The Epidemiology and Disease Control Division said it has started a study on the cause of the high mortality rate caused by the infection of the dengue virus.

Since January, at least 62 people have died and around 54,000 others were infected with the virus, which spread to all 77 districts of the country, according to the Ministry of Health and Population.

“Deaths from dengue infection are too many and we have started a comprehensive study to determine the cause,” said Dr Gokarna Dahal, chief of the Vector Control Section at the division. “A team of experts will analyse the cause of deaths from various aspects.”

Dengue is a mosquito-borne disease transmitted by female Aedes aegypti and Aedes albopictus mosquitoes. The same vector also transmits chikungunya, yellow fever, and Zika, according to the World Health Organisation.

Post-monsoon season is considered fertile for dengue transmission, but Nepal has witnessed outbreaks of the deadly disease since the start of the year and in the pre-monsoon and monsoon seasons as well. Officials said that the virus has become endemic, as cases of infection have been reported throughout the year.

Experts say the reported dengue cases could be just the tip of the iceberg, as around 90 percent of the infected people do not show any symptoms. Those closely tracking the cases suspect many more people may have succumbed to the disease as not all deaths get reported, just like during the Covid-19 pandemic.

Negligence in the case of management, taking preventive measures, lack of public awareness of the risks, and delay in seeking health care services after infection could be among the reasons for the high death rate due to the virus, according to experts.

An expert team has been tasked with analysing the population severely affected by the infection.

“We will also review if the preventive measures taken by the three tiers of government—federal, provincial and local—have been effective,” said Dahal.

Doctors say many people infected with dengue have not been seeking hospital care, which is also the reason for the decline in reported cases.

Dengue virus serotype 1 (DENV-1), 2 (DENV-2), and 3 (DENV-3) have been found responsible for the dengue epidemic in the country. Studies were carried out at the Tribhuvan University and the BP Koirala Institute of Health Sciences, according to officials at the Health Ministry. Another extensive study jointly carried out by the National Public Health Laboratory and the Nepal Health Research Council has also been completed.

Dengue cases have declined significantly amid dipping temperatures. But 15 to 20 people are still testing positive for dengue every day.

Entomologists warn that dengue spread has gone down naturally, but the risks remain. They say that a new surge could start once the temperature rises, as no serious initiatives have been taken to destroy the eggs of infected mosquitoes.

“All deaths from dengue virus should be analysed thoroughly and its underlying cause established,” said Sishir Panta, an entomologist. “Many other shortcomings could be responsible for the spread of the virus and its high severity and death rate, which should also be analysed properly and further plannings done.”

Nepal has witnessed a dengue epidemic every two or three years.

In 2019, at least six people had died and more than 17,000 had been infected by the deadly virus in 68 of the 77 districts.