According to the World Health Organization (WHO), climate change is driving the rapid spread of diseases caused by mosquito-borne arboviruses, including dengue, chikungunya, and zika. Experts from the WHO warned that global outbreaks of these diseases could be looming as climate change facilitates the expansion of the mosquito vectors, particularly the Aedes aegypti mosquito, into new territories.
Raman Velayudhan coordinates WHO’s dengue and arbovirus initiative, emphasized the role of climate change in the spread of these diseases. He stated that “climate change has played a key role in facilitating the spread of the vector mosquitoes.” As the planet warms, mosquitoes are moving into new areas and thriving in environments where they were previously not found.
Currently, 129 countries are at risk from dengue, with 100 countries already facing endemic transmission of the disease. The number of dengue cases has increased exponentially in recent years, from around half a million cases in 2000 to approximately 5.4 million cases in 2019, the worst year on record, according to Velayudhan. Although the number of cases was not properly recorded during the COVID-19 pandemic, he warned that the numbers remained high.
In addition to dengue, chikungunya is also experiencing a dramatic surge, particularly in the Americas. Diana Rojas Alvarez, WHO’s technical lead on chikungunya and zika, stated that around 135,000 cases of chikungunya have been reported in the USA so far this year, compared to 50,000 cases reported during the first half of 2022. The geographic spread of both diseases is also expanding, with cases being reported further south in the Americas and moving into the northern hemisphere, including some European countries.
Rojas Alvarez described the situation as “alarming,” as the mosquitoes and these diseases are increasing in altitude and latitude due to climate change. She warned that the high transmission rates of dengue and chikungunya in the Americas could be indicative of what the upcoming summer season in the northern hemisphere may entail. Both dengue and chikungunya often cause mild symptoms such as fever, body ache, and rash. However, a significant percentage of people who contract chikungunya may experience symptoms for months or even years, with long-term disability being a possibility.
According to Velayudhan, people who are reinfected with a different serotype of dengue, which has four closely related serotypes, may experience severe disease, including organ failure and even death. He highlighted that this is a significant threat to the world, as most countries now have all four serotypes of dengue in circulation. Therefore, it is crucial for countries to prioritize mosquito control measures and be vigilant in detecting and responding to the spread of these diseases.
The WHO experts called for urgent action to rein in the spread of the mosquito vectors and prevent major outbreaks of these diseases. They emphasized the need for increased mosquito control measures, including reducing breeding sites, using insecticides, and implementing community-based interventions. In addition, early detection and monitoring of cases, as well as public awareness and education campaigns, are essential to prevent the spread of these diseases.
Furthermore, addressing climate change and its impact on disease transmission is critical in the long term. Climate change contributes to the expansion of mosquito habitats and the increase in mosquito populations, as higher temperatures and altered rainfall patterns create favorable conditions for their survival and reproduction. Climate change also affects human behavior, such as changes in migration patterns and urbanization, which can impact disease transmission dynamics.
Efforts to combat climate change, such as reducing greenhouse gas emissions, promoting sustainable development, and implementing climate resilience strategies, can have a positive impact on reducing the spread of mosquito-borne arboviruses. This includes transitioning to renewable energy sources, protecting and restoring natural ecosystems that act as buffers against disease vectors, improving urban planning to reduce mosquito breeding sites, and promoting climate-smart agriculture practices.
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International collaboration and coordination among countries, as well as engagement with local communities, are crucial in addressing the spread of mosquito-borne diseases in the context of climate change. This includes sharing best practices, data, and information on disease surveillance and response, as well as fostering community participation in vector control efforts and health promotion campaigns.
