Public health officials are closely monitoring a small outbreak of Nipah virus in West Bengal, India, after two healthcare workers at a private hospital in Barasat (North 24 Parganas district) tested positive for the virus. The World Health Organization (WHO) was notified of the cases on , and laboratory confirmation was received from the National Institute of Virology in Pune on .
While concerning, health authorities currently assess the risk of the virus spreading beyond India as low. This assessment is based on the prompt response from Indian health officials, including extensive contact tracing and surveillance, as well as the nature of the outbreak thus far.
What is Nipah Virus?
Nipah virus is a zoonotic disease, meaning it originates in animals and then spreads to humans. The primary reservoir for the virus is fruit bats. Human infections typically occur through exposure to infected animals or consumption of food contaminated with their bodily fluids – saliva, urine, and excreta. Human-to-human transmission is possible, but considered rare and requires close contact with an infected individual during the acute phase of illness.
The incubation period for Nipah virus ranges from 3 to 14 days, although cases have been documented with incubation periods extending up to 45 days. Diagnosis is confirmed through RT-PCR testing of bodily fluids and antibody detection using ELISA during both the acute and recovery phases of the illness.
The spectrum of Nipah virus infection in humans is wide, ranging from asymptomatic infection to severe, life-threatening conditions. Symptoms initially resemble the flu, including fever, headache, muscle aches, vomiting, and sore throat. As the illness progresses, neurological symptoms such as dizziness, drowsiness, and altered consciousness can develop, indicating acute encephalitis. Some patients experience respiratory complications, including atypical pneumonia and acute respiratory distress. In severe cases, encephalitis and seizures can lead to coma within 24 to 48 hours.
Current Situation in India
Both confirmed cases in West Bengal involve 25-year-old healthcare workers. Both individuals developed symptoms in late December 2025 and were admitted to the hospital in early January 2026. As of , the male patient showed signs of clinical improvement, while the female patient remains on mechanical ventilation.
Indian health authorities have been proactive in containing the outbreak. Over 190 contacts linked to the two cases have been identified, tested, and monitored. Importantly, all close contacts tested negative for the virus, suggesting no ongoing human-to-human transmission as of .
This outbreak represents the third documented instance of Nipah virus infection in West Bengal, with previous outbreaks reported in Siliguri in 2001 and Nadia in 2007. Enhanced surveillance and infection prevention and control measures are currently in place while investigations continue to determine the source of exposure.
Global Risk Assessment
The WHO currently assesses the risk posed by Nipah virus as moderate at the sub-national level (within West Bengal) and low at the national, regional, and global levels. The Global Virus Network (GVN) echoes this assessment, stating that while the cases are serious, they are not unexpected given the sporadic nature of Nipah virus outbreaks in South Asia, particularly in India and Bangladesh.
According to Linfa Wang, PhD, director of the GVN Center of Excellence at Duke-NUS Medical School in Singapore, “the risk of regional or global spread of Nipah virus is very low.” He further explained that these outbreaks are often driven by specific cultural and environmental factors rather than sustained human transmission.
Treatment and Prevention
Currently, there are no licensed vaccines or antiviral medications specifically approved for the treatment of Nipah virus infection. However, early supportive care can significantly improve a patient’s chances of survival.
Researchers are actively working on developing both vaccines and antiviral therapies, with several candidates showing promise in animal trials. Dr. Wang emphasized the need for sustained public funding and international collaboration to accelerate the development and availability of these crucial medical countermeasures.
Public health officials recommend strengthening community awareness regarding risk factors, such as the consumption of date palm sap, and implementing measures to reduce both animal-to-human and human-to-human transmission. The WHO does not recommend any travel or trade restrictions at this time.
