• Health authorities in the southern Indian state of Kerala are on high alert following the latest flare-up of the deadly Nipah virus.
• The Nipah virus is considered one of the most dangerous pathogens circulating in the wild.
• First identified 25 years ago in Malaysia, Nipah is estimated to have a case fatality rate as high as 75% and has been cited as having the potential to spark another pandemic.

Health authorities in the southern Indian state of Kerala are on high alert following the latest flare-up of the deadly Nipah virus.

It comes after a 14-year-old boy died from an infection over the weekend and as authorities race to track those who came into contact with him.

Kerala Health Minister Veena George said Tuesday that the close relatives of the teenager had tested negative for the virus, according to local media reports. She added that precautionary measures such as wearing face masks in public areas could not be lifted yet.

The state's health minister has previously said that 60 people had been identified as being in the high-risk category of having the disease. All of those identified as high-risk are being tested for the virus.

The Nipah virus, which partly inspired the fictional "MEV-1" virus in the 2011 Hollywood film "Contagion," is considered one of the most dangerous pathogens circulating in the wild.

First identified 25 years ago in Malaysia, Nipah is estimated to have a case fatality rate as high as 75% and has been cited as having the potential to spark another pandemic. There is currently no vaccine to prevent infection and no treatment to cure it.

The Nipah virus is transmitted to humans from animals such as fruit bats or pigs. The virus is known to cause a lethal brain-swelling fever in humans.

The World Health Organization says human infections can range from asymptomatic infection to acute respiratory infection.

Dr. Roderico H. Ofrin, WHO Representative to India, said Tuesday that the latest Nipah virus outbreak in Kerala appeared to have a "low risk" of further transmission.

"Active and extensive contact tracing was carried out by the Kerala government. 60 people had a close contact with the 14-year-old who died and thus were categorized as high-risk contacts. They are all being tested for the virus," Ofrin told CNBC in an emailed statement.

"Considering transmission dynamics of the Nipah virus itself and the current assessment and the caseloads, this outbreak seems to have a low risk of further transmission."

Nipah virus outbreaks

Ofrin said the reason why Nipah virus outbreaks have been detected in Kerala was "multi-factorial" but emphasized that the southern Indian state has an "excellent" system for identifying, detecting and registering all suspected cases, leading to immediate public health measures.

Prior to the latest flare-up, Kerala's state government had reported four separate Nipah virus outbreaks in the region since 2018.

In an investigation published last year, Reuters reported that extensive tree loss and rapid urbanization in Kerala over recent decades had created ideal conditions for the Nipah virus to emerge.

A separate report identified Kerala as having some of the world's leading so-called "jump zones," a term used to describe the areas that are most conducive to bat-borne viruses infecting humans.

India's National Centre for Disease Control, which leads on outbreak response, was not immediately available to provide an update when contacted by CNBC on Wednesday.