The slowdown in global warming observed at the end of the last century resulted in a decrease in malaria transmission in the Ethiopian highlands, according to a study led by the Barcelona Institute for Global Health. The Barcelona Global results. and health.
There has long been a heated debate about the impact of global warming on the incidence of malaria. It is believed that one of the regions where the greatest effect could be seen is in the highlands, where lower temperatures limit the abundance of the vector, leading to intermittent, seasonal outbreaks of the disease.
“We see that the epidemiology of malaria in these areas is strongly governed by climatic control, which manifests itself at all scales (months, years, and even decades), which makes the epidemiology of malaria in these areas strongly governed by climatic control, which manifests itself at all scales (months, years, and even decades), which is strongly not affecting malaria dynamics in Africa”, explains Xavier Rodó, director of the Climate and Health program at ISGlobal, a center supported by the “la Caixa” Foundation and the University of Chicago, and first author of the study now published in the journal Nature Communications.
At the end of the 20th century, a clear decrease in the incidence of malaria was observed in East Africa. This could simply be the result of increased control measures against the disease, or it could be due to an increase in the average global surface temperature of the Earth’s surface, a phenomenon that was observed between 1998 and 2005.
To answer this question, Rodó and his colleagues focused on the Oromia region of Ethiopia, a densely populated high plateau located between 1,600 and 2,500 meters altitude. This region has the advantage of having very complete records of annual malaria cases for both parasites (P. falciparum and P. vivax) between 1968 and 2007, while public health interventions to control the disease were not strengthened in the region until 2004. This allows us to separate the effect of climate from the effect of control measures on parasites that respond differently to climate.
How climate change impacted
Using a mathematical model, the team analyzed the relationship between malaria cases, regional climate (local temperatures and precipitation) and global climate (in particular from the Pacific Ocean due to the effect of El Niño and the so-called Pacific Decadal Oscillation).
The results show that the variation in malaria cases for both parasites correlates extremely well with changes in regional temperatures: the decrease in temperatures in the region linked to the effect of climate change coincided with the reduction in malaria cases that occurred in 2000, from years before disease control measures were strengthened.
The connection between disease dynamics and climatic conditions is so close that it is observed on different time scales: from seasonal to multi-year and even decadal cycles. – Mercedes Pascual
These in turn coincided with the momentary slowing of the increase in global mean surface temperature due to the effect of the El Niño phenomenon and the Pacific decadal oscillation. The analysis also shows that there is a “cascade of effects” between global climate variability, the El Niño-Pacific Ocean temperature) and regional temperature variation in East Africa, which ultimately translates into new cases of malaria in the Ethiopian highlands.
” The connection between disease dynamics and climatic conditions is so close that it is observed on different time scales: from seasonal to multi-year and even decadal cycles. The incidence of c maljó tempera alone reflects in we had already demonstrated, but also the decline in warming that was observed at the beginning of the century, the focus of this study,” says Mercedes Pascual, a researcher at the University of Chicago and last author of the study.
For Rodó, “the evidence that the period of slowing global warming had an impact on malaria transmission demonstrates the strong link between climate and health”. These results also indicate that climate conditions should be taken into account and integrated into early warning systems at the time of public evaluations to control the disease.