DENV-3 dominates dengue infections this year as experts fear more severe complications

The DENV-3 serotype has become the dominant strain driving dengue infections in Bangladesh this year, raising concerns among health experts that the shift could lead to more severe illness, particularly in people previously infected with a different dengue variant.

Doctors are also reporting a rise in cases of expanded dengue syndrome, alongside dengue shock syndrome and prolonged fever, highlighting the need for early diagnosis, close monitoring and stronger mosquito control.

According to the Institute of Epidemiology, Disease Control and Research (IEDCR), 91.5% of dengue samples serotyped this year were identified as DENV-3, while the remaining 8.5% were DENV-2. No other serotypes have been detected so far in 2026.

The institute has conducted RT-PCR serotyping on 71 samples recently.

IEDCR Director Dr Quazi Ahmed Zaki told The Business Standard that although the number of samples remains limited, DENV-3 has clearly become the predominant serotype, replacing DENV-2, which had dominated in recent years.

He explained that severe complications, including dengue shock syndrome, are more common in secondary infections.

"If someone who was previously infected with one dengue serotype later contracts another, the body's immune response can increase the risk of severe disease," he said, noting that children, older adults and immunocompromised people remain most vulnerable.

Zaki stressed that mosquito control remains the most effective way to reduce infections and deaths, warning that rising infections are likely to result in more fatalities unless breeding sites are eliminated.

Public health expert Dr M Mushtuq Husain said the return of DENV-3 could leave many Bangladeshis more susceptible because immunity developed against DENV-2 offers little protection against a different serotype.

"For several years, DENV-2 circulated widely. If DENV-3 now becomes dominant, people previously infected with DENV-2 may become infected again and face a higher risk of severe complications," he said.

Meanwhile, the Directorate General of Health Services reported three dengue deaths and 534 new hospital admissions in the 24 hours leading up to 8am yesterday. This year's death toll has reached 50, while confirmed cases have risen to 14,690.

Doctors report more cases of expanded dengue syndrome

Dr Shahnoor Sarmin, associate professor of medicine and in-charge of the dengue ward at Dhaka Medical College Hospital, said physicians are seeing more cases of expanded dengue syndrome this year.

"Besides fever, some patients are developing myocarditis, which is inflammation of the heart muscle, and encephalitis, or inflammation of the brain. We are also seeing prolonged fever and dengue shock syndrome," she said.

Sarmin noted that it remains unclear whether the increase in such complications is directly linked to the dominance of DENV-3 because routine treatment does not include serotyping every patient. 

She added that the standard treatment protocol remains unchanged regardless of serotype.

The expert urged people to get tested as soon as fever develops, saying early diagnosis enables timely treatment and monitoring.

According to Sarmin, dengue management rests on three pillars: adequate rest, electrolyte-rich fluids and regular clinical monitoring. Patients should drink oral rehydration saline or other electrolyte-containing fluids rather than plain water, while paracetamol and sponging can help reduce fever.

She warned that the most dangerous period is often the 24-48 hours after fever subsides, known as the critical or leakage phase. Symptoms such as low blood pressure, severe abdominal pain, chest pain, cold extremities or fainting require immediate hospital care.

Sarmin also cautioned against focusing solely on platelet counts, saying that changes in blood pressure and haematocrit are more reliable indicators of life-threatening complications.