Dengue Fever Cases Rise In Vietnam With Multiple Virus Serotypes

A surge in Dengue fever infections has led to a 26 percent increase in cases compared to the previous year. The presence of multiple virus strains is complicating prevention efforts across various regions.

Rising Infection Rates And Regional Impact

More than 170,600 people contracted Dengue fever during the first ten months of 2026, resulting in 21 fatalities. This represents a 26 percent rise compared to the same timeframe in 2025. The Southern region was the most affected, accounting for 66.8 percent of the total cases. Other impacted areas included the Central Highlands at 17.5 percent, the Central region at 9.8 percent, and the Northern region at 5.9 percent.

The Role Of Multiple Virus Serotypes

All four serotypes of the Dengue virus—DENV-1, DENV-2, DENV-3, and DENV-4—are currently active. Serotypes 1 and 2 are the most common, making up about 90 percent of all infections. Notably, serotype 3 returned in late 2024 after a long absence. Because these strains do not provide cross-immunity, individuals can be infected up to four separate times. In the Southern region during September 2026, DENV-2 was found in 69 percent of samples, while DENV-1 appeared in 27.5 percent.

Factors Driving Epidemic Growth

The epidemic is becoming harder to predict as it no longer adheres to previous seasonal patterns. Over 90 percent of infected individuals show no clinical symptoms, yet they can still spread the virus to others. Several environmental and structural factors contribute to this trend, including rapid urbanization and the effects of climate change. Additionally, mosquitoes have developed a resistance to chemical controls, further hindering containment efforts.

Prevention And Critical Care

Managing the disease is challenging because there is no specific medical treatment available. The illness typically moves from a fever stage to a critical phase, often between the third and seventh days. It is vital for patients to remain vigilant even as fever drops, as complications can emerge during this period. Effective prevention requires a combination of vaccination, eliminating standing water to stop mosquito breeding, and improving public awareness.