India / What's the Nipah virus infection that led to death of a 12-yr-old boy in Kerala?

New Delhi: Even as Kerala continues to reel under the pressure of mounting Covid-19 cases, another public health risk has announced itself in the state. A 12-year-old boy died of Nipah virus infection in Kozhikode district of Kerala early on Sunday morning.

The Centre immediately rushed a team to the state to provide technical support and state health minister Veena George said teams have already been formed to handle the situation. "As of now, there is no need to panic, but we need to exercise caution," she said.

This is not Kerala's first tryst with Nipah virus. In 2018, there was an outbreak of the disease in Kozhikode and Malappuram districts of the state. A total of 17 people lost their lives in the outbreak and 18 others were also infected.

So, what is the Nipah virus? How does it spread? What are its symptoms? Here's everything you need to know about it.

WHAT IS NIPAH VIRUS?

Nipah is a zoonotic virus, which means it spreads from animals to humans. The Nipah virus is transmitted from its natural host — flying foxes (fruit bats) — to animals and humans. Generally, it affects animals like pigs, dogs and horses, among others. If it spreads among humans, Nipah virus can cause serious illness which may result in death.

As per the World Health Organisation, the Nipah virus infects a range of animals and causes severe disease and death in people. This makes it a cause of concern for public health.

"In infected people, it causes a range of illnesses from asymptomatic (subclinical) infection to acute respiratory illness and fatal encephalitis," the WHO says in its guidelines on Nipah virus.

SYMPTOMS OF NIPAH VIRUS INFECTION

The following are the symptoms of Nipa virus infection,

1. Brain fever

2. Fever with persistent cough and difficulty in breathing

3. Acute respiratory infection (mild or severe)

4. Influenza-like symptoms -- fever, headache, muscle pain, vomiting, sore throat, dizziness, drowsiness

5. Neurological signs indicating encephalitis

As per the WHO, in some cases people may also experience pneumonia.

"Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours," the WHO's guidelines state.

The incubation period of Nipah virus is 5-14 days on average. But in some extreme cases, it can go up to 45 days, which means there is a lot of time for an infected person to unknowingly infect others.

HOW IS NIPAH VIRUS DIAGNOSED?

The main tests used to diagnose Nipah virus are real-time polymerase chain reaction (RT-PCR) from bodily fluids and antibody detection via enzyme-linked immunosorbent assay (ELISA). Other tests used include PCR and virus isolation by cell culture.

These tests are often not well suited for use in remote and rural settings, where most outbreaks occur and where containment capabilities are lacking.

HOW DOES NIPAH VIRUS SPREAD AMONG HUMANS?

The Nipah virus can spread among humans if they establish close contact with Nipah-infected people, bats or pigs. Hence, paramedical staff and close relatives of infected people are at risk.

"Bat secretions laden with the virus can infect people during climbing of fruit trees, eating/handling contaminated fallen fruits or consuming raw date palm sap/juice or toddy," the National Centre for Disease Control's guidelines on Nipah virus state.

Another possible source of infection can be the bodies of people who died due to Nipah virus. The National Centre for Disease Control (NCDC) advises that handling of the bodies be done strictly in accordance with the government advisory.

"During this emotional moment, traditional rituals and practices may need to be modified to prevent the exposure of family members to the disease," the NCDC said.

WHAT TO DO TO PREVENT SPREAD OF NIPAH VIRUS

In order to minimise and avoid transmission of Nipah virus, one should wash hands with soap and water regularly and especially after coming in contact with a potentially infected person or animal.

People should also avoid consuming raw date palm sap or toddy.

The bodies of those who lost their lives to Nipah virus should be handled as per the guidelines issued by health officials. Any laxity in this could worsen the situation.

Fruits should be consumed only after washing them properly. Half-eaten fruits lying on the ground must be avoided. These fruits could have been eaten by infected animals, especially the flying fox which is the main transmitter of Nipah virus.

While handling sick animals, care should be taken. Gloves and other protective clothing should be worn during slaughter and culling of infected animals and any contact with infected pigs should be avoided as far as possible.

HOW IS NIPAH VIRUS TREATED?

According to the World Health Organisation, currently there are no licensed drugs for treatment of the Nipah virus. The drug Ribavirin has shown to be effective against Nipah viruses in laboratory. However, human investigations have been inconclusive and the clinical usefulness of Ribavirin remains uncertain, as per WHO.

Without a licensed drug to treat it, the WHO recommends intensive supportive care for the treatment of severe respiratory and neurologic complications borne out of Nipah infection.

Most people who survive acute encephalitis make a full recovery. However, those who have survived the disease have reported long-term neurologic conditions.

"Approximately 20 per cent of patients are left with residual neurological consequences such as seizure disorder and personality changes. A small number of people suffer a relapse or develop delayed onset encephalitis, after showing signs of recovery," the WHO said.

IS THERE A VACCINE FOR NIPAH VIRUS?

Similarly, there is no vaccine for the illness yet. According to Gavi, The Vaccine Alliance, a Phase 1 clinical study of a Nipah virus vaccine candidate (HeV-sG-V) started in February 2020 and is expected to be completed in September 2021.

Taking cognisance of the seriousness of Nipah virus, the WHO has identified it as a "priority disease" for the WHO Research and Development Blueprint.

WHERE ELSE HAS NIPAH VIRUS SPREAD?

So far, Nipah virus outbreaks have mainly been reported in Malaysia, Singapore, Bangladesh and India (West Bengal and Kerala). But this does not mean that Nipah can't spread to other regions. All areas that are inhabited by flying foxes have the risk of being infected with Nipah.

The WHO says that flying foxes can be found from the east coast of Africa, across South and Southeast Asia to Australia.

"It can be conjectured that Nipah virus can emerge as a human pathogen anywhere in these distribution areas. Countries with serological evidence or molecular detection of the virus in these flying foxes include Bangladesh, Cambodia, China, India, Indonesia, Madagascar, Taiwan and Thailand," it says.