Why Kerala has recurrent Nipah Virus Outbreaks? Know All about Nipah Virus Encephalitis - Dr Rahul Chawla

Many of us may have seen the famous Malayalam Movie Virus during the Covid-19 lockdown (2020-2021). The movie was about the 2018 outbreak of Nipah Encephalitis and how a team of doctors, epidemiologists and health ministry of Kerala are able to contain the spread of the fatal disease. Nipah virus encephalitis, unfortunately, is back in Kerala and has already caused a mortality of a 14-year-old teenage boy as of 21.07.24.

What is Nipah Virus and How does it spread?

Nipah Virus Encephalitis is a severe and often fatal zoonotic infection caused by the Nipah virus (NiV), an RNA virus belonging to the family Paramyxoviridae. The primary natural reservoir for Nipah Virus is fruit bats, commonly known as flying foxes. It causes illness in Pigs, from where it may get transmitted to humans. Human to human transmission and transmission via droplets is also seen during the outbreaks.

It was first identified in 1998 during an outbreak in a Malaysian village, from where it derives its name. Since then, the virus has since caused several outbreaks in South and Southeast Asia. In India, Kerala has experienced recurrent outbreaks of Nipah Virus Encephalitis in last one decade.

Reasons for Recurrent Attacks of Nipah Virus in Kerala

Abundance of fruit trees vegetation that attracts fruit bats, the natural reservoir for NiV and the proximity of human settlements to bat habitats increases the risk of zoonotic transmission.

Consuming raw date palm sap, which may be contaminated by bat saliva or urine,

Human encroachment into forests, causing habitat destruction, may facilitate virus spread from bats to humans.

The warm and humid climate of Kerala provides an ideal environment for the survival and propagation of NiV in bat populations.

Symptoms

Human NiV infection may result in a variety of manifestations, including encephalitis and acute respiratory syndrome, in addition to asymptomatic infection.  

Initial symptoms associated with infection include fever, headaches, myalgia (pain in the muscles), vomiting, and sore throat. Dizziness, sleepiness, altered consciousness, and neurological symptoms indicative of acute encephalitis could follow. Atypical pneumonia and serious respiratory issues, such as acute respiratory distress, may also occur. In severe cases, patients may have encephalitis, seizures and coma developing within 24 to 48 hours.  

The incubation period, or the time between infection and the onset of symptom, ranges from 4 to 14 days.

It is estimated that between 40% and 75% of cases may result in death. Among the survivors of acute encephalitis, some may have long-term neurological issues, including personality changes and seizure disorder.

Diagnosis and Treatment

Nipah Virus can be detected in bodily fluids such as blood, cerebrospinal fluid, throat swabs, and urine through RP PCR. ELISA test can also help detect NiV-specific IgM and IgG antibodies in the blood.

CSF is an important part of the work up and also helps rule out other possible causes of Encephalitis. Routine blood investigations may show thrombocytopenia, leucopenia and transaminitis.

MRI Brain does not have any characteristic signature finding, but may have discrete high-signal-intensity lesions in the subcortical and deep white matter of the cerebral hemispheres.

Nipah virus encephalitis does not have any specific antiviral treatment, and management primarily involves supportive or Intensive Care:

Patients with severe respiratory distress or encephalitis may require mechanical ventilation.

Anticonvulsant therapy may be required to control or prevent seizures in patients with encephalitis.

Prevention

As of now, Nipah Virus does not have any vaccine available. The most important aspect of prevention is to reduce animal to human and human to human transmission.

Reducing the risk of transmission.

Avoiding Exposure to Bats and refrain from consuming raw date palm sap.

Regular handwashing and maintaining personal hygiene.

Strict infection control measures in healthcare settings, including Personal.