Nipah Virus

Intro

Nipah virus (NiV) is a rare but extremely dangerous zoonotic virus that causes severe brain inflammation (encephalitis) and respiratory illness in humans. It is classified as a biosafety level-4 pathogen and is associated with some of the highest case-fatality rates of any known infectious disease.

There is currently no approved vaccine or curative treatment.

Key Points

Reported fatality rates commonly range from 40–75%
Natural reservoir: fruit bats (Pteropus species)
Transmission includes human-to-human spread
Rapid neurological deterioration is common
Survivors may experience long-term or delayed neurological effects

Background

Nipah virus was first identified in 1998–1999 during an outbreak among pig farmers in Malaysia. Since then, repeated outbreaks have occurred primarily in Bangladesh and eastern India, often linked to bat-to-human spillover events.

The virus belongs to the Henipavirus genus and is closely related to Hendra virus.

Transmission

Nipah virus spreads through:

Consumption of food contaminated by fruit bats (notably raw date palm sap)
Contact with infected animals (such as pigs)
Close contact with infected humans via bodily fluids, including respiratory secretions

Human-to-human transmission has been documented in multiple outbreaks, particularly in healthcare and household settings.

Symptoms

Early symptoms

Fever
Headache
Muscle pain
Vomiting
Sore throat

Severe disease

Drowsiness and confusion
Seizures
Acute encephalitis
Respiratory distress
Rapid progression to coma

Death may occur within days of neurological onset.

Diagnosis

Diagnosis relies on:

RT-PCR testing of blood, cerebrospinal fluid, urine, or respiratory samples
Serological testing in later stages
MRI imaging, which often shows characteristic encephalitic changes

Testing is typically performed in specialised reference laboratories.

Treatment

There is no proven antiviral therapy for Nipah virus infection.

Management consists of intensive supportive care, including:

Airway and respiratory support
Seizure control
Management of raised intracranial pressure
Strict infection-control measures

Prognosis

Even with modern intensive care, mortality remains high. Some survivors develop:

Persistent neurological deficits
Personality or cognitive changes
Delayed relapse encephalitis months or years after recovery

FAQ

Q: Is Nipah virus airborne? A: There is no evidence of long-range airborne transmission. Spread occurs through close contact and exposure to bodily fluids.

Q: Why is Nipah virus closely monitored? A: Because of its high lethality, ability to spread between humans, and lack of vaccines or curative treatments.