions to control the disease were not reinforced in the region until 2004. This allowed the researchers to separate the effect of climate from the effect of disease control measures for two parasites that are known to respond differently to climate.
Using mathematical modelling, the research team analysed the association between malaria cases, regional climate (local temperatures and rainfall) and global climate. The results show that the variation in malaria cases correlates extremely well with changes in regional temperatures: the regional decline in temperatures linked to the slowdown in climate change coincided with the reduction in malaria cases observed from 2000, five years before disease control measures were reinforced.
These results also emphasise the value of considering climate conditions when evaluating public health interventions aimed at disease control, and of integrating them into early warning systems.
Reference: Rodó X, Martinez PP, Siraj A and Pascual M. Malaria trends in Ethiopian highlands track the 2000 ‘slowdown’ in global warming. Nature Communications. 10 March 2021. DOI: 10.1038/s41467-021-21815-y. https://www.nature.com/articles/s41467-021-21815-y.
Relevance to RAM: The inference is that our task to achieve malaria elimination goals will get progressively more difficult if global warming trends continue.
Photo via nature.com.