The majority of dengue infections in Dhaka this year are of the dengue virus serotype 3 (DENV-3), the strand that triggered the 2019 dengue outbreak, researchers said on Sunday.
Researchers at the Bangladesh Science and Industry Research Council (BCSIR) came to this conclusion after genome sequencing 20 samples of the virus from a hospital in the capital.
"We have sequenced 20 samples and all of them were DENV-3. This serotype-3 is infecting most people in Dhaka. Patients' platelets are rapidly declining after contracting the virus," said BCSIR chief scientific officer, Professor Selim Khan, presenting the study report.
He added that a recent study suggests that dengue can spread through breast milk and blood transfusions.
Saif Ullah Munshi, head of the Virology Department at Bangabandhu Sheikh Mujib Medical University (BSMMU), said, "Last year, most dengue infections in the country were caused by DENV-1 and DENV-2 serotypes. But this year, most of the infections appear to be caused by DENV-3. This strand was first identified in the country in 2017."
"Former DENV-1 and DENV- 2 patients are suffering from critical conditions when re-infected with DENV-3, and that's why there are more deaths this year," he said.
"People previously infected with DENV-1 and 2 are more likely to show symptoms such as bleeding, blood clots, abdominal pain, and bloating, when they are re-infected with DENV-3."
"Patients usually don't experience any other symptoms except fever when they first contract dengue. But a second infection will increase the risk of death from the virus," he warned.
Of the four types of dengue virus, DENV-1 and 4 are likely to cause more harm than DENV-2 and 3, Munshi added.
BCSIR Chairman Professor Aftab Ali said it was not possible to identify the effects of dengue virus infections from these mutations, due to lack of research on the subject.
Noting that samples were collected from only one hospital in the capital, he said more genome sequencing is needed to determine the spread of dengue across the country.
He said more genome sequencing will help in finding a cure for the virus.
Dengue cases have been steadily rising since July alongside the deadly wave of the Covid-19 pandemic. So far, 41 people have died across the country from the mosquito-borne virus. The number of hospitalisations has surpassed 9000.
According to data released by the Directorate General of Health Services, over 1 lakh people were hospitalised after contracting the mosquito-borne viral infection in 2019. IEDCR confirmed at least 148 deaths from the virus that year.
Last year, the virus claimed 93 lives. Previously, the same number of confirmed deaths were reported in 2000, with 5,551 infections.