In the early 1950s, dengue had yet to become the major public health threat it is today. That changed when Manila, the Philippines, experienced an outbreak of dengue hemorrhagic fever (DHF) in 1953–1954. It was the first known recorded DHF epidemic.
Over the next two decades, the disease spread across Southeast Asia, becoming a leading cause of hospitalisation and child mortality in the region.
Manila, however, was not where the dengue virus originated. The virus had circulated in nature long before DHF was recognised as a public health concern. So how did a virus that once existed mainly in forest ecosystems become a major epidemic in Southeast Asian cities?
Before Reaching Humans, Dengue Circulated in Forests
The dengue virus has been circulating for centuries. According to researcher Duane Gubler, it originally followed a natural transmission cycle in the tropical forests of Asia and Africa. Mosquitoes of the Aedes genus living in forest canopies transmitted the virus to non-human primates, allowing it to persist within these ecosystems.
Under natural conditions, viruses from this cycle did not regularly spread into human settlements. However, research in Journal of Virology found an evolutionary link between dengue viruses that circulate among humans and those identified in non-human primates in West Africa and Malaysia.
Through genetic analysis, researchers estimated that some dengue serotypes responsible for human epidemics evolved from forest-dwelling ancestors between 100 and 1,500 years ago.
This suggests that dengue did not emerge after World War II. Rather, the war and subsequent environmental changes accelerated its spread on a much wider scale.
How World War II Changed Dengue’s Spread
World War II marked a turning point in the modern spread of dengue. The movement of troops and military supplies across Asia and the Pacific helped carry both the virus and Aedes aegypti mosquitoes into different territories. Wartime ecological disruptions also created conditions that favoured mosquito-borne disease transmission.
The challenges continued after the war ended. Economic growth during the 1950s drove large-scale migration into cities such as Manila, Bangkok, and Jakarta. Yet urban expansion was not always accompanied by adequate infrastructure.
Crowded settlements with limited access to clean water, drainage, and waste management created numerous breeding grounds for mosquitoes. Under these conditions, dengue transmission became increasingly difficult to control.
Manila was among the first cities to experience a DHF epidemic in 1953–1954. Bangkok followed in 1958, while Singapore, Malaysia, and Vietnam began reporting cases during the 1960s. Indonesia first recognised DHF cases in Jakarta and Surabaya in 1968. By the mid-1970s, DHF had become a leading cause of hospitalisation and child mortality in several Southeast Asian countries.
From Southeast Asia to the Rest of the World
Southeast Asia was among the first regions to experience widespread DHF epidemics. In fact, DHF emerged as an epidemic in the Americas around 25 years after its spread across Southeast Asia.
In the Americas, the resurgence of Aedes aegypti following the end of mosquito eradication programmes in the early 1970s paved the way for dengue transmission. DENV-1 was reported in 1977, followed by DENV-2 and DENV-4 in 1981, and DENV-3 in 1994.
Today, dengue poses a public health threat in more than 100 countries. The World Health Organization estimates that between 100 million and 400 million infections occur each year.
Meanwhile, a study by Bhatt and colleagues estimates around 390 million infections annually, of which 96 million result in symptoms. Asia accounts for approximately 70 percent of this symptomatic disease burden.
In 2024, the WHO received reports of more than 14.6 million dengue cases and over 12,000 deaths, the highest figures recorded in any 12-month period. More than 13 million cases came from the Americas. Between January and July 2025, over 4 million cases and 3,000 deaths were reported across 97 countries.
From Manila in the 1950s to epidemics spanning continents today, dengue’s history shows how warfare, urbanisation, and environmental changes can reshape the spread of disease. A virus that once circulated within natural forest cycles has become a public health challenge facing cities around the world.
References:
- Bhatt, S., Gething, P. W., Brady, O. J., Messina, J. P., Farlow, A. W., Moyes, C. L., Drake, J. M., Brownstein, J. S., Hoen, A. G., Sankoh, O., Myers, M. F., George, D. B., Jaenisch, T., Wint, G. R. W., Simmons, C. P., Scott, T. W., Farrar, J. J., & Hay, S. I. (2013). The global distribution and burden of dengue. Nature, 496, 504–507. https://doi.org/10.1038/nature12060
- Dengue haemorrhagic fever and Japanese B encephalitis in Indonesia. (1988). PubMed. https://pubmed.ncbi.nlm.nih.gov/2851186/
- Gubler, D. J. (1998). Dengue and dengue hemorrhagic fever. Clinical Microbiology Reviews, 11(3), 480–496. https://doi.org/10.1128/CMR.11.3.480
- Gubler, D. J. (2011). Dengue, urbanization and globalization: The unholy trinity of the 21st century. Tropical Medicine and Health, 39(4 Suppl), 3–11. https://pmc.ncbi.nlm.nih.gov/articles/PMC3317603/
- Perspectives and lessons from the Philippines’ decades-long battle with dengue. (2022). The Lancet Regional Health – Western Pacific. https://www.thelancet.com/journals/lanwpc/article/PIIS2666-6065(22)00120-1/fulltext
- Wang, E., Ni, H., Xu, R., Barrett, A. D. T., Watowich, S. J., Gubler, D. J., & Weaver, S. C. (2000). Evolutionary relationships of endemic/epidemic and sylvatic dengue viruses. Journal of Virology, 74(7), 3227–3234. https://doi.org/10.1128/JVI.74.7.3227-3234.2000
- World Health Organization. (2025). Dengue and severe dengue [Fact sheet]. https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue
