Meet the Nipah virus, which scares Asia with up to 75% mortality

The death of a 12-year-old boy last week in a hospital in the city of Calicut, on the west coast of India, has drawn global media attention for the cause: according to Kerala state health authorities, the child died in resulting from an infection caused by the Nipah virus (NiP), a pathogen with a mortality rate of up to 75%, according to the WHO (World Health Organization).

Hospitalized for a week, according to the US broadcaster CBS, the young man had a very high fever and his situation was getting worse, with signs of encephalitis (inflammation and swelling in the brain) and he died.

According to the TV network, the boy had contact with 188 people before he died. All are undergoing quarantine or are hospitalized in an attempt to contain the spread of the virus.

The Nipah Virus

Much more deadly than the SARS-CoV-2 coronavirus, although less transmissible, Nipah is a zoonotic virus, meaning it is transmitted from animals to humans. It can also be transmitted through contaminated food or directly between people.

The fruit bats of the family Pteropodidae are the main vectors, although the pathogen has, in its first outbreak in Malaysia in 1999, infected pigs, horses, goats, sheep, cats and dogs.

According to the WHO, most of these first infections occurred after unprotected human contact with the secretions of sick pigs or their contaminated tissues. In the outbreaks that occurred later in Bangladesh and India, the most likely source of infection was the consumption of fruits or by-products (such as the popular date palm juice) contaminated with bat urine or saliva.

Mature extracellular particle of Nipah virus obtained by electron micrograph (Source: NIAID - Nipah Virus Particle/Wikimedia Commons/Reproduction)Mature extracellular particle of Nipah virus obtained by electron micrograph (Source: NIAID – Nipah Virus Particle/Wikimedia Commons/Reproduction)Source: NIAID – Nipah Virus Particle/Wikimedia Commons

Symptoms of Nipah Disease

Human beings contaminated by the Nipah virus can present, according to the WHO, from asymptomatic infection to respiratory infection (mild or severe) and fatal encephalitis. The main symptoms initially reported are: fever, headache, myalgia (muscle pain), vomiting and sore throat. Dizziness, drowsiness, altered consciousness and neurological signs may also occur, which may be indicative of acute encephalitis.

The incubation period, which occurs between infection and the onset of symptoms, ranges from 4 to 14 days. In severe cases, encephalitis and seizures progress to coma within 24 to 48 hours. Some of these people even manage to survive and fully recover, but about 20% of patients are left with neurological sequelae, such as seizure disorders and personality changes, and may even present relapses.

Can Nipah cause a pandemic?

Although the Nipah outbreaks have never reached a pandemic level since their discovery in 1999, it is possible, according to health authorities, that it could give rise to a pandemic. Therefore, WHO has already included the virus in its list of diseases and pathogens prioritized for research and development in emergency contexts.

According to the main formulator of international health standards, there is no type of treatment for the Nipah virus, that is, no type of vaccine to prevent contamination or drugs that improve the condition.