An article published in Lancet Planetary Health warns that a warming climate could bring about a public health disaster in Sub-Saharan Africa in terms of changing mosquito-borne diseases; and, experts in Europe are growing concerned over the possibility of increasing tropical disease cases brought about by growing numbers of tiger mosquitoes.
Professor Jan Semenza, who leads a European Centres for Disease Control (ECDC) section assessing infectious disease threats across Europe, said: “We have seen an increase in vector capacity due to climate change … Dengue has a huge disease burden worldwide. It can morph into a life-threatening condition, so we are concerned about it moving into Europe.”
A changing risk landscape for travellers
Malaria, spread by the nighttime-biting Anopheles gambiae, affects more than 200 million people in Sub-Saharan Africa, and public health authorities have developed advanced strategies to help control its spread. A different mosquito, however, spreads Rift Valley Fever, yellow fever, Zika, chikungunya and dengue in Africa, and this daytime-biting Aedes aegypti mosquito is not affected by those strategies in place that help stop the spread of malaria.
In Europe, it is the Aedes albopictus mosquito – also known as the tiger mosquito – native to Southeast Asia that is threatening the spread of tropical diseases there; and, much like Africa’s Aedes aegypti mosquito, the tiger mosquito prefers warmer climates and human-made habitats for breeding.
A close proximity to populous areas – with a high footfall of both locals and travellers – could drastically increasing the instance of human transmission, and so the travel health risk of these areas will need to be reassessed. For example, Kenya and Uganda – both popular tourist destinations in Africa – are likely to become high-risk zones for the transmission of both malaria and dengue by 2050, as temperatures rise, according to the Lancet article. “Climate change is going to rearrange the landscape of infectious disease,” warned Erin Mordecai, Stanford biologist and lead author of the Africa-focused study.
Sustainable tourism can help prevent the spread of tropical diseases
Dr Jérémy Bouyer, a biologist and mosquito expert at the French Agricultural Research Centre for International Development (CIRAD), who predicts that Europe could face an uncontrolled dengue epidemic within the next five to ten years unless more is done to control mosquito populations, is working to develop a kind of insect birth control that will eventually deplete the number of disease-carrying tiger mosquitoes. Meanwhile, over in Indonesia, trials of a naturally occurring bacterium called Wolbachia, which blocks dengue virus replication in the mosquito and prevents transmission, was found to reduce dengue cases.
However, both Bouyer and the Stanford study concede that reducing the amount of discarded rubbish items such as plastic, which provides perfect water-catching breeding grounds for the Aedes larvae, will be a crucial step towards helping prevent the spread of these diseases. It seems that sustainable tourism has an intergral role to play in preventing the spread of mosquito-borne diseases.