Aedes-borne Diseases, Crisis, and Opportunity

Dengue, described at the turn of the century as “An Environmental Plague for the New Millennium,” is living up to the name. More than half the world’s population is now at risk, as transmission—fueled by climate change, urbanization, and population mobility—has exploded, with 14 million cases recorded in 2024. Swelling ranks of Aedes albopictus mosquitoes—vectors, along with Ae. aegypti, of dengue, as well as chikungunya, Zika, and yellow fever—now threaten the U.S., Europe, and China, where they caused a crippling chikungunya outbreak in 2025.

Yet Aedes-borne diseases draw far less attention and funding than other diseases known as major childhood killers, such as malaria, respiratory and diarrheal diseases, and HIV. With malaria, for example, donated nets, diagnostics, and drugs reliably reduce illness and death—a clear return on investment. 

It’s more challenging for dengue and chikungunya. Bed nets have very limited impact (Aedes feed during the day); diagnostics, therapeutics, and vaccines are much more complex. Two vaccines completed clinical trials and received international approval, but the process of creating a vaccine that safely protects against all four virus strains without causing adverse immune reactions is complex. 

At the same time, the economic impact of dengue and chikungunya may be far greater and insidious than the headline-grabbing child mortality figures for other disease-prevention investments.

• Globally, Aedes-borne diseases cost $3.3 billion annually; total costs can surge significantly higher during peak outbreak years, causing tens of billions in financial strain.
• The 2016 Zika outbreak in Latin America and the Caribbean cost $3.5 billion. 
• At the family level, a cost-of-illness study in Bangladesh showed the overall out-of-pocket expenditure for dengue treatment was 56% of monthly household income. However, in the poorest quintile, it exceeded 139% of total household income, plunging families into debt. 

It’s going to get worse.

Global warming is estimated to have caused 18% of historical dengue. With future warming this could further increase incidence by 49%–76% by midcentury, with cooler regions projected to double in incidence; for Bolivia, population-weighted average dengue is projected to increase by 811%.  

Momentum is building to change that trajectory. The Asia Dengue Summit, held last month in Singapore, drew nearly 600 delegates from 22 countries, with 50 international speakers and 225 abstracts submitted—a seminal moment and big step toward an effective global response for this neglected tropical disease. [MH2] The first day of the summit commemorated June 15 as an annual defining moment for dengue—building on the first ASEAN Dengue Day on June 15, 2011, advocating that this become the WHO-recognized World Dengue Day. What began as an effort to consolidate regional prevention efforts has grown into a global call to action that mirrors the disease’s rapid global expansion—supported by advocacy led by the International Society for Neglected Tropical Diseases, Asia Dengue Voice & Action, and the more recently formed Collective Action on Dengue.

The summit helped to strengthen efforts related to dengue immunity and disease severity; clinical management and patient care; innovation in prevention and control; and strengthening surveillance and preparedness. This year, six regional and global organizations signed a memorandum of understanding (MoU) to formalize their collaboration. The MoU establishes a framework for ongoing public education, advocacy, and knowledge-sharing efforts, as well as the exchange of outbreak experiences and best practices. It will also support the development of joint publications, policy recommendations, educational resources, and regional awareness campaigns—reflecting a growing recognition that dengue requires coordinated action across countries, sectors, and disciplines.

Building on the momentum of the Asia Dengue Summit and proposed World Dengue Day, the dengue narrative needs to shift. It can no longer be seen just as a second-tier health issue behind malaria. Especially in this age of restricted donor health funding, development partners, ministries of finance, chambers of commerce, businesses, and families are urged to see the positive return on investment for control of dengue and other Aedes-borne diseases. Dengue is a develoment challenge that can be neglected no more.

Michael B. Macdonald, ScD, is a public health entomologist in Catonsville, Maryland.

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