Milad Zandi, PhD, on rising temperatures and the spread of mosquito-borne diseases like dengue, Zika, and chikungunya, increasing the risk of outbreaks in tropical and temperate regions.
Image credits: CDC
Climate change is increasingly recognized as a factor in the spread of arboviruses, diseases transmitted by mosquitoes and ticks. Viruses such as dengue, Zika, chikungunya, and West Nile are directly influenced by environmental factors like temperature, humidity, and precipitation patterns. As global temperatures rise, the range of mosquito vectors like Aedes aegypti and Aedes albopictus, which carry these viruses, has expanded into previously cooler regions, heightening the risk of outbreaks in areas where these diseases were once rare.1
Rising temperatures shorten the incubation period of viruses within mosquitoes, accelerating viral replication and increasing transmission rates. Studies have shown that higher temperatures significantly reduce the extrinsic incubation period (EIP) for diseases like dengue, thus enhancing transmission.1
Another recent study estimated that climate change accounts for 19% of the global rise in dengue cases, with temperatures increasing the speed of mosquito virus transmission. This research, covering 21 dengue-endemic countries, predicts a 40%-60% rise in global cases by 2050, with some regions such as parts of Peru, Mexico, and Brazil, facing increases of up to 150%-200%.2
As of 2024, there have been a total of 8,064 reported dengue cases in the United States. This data includes cases from both US states and territories, with reports from 52 jurisdictions. The numbers are provisional and may be subject to change due to delays in reporting. Most cases in the US are linked to travel-related infections, although some local transmission has also been reported. Most are in warmer southern states such as Florida, Texas, Arizona, and Southern California.3
Milad Zandi, PhD
Image credits: LinkedIn
In an exclusive email interview with expert virologist Milad Zandi, PhD emphasized, "The warmer the climate, the faster the virus replicates within the mosquito, increasing the chances of transmission." Climate-induced changes in rainfall patterns also create ideal breeding grounds for mosquitoes, while drought conditions can exacerbate breeding in stored water containers. These environmental shifts have already been linked to major dengue outbreaks in Southeast Asia and South America, often exacerbated by the El Niño phenomenon.
Urbanization, often driven by climate change, further contributes to the spread of arboviruses. Informal settlements in low- and middle-income countries, where waste management and water systems are poor, provide abundant mosquito breeding sites. Zandi pointed out, "Urbanization exacerbates the problem. In rapidly growing cities, especially in the Global South, inadequate waste management and water storage practices create ideal conditions for mosquito breeding.” The high population density in urban areas also facilitates virus transmission. Migration due to climate-related events such as floods and droughts has led to increased movement of populations into areas with new vectors, further elevating the risk of exposure to arboviruses.
Socioeconomic factors that amplify vulnerability to arboviruses are also worsened by climate change. Poverty, inadequate healthcare infrastructure, and limited access to clean water and sanitation are common in many regions affected by climate change, making it harder to control the spread of these diseases. In regions where the burden of arboviral diseases is already high, the lack of resources for vector control and outbreak response programs leads to increased morbidity and mortality.1
Zandi stressed, "Poverty, lack of infrastructure, and poor healthcare systems create conditions where people are at much higher risk of infection. These regions simply don’t have the resources to deal with the rise in cases, especially with the added burden of climate change.”
The shifting landscape of arbovirus transmission presents significant challenges to public health. Traditional surveillance systems, which focus on static disease patterns, are ill-equipped to address the dynamic changes brought on by climate change. To address this, Zandi emphasized, "Current surveillance systems often fail to track the complex interactions between environmental change, vector biology, and disease spread. What we need are dynamic, integrated surveillance systems that use climate data and real-time epidemiological data to predict where outbreaks are most likely to occur." The integration of advanced technologies, including remote sensing, GIS, and AI, can significantly improve our ability to predict outbreaks and track vector populations.
Higher temperatures shorten the incubation period for viruses within mosquitoes, increasing the speed of transmission.
Urbanization and migration to areas with poor infrastructure create conditions for mosquito breeding and disease spread.
Effective surveillance, vector control methods, and community engagement are needed to manage arboviral outbreaks.
Public health responses must be expanded to include not only enhanced vector control but also innovative solutions like genetically modified mosquitoes and antiviral therapies. Zandi explained, "Genetic modification offers a transformative solution to controlling mosquito populations. Genetically modified mosquitoes carrying self-limiting genes can reduce the number of mosquitoes over time. Another promising method involves using mosquitoes infected with Wolbachia, a bacterium that prevents them from transmitting viruses like dengue and Zika."
Education and community engagement are also essential in controlling the spread of arboviruses. Public health campaigns should promote personal protection strategies, such as using insect repellent and bed nets, and encourage community-based initiatives to eliminate mosquito breeding sites. Zandi concluded, "Engaging communities is key to success. In many places, communities are already doing a lot to fight these diseases. We need to amplify that by providing them with more tools, knowledge, and support."
In conclusion, the impact of climate change on arboviral diseases represents an urgent and evolving threat to global public health. A comprehensive approach is required to mitigate these risks, including strengthened surveillance systems, innovative vector control strategies, public health education, and increased investment in healthcare infrastructure, especially in vulnerable regions. As climate change continues to reshape environmental and socioeconomic conditions, Zandi emphasized, "We need to take action now. We can’t afford to wait for the next outbreak. The time to act is now, with the right tools, strategies, and global coordination."
