raw date palm sap is the primary source of Nipah infection, but the virus can also spread through half-eaten fruits contaminated with the saliva or urine of bats. Recent research has also shown that infected mothers can transmit the virus to infants through breast milk.
Dr Barna warned that people should avoid consuming raw date palm sap and partially eaten fruits, particularly those left behind by bats. She added that breastfeeding should be stopped if a mother is infected with the virus.
In rural areas, seasonal festivals centred on drinking raw date palm sap continue to pose a major risk. Dr Barna said such events should be officially banned to reduce transmission.
“If preventive measures are taken, the spread of Nipah virus can be controlled to a large extent,” she told the state news agency while discussing transmission and public awareness.
The prevalence of Nipah virus is high in Bangladesh and India, she said. The virus typically enters the human body through contaminated fruits or fruit products such as raw date palm sap, jujube (boroi) and guava. It can then spread from person to person through close contact.
In Bangladesh, cases are usually reported during the winter months, from December to April. People can also become infected by eating fruits partially consumed by bats.
Dr Barna said the virus can be detected through laboratory testing of urine, blood and cerebrospinal fluid using PCR, ELISA and culture methods. Because Nipah is highly lethal, testing is normally carried out in Biosafety Level-4 laboratories, although inactivated samples may be tested with caution in Level-2 facilities.
Citing the World Health Organization, she said the fatality rate ranges between 40 and 75 percent. Symptoms usually appear within four to 14 days, though in some cases the virus may remain dormant for up to 45 days.
Early symptoms include fever, headache, muscle pain, vomiting, sore throat and flu-like illness. These can rapidly progress to dizziness, loss of consciousness, abnormal behaviour, severe neurological complications and respiratory distress. While a small number of patients recover initially, some later develop serious brain infections.
Dr Barna said infected individuals may show no symptoms or may develop severe encephalitis. The virus was first identified during an outbreak among pig farmers in Malaysia and Singapore in 1998–99, when 109 of 283 infected people died.
In Bangladesh, Nipah was first detected in Meherpur in 2001 and confirmed in laboratories in 2004. Since then, cases have been reported almost every year. Between 2001 and 2025, a total of 343 cases were identified across 32 districts, with 245 deaths — a mortality rate of 71 percent.
The highest number of cases has been recorded in Faridpur, followed by Rajbari. Other high-risk districts include Meherpur, Rajshahi, Naogaon, Rangpur, Pabna and Natore.
In India, three outbreaks have been recorded so far — in Siliguri in 2001, Nadia in 2007 and Kerala in 2018 — killing 45 of 66 infected patients. In Siliguri, about 75 percent of infections occurred among healthcare workers, patients and attendants. Dr Barna said all Nipah patients identified in India in 2024 and 2025 died.
She stressed the shared responsibility of the government and the public in preventing the virus. Awareness campaigns through media, posters and leaflets are essential, she said.
People should avoid raw or unclean date palm sap, although processed molasses (gur) is safe to consume. Hospitals and health centres should be equipped for Nipah detection and treatment, and healthcare workers must receive proper training.
Dr Barna also called for regular health surveillance in high-risk areas, along with prompt isolation and contact tracing during outbreaks.
She advised avoiding contact with sick people or animals, seeking medical advice if symptoms appear, and taking special precautions — including wearing masks — when caring for infected patients. Handwashing, mask use, social distancing and self-isolation after exposure are crucial, she added.
With no vaccine currently available, Dr Barna said prevention and awareness remain the only effective protection against the Nipah virus.
