28/01/2026
Nipah virus (NiV) is a serious virus that is transmitted from animals to humans and can also spread from person to person. It causes acute respiratory infection and fatal encephalitis, with a mortality rate of approximately 40–75%.
1. Virus Source and Transmission
- Natural Host: Fruit bats (Pteropodidae). The virus can persist in bats for a long time without causing illness.
- Main Transmission Routes:
- Close contact with the secretions, excrement, or tissues of infected animals (especially pigs and bats).
- Ingestion of food contaminated with bat secretions, such as fruit that has been bitten or fallen on the ground, or uncooked date palm sap.
- Close contact with the blood, respiratory secretions, or other bodily fluids of infected individuals can lead to human-to-human transmission (including among family members and healthcare workers).
Currently, it mainly occurs sporadically or in clusters in parts of South Asia and Southeast Asia, such as Bangladesh and some states in India.
2. Incubation Period and Symptoms
- Incubation Period: Usually about 4–14 days, but can be as long as about 45 days in some cases. - Symptom range: From asymptomatic to severe illness and even death.
The common course of illness is roughly "influenza-like symptoms first, then encephalitis/respiratory failure":
- Initial symptoms (influenza-like symptoms):
- Fever, headache, muscle pain
- Sore throat, fatigue, nausea/vomiting
- Cough, shortness of breath, flu-like symptoms
- Progression and severe manifestations:
- Dizziness, drowsiness, altered consciousness, confusion
- Seizures, epileptic seizures, acute encephalitis, which can rapidly worsen to coma within 24–48 hours
- Atypical pneumonia, acute respiratory distress, severe respiratory failure, possibly requiring intubation and mechanical ventilation
- Death and sequelae:
- Case fatality rate is approximately 40–75%, varying depending on the outbreak.
- Approximately 20% of survivors may experience long-term neurological sequelae, such as memory problems, cognitive impairment, persistent seizures, or tremors. - There are also reports of "delayed/recurrent encephalitis," where neurological symptoms reappear months or longer after recovery.
3. Diagnosis
- Primarily relies on laboratory testing:
- RT-PCR testing of upper respiratory tract swabs, blood, or cerebrospinal fluid.
- Serum antibody testing (IgM, IgG) to confirm recent or past infection.
- When neurological symptoms are present, doctors may order brain imaging (MRI) and other examinations to assess the encephalitis status.
- Because initial symptoms are very similar to those of the common flu or pneumonia, a history of exposure (contact with animals/travel to high-risk areas) combined with neurological symptoms are important clues.
4. Current Treatment Status
- Currently, there is no definitive treatment or widely available vaccine for Nipah.
- Standard practice is hospitalization for aggressive supportive care:
- Close monitoring of vital signs and neurological status.
- Oxygen or ventilator support; management of acute respiratory distress/pneumonia.
- Control of fever, pain, seizures, and intracranial pressure; maintenance of fluid and electrolyte balance.
- Strict isolation measures to reduce hospital-acquired and community transmission.
- Drugs under investigation or with limited use:
Ribavirin: Used in small quantities during the early outbreak in Malaysia, but clinical evidence is limited and its effectiveness is uncertain.
Monoclonal antibodies such as m102.4: Phase I clinical trials have been completed, and some have been administered under compassionate use in post-exposure or severe cases, but it remains in the research stage.
Remdesivir: Animal studies show that it can reduce mortality as post-exposure prophylaxis or early treatment, but sufficient human data is still lacking.
