Dengue outbreaks becoming increasingly unpredictable

Vietnam's dengue situation is growing more complicated, with infections spreading widely and no longer following their usual seasonal cycles. In 2025, the country recorded the highest number of dengue cases in the Asia-Pacific region.

On November 6, the Ministry of Health's Department of Disease Prevention, in coordination with relevant organizations, held the Dengue Summit 2026 to assess the disease burden and discuss prevention strategies.

According to reports presented at the event, dengue is among the world's fastest-growing mosquito-borne infectious diseases, with an estimated 100 million to 400 million infections annually.

In Vietnam, dengue has remained a persistent public health challenge for more than four decades.

Since 1980, the country has recorded hundreds of thousands of cases, with deaths reported every year.

The incidence of dengue per 100,000 people is considerably higher than that of many other infectious diseases. It ranks first in incidence and second in mortality among infectious diseases in Vietnam.

Speaking at the conference, Hoang Minh Duc, Director of the Ministry of Health's Department of Disease Prevention, said the country had recorded more than 170,000 dengue infections and 21 deaths since the beginning of 2026.

Despite years of resource mobilization, extensive technical interventions and support from domestic and international experts, dengue outbreaks have not been controlled as effectively as expected.

Professor Nguyen Van Kinh, President of the Vietnam Society of Infectious Diseases, said infections had continued to rise significantly following the major outbreak in 2022.

More concerning, the current increase in dengue cases no longer follows the seasonal or cyclical patterns observed in previous years.

Kinh identified climate change and increased rainfall as major contributing factors.

Mosquito species responsible for transmitting dengue, particularly Aedes aegypti and Aedes albopictus, readily lay eggs in stagnant water, including rainwater collected in containers and other locations.

Increased rainfall therefore creates favorable breeding conditions, allowing mosquito populations to expand and raising the risk of outbreaks.

High disease burden complicates dengue prevention efforts

Although Vietnam has reported more than 170,000 dengue cases this year, the number of deaths remains relatively low, with a reported fatality rate of approximately 0.01%.

Nevertheless, experts warn that the disease's clinical progression remains complex and difficult to predict.

Compared with other infectious diseases, dengue represents a substantial public health burden in Vietnam and could continue to pose challenges for many years, Kinh said.

One major difficulty, according to the professor, is that more than 90% of infected individuals show no clinical symptoms.

As a result, people who are unaware of their infection may still contribute to transmission when mosquitoes bite them and subsequently spread the virus to others.

Kinh also stressed that completely eliminating mosquitoes and their larvae is virtually impossible, regardless of the intensity of control efforts.

"As long as the source of infection and the vectors transmitting the disease remain, dengue will continue to exist," he said.

He believes vaccines offer significant potential as an additional preventive measure to help bring outbreaks under better control.

To address the challenge, Kinh recommended that Vietnam's healthcare sector coordinate three major strategies: dengue vaccination, mosquito and larval control to reduce infections, and timely, effective treatment to minimize deaths.

He emphasized the importance of eliminating mosquito breeding sites while ensuring patients receive medical attention without delay.

"Without mosquito larvae, there is no dengue transmission. And treatment for dengue patients must never be delayed," Kinh stressed.

N. Huyen