Almost 35 percent of the people who died from dengue are aged between 21 and 40 years, according to the health directorate data.

The Directorate General of Health Services (DGHS) reported eight deaths from the mosquito-borne disease and 2,168 hospital admissions in the 24 hours preceding 8:00am yesterday.

The outbreak this year has caused 493 deaths and 1,04,359 hospitalisations, the DGHS data shows.

The 21-40 age group constitutes around 46 percent of the total cases this year so far.

HM Nazmul Ahsan, associate professor of medicine at the Shaheed Suhrawardy Medical College and Hospital, said, "It is difficult to say why this age group has the highest number of deaths. But delayed visits to the hospital could be one of the reasons. People of this age group are relatively fit, and they tend to delay the first visit to the hospital."

Early consultation with a doctor and proper medication are essential if someone has dengue, he said, adding that patients should drink coconut water, saline, and home-made fruit juice to stay hydrated. He also advised vitamins and minerals to speed up recovery.

Hasan Mohammad Al-Amin, who studies Bangladeshi mosquitos at the QIMR Berghofer Medical Research Institute in Australia, said, "The main reason behind the higher casualties is that many of the patients have been infected for the second time."

Citing his own research done in 2014, he said 85 percent of the residents in the survey area previously had dengue.

"However, the majority of people are unaware of their past infections. This indicates the absence of proper surveillance. People are left uninformed and at increased risk of death," he said.

Entomologist Prof Kabirul Bashar of Jahangirnagar University said as people of the 21-40 age group go outdoors a lot, they are at risk of getting infected.

"People have to wear full sleeve tops, socks, shoes, and use mosquito nets while sleeping," he said.