Climate change likely to increase cases of malaria and dengue

Global warming may not only significantly increase and intensify extreme weather events, it could also impact upon the extent and frequency of mosquito-borne diseases such as malaria and dengue, almost doubling the number of people affected.

A recent study conducted by the London School of Hygiene and Tropical Medicine, published in The Lancet Planetary Health Journal, indicates that by 2070 the ongoing climate crisis may put some 8 billion people at risk of being infected by malaria and dengue, an increase of 4.7 billion of those at risk compared to the period from 1970 to 1999.

The study reveals that high air temperatures will extend the malaria season by an additional 1.6 months in the tropical highlands of Africa, the Eastern Mediterranean region, and in the Americas, areas that are home to many developing countries whose health systems are weaker than those in wealthy states. The dengue season is forecast to be extended by about four months in the Western Pacific region and Eastern Mediterranean.

Scientists have also proved that the rate and frequency of both diseases will face a higher increase in those zones already affected by dengue and malaria, i.e., 20 African countries, South-East Asia, and the Americas. However, susceptibility to both diseases will be higher in densely populated zones.

“This work strongly suggests that reducing greenhouse gas emissions could prevent millions of people from contracting malaria and dengue. The results show low-emission scenarios significantly reduce the length of transmission, as well as the number of people at risk. Action to limit global temperature increases well below 2C must continue,” said Felipe J Colón-González, Assistant Professor at the London School of Hygiene and Tropical Medicine.

If the rise in temperature is not halted, policymakers anticipate the worst-case scenario which would mean that even areas that have never before experienced either malaria or dengue may become affected by these diseases.

Both malaria and dengue are transmitted by mosquitos. Every year they take the lives of hundreds of thousands of people, most of whom are children. In 2019, there were an estimated 229 million cases of malaria worldwide, according to data provided by the World Health Organization and the estimated number of deaths caused by malaria stood at 409,000 with 90% of all malaria cases being reported in Africa. Although the disease can be cured with artemisinin-based combination therapy, Oxford University has developed a vaccine that brings hope that malaria may finally be defeated.

With regard to dengue, there is a lack of effective treatment against this disease and almost half of the world’s population may be threatened by potential infection. Prior to 1970, dengue epidemics were recorded in nine countries whereas this figure stands at 100 countries today. It is estimated that every year between 100 to 400 million people are infected by the disease of whom 20,000 die.