What is Nipah Virus Infection, and How is it Transmitted?
Nipah virus or NiV (Henipavirus nipahense) causes Nipah virus infection, a zoonotic disease in humans and other animals. The name “Nipah” refers to the place Sungai Nipah (‘nipah river’) in Port Dickson, Negeri Sembilan, Malaysia, the source of the human case from which the Nipah virus was first isolated. This disease has a very high mortality rate (40-75%), and Nipah outbreaks have occurred in South East Africa and Southeast Asia, including India.
During the first recognized outbreak in Malaysia and Singapore, most human infections resulted from direct contact with sick pigs or their contaminated tissues and secretions. In subsequent outbreaks in Bangladesh and India, consumption of fruits or fruit products (such as raw date palm juice, or sap used to make toddy) contaminated with urine or saliva from infected fruit bats was the most likely source of infection. Human-to-human transmission of Nipah virus has also been reported among family and care-givers of infected patients.
What are the Symptoms?
Nipah virus symptoms can emerge within 4 days up to 14 days, sometimes even a month after exposure.
Early symptoms include fever, headache, muscle pain (myalgia), cough, and sore throat. In subsequent days, breathlessness may set in. Severe neurological symptoms (encephalitis) like drowsiness, disorientation, altered consciousness, mental confusion, seizures, and slurred speech, often lead to rapid deterioration and progression to coma (within 24-48 hours), and potentially death.
How is Nipah Virus Infection Diagnosed and Confirmed?
Due to non-specific early symptoms, like fever, myalgia, and headache that mimic many other infections, high clinical suspicion based on the locality, and information of past and current outbreaks, is required, making timely diagnosis a huge challenge, especially of the initial cases of a new outbreak. Often multiple samples are required like throat/nose swabs, blood, urine, and cerebrospinal fluid (CSF) by spinal tap. The timing, quantity, and quality of sample collection, as well as transport time, can affect lab accuracy and results.
Diagnostic Tests:
- RT-PCR for active infection to detect viral RNA in early stages
- ELISA to find antibodies (IgM/IgG) in serum for late stages, post-recovery, or past exposure
- Imaging by CT/MRI scans to show encephalitis signs and support the diagnosis.
Virus Isolation by culturing the virus from clinical samples in a lab setting can confirm infection. However, Nipah virus (NiV) isolation is not a routine diagnostic method for patient care due to the extreme safety requirements and time constraints. It is primarily used for research, strain characterization, and confirmatory diagnosis under highly specialized and secure conditions.
Immunohistochemistry (uses specific antibodies to detect viral proteins in chemically/formalin fixed tissue samples, allowing pathologists to visualize where the virus is in organs like the brain, lungs, and blood vessels, revealing the virus’s distribution and its role in disease), is performed post-mortem in fatal cases.
How can Nipah Virus Infections be Treated?
Once a Nipah virus infection case is diagnosed, tracing, isolation, testing, and clinical observation of all recent contacts of that patient are of utmost importance and the key to limiting and controlling an outbreak.
There are no specific licensed treatments or vaccines for Nipah virus (NiV).
Management is mainly by supportive measures like isolation, hydration, rest, and fever/pain medicines. Severe respiratory and neurological symptoms would need hospitalization in the ICU with oxygen/ventilator support, intravenous fluids, anti-seizure medications, and reduction of intracranial pressure (by mannitol, diuretics, or hypertonic saline) when needed.
Specific treatment of Nipah virus with antivirals and monoclonal antibodies is still in the research stage. NiV being highly lethal, early detection and supportive care are vital, along with instituting preventive measures in the community during an outbreak.
How can Nipah Virus Infection Outbreaks be Prevented?
To prevent Nipah virus spread in a community, stopping animal-to-human spread is the key:
- Stay away from bats and areas where they roost.
- Avoid sick pigs and clean or disinfect pig farms.
- Do not handle bats or sick animals directly.
- Do not consume raw date palm sap (boil it thoroughly before drinking).
- Wash and peel all fruits before eating, discarding any with bat bites or those that fell to the ground.
- Cook meat and animal products thoroughly.
- Strictly enforce hygiene, especially handwashing with soap and water regularly
- Use PPE (gloves, masks, gowns) when caring for suspected or confirmed Nipah patients.
- Isolate infected individuals immediately, and practice standard infection control in healthcare settings.
- Tracing all contacts of an infected case and isolating/testing them is crucial to break transmission chains.
- Community awareness, campaigns, and public education on transmission routes and preventive measures are recommended.
- Advise travelers to high-risk areas to take precautions and seek immediate medical advice if unwell after travel.
Implement robust surveillance for early detection.
Also read:
Overview of 10 Zoonotic Diseases: Infections that spread from Animals to Humans
Water and Food Borne Diseases, and Gastrointestinal Infections