The impacts of the climate crisis, from devastating wildfires across Canada, Greece and Hawaii, to flooding and landslides in India and Libya, are clear to see. But there are also unseen effects of climate change that are increasingly posing risks to our health.
Rising global temperatures, changing rainfall patterns and other extreme weather conditions bring to the fore climate-related health concerns that demand new solutions. The threats of vector-borne diseases, which are transmitted to humans by other organisms like mosquitoes or ticks, are being exacerbated by climate change.
To put this in perspective, by 2080, climate change and increasingly urbanised societies could cause six billion people worldwide to be at risk of dengue fever, which is spread by mosquitoes. But climate change is also impacting the spread of dengue now. In 2022, Brazil recorded 2.3 million cases of dengue and almost 1,000 deaths from the disease, during the largest dengue outbreak in the country on record.
Over the next century, vector-borne diseases are projected to increase across more temperate parts of the world as they become warmer and wetter. The locations at risk of being affected include northeastern USA, the highlands of Central America, the Andean region of South America, eastern South America, the horn of Africa, South Africa, Madagascar, eastern Australia, and parts of Indonesia and East Asia, and even some parts of Europe. While the types of mosquitoes that spread these diseases are currently less common in these locations, the population at risk of these diseases will increase by as much as 4.7 billion by 2070.
However, these diseases could decrease in frequency in areas where disease-carrying mosquitoes are currently more common. These include places like the northern half of South America, sub-Saharan Africa, the Indian subcontinent, southeast Asia, and northern Australia.
Under all potential climate models – from worst-case to best-case scenarios – the picture over the coming decades will change. People who have not yet come across disease-carrying mosquitoes might soon need to think about how to protect themselves. This is a growing problem of global concern, which does not differentiate between more- and less-developed countries.
Currently, there are two vaccines approved to protect against dengue fever, one in the US and one in Europe, and several more in development. However, there are currently no approved therapeutic drugs for dengue.
Mosquito control has historically been the main tool to limit the spread of dengue, including fogging streets and homes with insecticides, using mosquito traps, repellents, nets and introducing predators which eat the larvae. However, with the climate-driven expansion of mosquitoes' range, emerging resistance to insecticides, and rapid urbanisation, new tools are needed to control the outbreaks of mosquito-borne diseases, like dengue and other arboviruses.
