It has been confirmed that three serotypes of dengue virus circulated in Nepal during this year’s severe outbreak.

According to the Epidemiology and Disease Control Division (EDCD), serotypes 1, 2 and 3 were confirmed in 334 samples collected from across the country. Dengue virus has four distinct strains—DENV-1, DENV-2, DENV-3 and DENV-4.

These three strains were confirmed in 50 samples analysed at Tribhuvan University, 272 at the National Public Health Laboratory and 12 samples at BP Koirala Institute of Health Sciences.

Dr Gokarna Dahal, chief of the Vector Control Section at the division, said serotype 1 was confirmed in 154 samples, serotype 2 in 34 samples and serotype 3 in 81 samples.

“Six samples showed results for mixed serotypes while 59 samples came negatives for the strains. There is a possibility the results are negative if the test procedure is incorrect or the dengue kits used are sub-standard,” Dahal said.

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.

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.