The spread of the dengue virus has continued unabated across the country despite dipping temperatures.

According to the Epidemiology and the Disease Control division, an agency responsible for outbreaks of diseases in the country, 291 people from various districts including Kathmandu were infected in December. In Kathmandu, as many as 27 cases of dengue infections have been recorded so far this month, according to Dr Gokarna Dahal, chief of the Vector Control Section at the division.

“The spread of dengue infection has slowed due to a decline in temperature but it has not stopped,” Dahal said. “The majority of the infections are being reported from Tanahun, Jhapa, and Kaski, among other districts.”

Dengue is a viral disease transmitted by the female Aedes aegypti and Aedes albopictus mosquitoes. According to the World Health Organisation, the same vector also transmits chikungunya, yellow fever, and Zika virus.

Last year, 88 persons died and more than 54,000 were infected by the virus, which had spread to all 77 districts. At the time, hospitals in Kathmandu Valley were overwhelmed with dengue patients and pharmacies had run out of paracetamol, the most widely used medicine to treat fever.

In 2019, the disease killed at least six people and more than 16,000 were hospitalised across the country. The virus had spread to 68 districts at the time.

Public health experts suspect health authorities are understating the number of dengue-related deaths as, in several districts, there are reports of more casualties than what has been officially confirmed.

They say the real number of infected persons could be several times higher, as the government’s case reporting system is ineffective and more than 80 percent of cases are asymptomatic. Many people infected with dengue show mild symptoms and do not need treatment or can be treated with paracetamol at home.

Epidemiologists and virologists said dengue virus has of late emerged as a major public health problem in Nepal. They said that the previous assumptions about the dengue virus have become irrelevant, as its spread has continued in the winter and also in the mountainous districts.

“Most of the mountainous districts, which were considered less risky to the dengue spread, have reported the outbreaks of the virus,” said Dr Sher Bahadur Pun, chief of the Clinical Research Unit at the Sukraraj Tropical and Infectious Disease Hospital. “It was considered that the outbreak would happen mostly in the post-monsoon season but hospitals have been seeing an uninterrupted flow of dengue patients, which indicates that the deadly disease became endemic in our country long ago.”

What concerns experts the most is that authorities scrambled to contain the spread only after the major outbreak of the virus. They say it will not be possible to contain the spread of infection after temperature rises and rainfall starts.

Officials at the Ministry of Health and Population concede that only long-term measures can control the spread.

“We have prepared a comprehensive action plan to control the dengue spread,” said Dahal. “We are planning to hold orientation programmes to sensitise local bodies on preventive measures to cut the risk of outbreaks.”

Dengue-transmitting mosquitoes breed in clean water and bite people in daylight. Uncovered water tanks and other discarded objects such as plastic cups and bottles could be breeding grounds for the dengue-carrying mosquitoes.

Symptoms of dengue include mild to high fever, severe muscle pain, rashes, severe headache and pain in the eyes, doctors say. Patients with these symptoms are advised to seek immediate treatment. While there is no specific cure for the disease, early detection and access to proper medical care can prevent death.

A report by the United Nations titled ‘Climate Change 2022: Impacts, Adaptation and Vulnerability’ states that at least six major vector-borne diseases have recently emerged in Nepal and are now considered endemic, with climate change implicated as the primary driver.

The report also showed increasing evidence that climate change has extended the elevational distribution of Anopheles, Culex and Aedes mosquitoes, which carry viruses to above 2,000 metres in Nepal.