Nipah virus updates: What we know so far — 10 key points and what WHO says

A surge in the lethal Nipah virus in India has triggered high-level alerts across several Asian nations, largely due to a staggering human mortality rate ranging from 40% to 75%.

Following the deaths of at least two individuals in the Indian state of West Bengal this month, authorities in Hong Kong, Singapore, Malaysia, Vietnam, and Thailand have implemented rigorous airport screenings to prevent regional transmission, according to Reuters.

Despite these precautions, the World Health Organisation (WHO) stated on Friday that the risk of the virus migrating beyond India remains low. Consequently, the global health body has not advocated for any international trade or travel sanctions against the country. However, the WHO cautioned that further human exposure is still possible, as the pathogen persists naturally within fruit bat colonies across India and neighbouring Bangladesh.

“The WHO considers the risk of further spread of infection from these two cases is low,” the agency told Reuters in an email on Friday.

It added that India had the capacity to contain such outbreaks.

“There is no evidence yet of increased human to human transmission,” it said.

The Nipah Situation in India: 10 Critical Updates

1. According to the National Centre for Disease Control (NCDC), West Bengal has recorded only two confirmed Nipah cases from December of last year to the present.
2. In response to these cases, the Indian government and West Bengal state health officials synchronised their efforts to launch extensive public health protocols.
3. Health agencies successfully identified and tested 196 individuals who had come into contact with infected patients.
4. Official reports confirm that all identified contacts tested negative for the virus and remained symptom-free.
5. Containment was achieved through rigorous surveillance, specialised lab testing, and fieldwork conducted by local and federal health departments.
6. Authorities continue to monitor the situation closely, ensuring all necessary medical safeguards remain active.
7. While sporadic, Nipah is not new to India; the southern state of Kerala is considered a high-risk zone and has seen dozens of fatalities since 2018.
8. The WHO notes this is India's seventh documented encounter with the virus and the third for West Bengal, following previous outbreaks near the Bangladesh border in 2001 and 2007.
9. Nipah is classified as a “priority pathogen” due to its high death rate, the absence of approved vaccines or cures, and the potential for dangerous mutations.
10. The infection primarily manifests as severe fever and brain inflammation (encephalitis).

Clinical Progression and Symptoms

Nipah infections progress rapidly. Once exposed, a patient typically begins showing symptoms within four days to three weeks.

Nipah belongs to the henipavirus family and is a zoonotic disease, meaning it crosses the species barrier from animals to humans. Though it appears periodically in Asia — first identified in Malaysia in 1998 — it follows three primary transmission routes:

• Animal-to-Human: Direct contact with the bodily fluids (saliva, urine, or faeces) of infected fruit bats or other animals, such as pigs, which were the primary source in the initial 1998 outbreak.
• Contaminated Food: Consumption of products tainted by bats, such as raw date palm sap or juice, or fruit that has been partially eaten by an infected animal.
• Human-to-Human: Close physical contact with an infected individual. This is frequently observed in domestic settings or hospitals, where caregivers may be exposed to a patient's bodily secretions.