Author: Ishika Obeegadoo
Reviewed by Sumali Mehta
Dengue, also known as breakbone fever, is a viral disease transmitted by the Aedes aegypti or Aedes albopictus mosquitoes, which thrives in hot and humid conditions. It’s impact on the body varies: most people with dengue do not have symptoms and recover in one to two weeks. Others develop fever and body aches, and in the most severe cases, it can cause internal bleeding and death. The disease has no specific treatment. According to the WHO, between 100 to 400 million cases are reported every year, and about half the world’s population is at risk of dengue.
Dengue cases are rising fast. In 2000, there were only about half a million official cases recorded, while in 2023, over 6 million cases were recorded. While in the past, mosquitos preferred to lay their eggs in clean water, they are increasingly reproducing in sewers, puddles, and any stagnant water. WHO had identified a high global risk level for Dengue in 2024 due to 40% of the worldwide population being at risk and the rise in Dengue-related deaths. Moreover, the consequences of climate change, the ongoing El Nino phenomenon and humanitarian crises further exacerbate this risk. It therefore comes as no surprise that in January alone, over half a million cases of Dengue and over 100 Dengue-related deaths have been reported. Since the beginning of 2024, countries across the world, including Brazil, French Guyana and several parts of Africa have reported Dengue outbreaks.
The disease burden of Dengue is primarily located in low- and middle-income (LMIC) countries. Although it affects upper-middle and high- income countries as well, it is much more common in poorer areas. Social determinants of health, including ethnicity, education and socioeconomic status all contribute to higher risk of infection and subsequent mortality from Dengue. Additionally, lack of access to care, either due to an inability to pay for private services, living in a rural area with minimal road infrastructure, or issues within the healthcare system itself can all result in Dengue mortality. This is particularly important considering that when the correct type of care is not provided in the proper time window, the risk of fatal dengue outcomes is theoretically doubled. Hence, despite Dengue being present across the world, its consequences are often a lot worse in low- and middle-income countries.
As highlighted in the aforementioned WHO report, environmental factors, including poor housing quality, lack of air conditioning and climatic factors are all part of the reason for this rise in cases. Accordingly, global warming may also contribute to further increase in the population at risk for dengue, both through increased transmission in areas where it is already common, and through an expansion of the areas in which the aedes aegypti mosquito can live and reproduce. Climate change disproportionately impacts people living in LMICs both through the direct consequences of climate-related disasters and from broader environmental changes (e.g. reduced crop yields). Beyond this, LMICs often lack the infrastructure, technology, and human and physical capital to counter climate-related risks. Hence, Dengue infections are one of the many pathways through which the impact of climate change is being disproportionately felt in LMICs.
While current interventions include sterilizing mosquitoes and developing vaccines, their success is limited. Sterilizing mosquitoes requires investment in infrastructure to be deployed, and vaccines are often difficult to access for the most vulnerable parts of the population.
Ultimately, the root cause of the increase in infections is closely tied to climate change, which is here to stay. This rising public health threat can only be addressed through broader investment in housing quality, education, better infrastructure and sanitary conditions and a commitment to the reduction of poverty. In order to build climate-resilient health systems, policymakers will have to use a holistic approach, with an emphasis on preventing infection and improving quality of life.
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Ishika is a first-year PhD student in Epidemiology at the University of Ottawa. She was born and raised in Mauritius before moving to Canada. Her research interests are psychiatric epidemiology, global health and the environment.