In a bid to contain outbreaks and deaths caused every year by the Japanese encephalitis (JE) virus, the Ministry of Health and Population will begin vaccinating the unvaccinated population of Nawalparasi East starting Friday.

Officials said that due to budget constraints, this vaccination drive will cover only people aged 35 years and above in the district.

“We have tried a lot to secure vaccine doses and a budget to immunise all susceptible populations,” said Dr Abhiyan Gautam, chief of the Immunisation Section at the Family Welfare Division under the Department of Health Services. “We had also made requests to aid agencies, but could not convince them. So we have managed funds from internal sources to vaccinate people in just one district.”

JE is a viral brain infection, endemic to Asia and parts of the Western Pacific. According to the World Health Organisation, it is a mosquito-borne flavivirus belonging to the same family as dengue, Zika, yellow fever, and West Nile viruses. The virus kills a third of those who fall ill and leaves up to half of those who survive with severe life-long disabilities, according to the UN health body.

As many as 35 people have died and over 175 others were infected with the JE virus that has spread to 117 local units in 45 districts of Nepal since June last year.

Health officials serving in Nawalparasi East said that 15 people were infected with the deadly virus in the district this year, and six of them died from the severity of the infection.

“The death rate from JE infection is extremely high in our district,” said Prabin Kumar Khanal, a public health officer at the Health Office in Nawalparasi East. “We will administer the vaccine dose to over 150,000 people above 34 years of age, who have not received the vaccine against the killer disease.”

Officials say both severity and death rates are very high among the unvaccinated population. Health authorities have been administering the JE vaccine through the routine immunisation programme for the last two decades. All children under 15 years of age had already been vaccinated before the vaccine was included on the routine immunisation list.

“All necessary preparations for vaccination will be completed by tomorrow [Thursday],” said Khanal. “Vaccines will be administered from health facilities or centers designated by the Health Office.”

Last year, 23 people, including one in Kathmandu Valley, died of JE in Nepal, and over 80 were infected.

Data shows that the majority—76 percent—of JE-related deaths occurred among people above 40 years of age. The deadly virus first appeared in eastern Nepal in June and gradually spread to the western parts of the country. Of the 45 affected districts, 23 are hill districts.

Lumbini province reported 11 JE deaths and 55 infections, both the highest in the country, followed by Gandaki province with six deaths and 34 infections, and Bagmati province with eight deaths and 24 infections.

Similarly, Koshi province reported four deaths and 23 infections, Madhesh province three deaths and 17 infections, Sudurpaschim province two deaths and 15 infections, and Karnali province one death and seven infections.

The number of reported cases could be just the tip of the iceberg, as tests are usually carried out only on hospitalised patients with severe conditions, officials say.

Doctors say complications from JE infection can cause permanent injuries to the brain and the nervous system. As there is no specific cure, treatment focuses on managing symptoms. However, safe and effective vaccines have been developed to prevent infection.

Health officials said that their attempts to persuade development partners, including the World Health Organisation, to support a mass JE vaccination campaign have not succeeded.

In 2005, JE killed nearly 2,000 people in Nepal—mostly children in districts in the southern plains. Nepal started administering the vaccine in 2006, eight years before the World Health Organisation officially issued prequalification certification, due to high rates of infection and deaths from the virus at the time.

In the first phase, all populations of the highly affected four districts—Banke, Bardiya, Dang, and Kailali—were vaccinated. Later, the programme was expanded to 19 other affected districts, targeting children under 15.

The government integrated the JE vaccine into routine immunisation in 2015. Even then, people continue to die, and dozens get infected every year.

The JE virus is transmitted to humans through the bite of infected Culex mosquitoes. Pigs and ducks are considered natural reservoirs of the virus.

An estimated 12.5 million people are thought to be at high risk of JE infection in Nepal.