According to the Dong Nai Centre for Disease Control, the province recorded 2,461 dengue cases in the first four months of 2026, including three deaths.
Authorities said the number of outbreaks rose more than 22% year-on-year, with 870 clusters recorded across the province.
Nationally, Vietnam reported nearly 45,000 dengue cases and five deaths between December 14, 2025 and April 18, according to health data cited in the report.
Medical experts said dengue was no longer concentrated mainly among children, with increasing infections now recorded among adults aged 22 to 44.
Doctors warned that symptoms such as high fever, headaches, muscle pain and nausea could easily be mistaken for flu, causing some patients to delay treatment.
Severe dengue can lead to complications including shock, internal bleeding and multi-organ failure.
Authorities stressed that early prevention and awareness remained the most effective measures as there is currently no specific treatment for the disease.