India: restrictions following two deaths from the Nipah virus

India has limited public gatherings and closed certain schools in the state of Kerala, in the south of the country, after the death of two people from Nipah virus, a deadly virus transmitted by bats or pigs, authorities announced on Thursday.

There is no vaccine or treatment for this virus, which has a mortality rate ranging from 40% to 75%, according to the World Health Organization (WHO).

Symptoms include high fever, vomiting, and respiratory infection. Severe cases can lead to fatal encephalitis and coma.

Three other people have tested positive and more than 700 people, including 153 healthcare workers, are under observation after having been in contact with the infected individuals, according to health authorities.

– What is Nipah virus? –

The first Nipah epidemic was recorded in 1998 after the virus spread among pig farmers in Malaysia. The virus is named after the village where it was discovered in Southeast Asia.

Outbreaks of this virus are rare, but Nipah has been listed by the World Health Organization (WHO) – along with Ebola, Zika, and Covid-19 – as one of many diseases deserving priority research due to their potential to cause a global epidemic. Nipah is usually transmitted to humans through animals or contaminated food, but it can also be transmitted directly between humans.

Fruit bats are the natural carriers of the virus and have been identified as the most likely cause of subsequent outbreaks.

Symptoms include intense fever, vomiting, and respiratory infection. Severe cases can involve seizures and brain inflammation leading to coma.

There is no vaccine for Nipah virus. Patients have a mortality rate ranging from 40% to 75%, according to WHO.

– What about previous epidemics? –

The first Nipah epidemic killed over 100 people in Malaysia and led to culling one million pigs in an attempt to contain the virus.

It also spread to Singapore, with 11 cases and one death among abattoir workers who came into contact with imported pigs from Malaysia.

Since then, the disease has mainly been reported in Bangladesh and India, with both countries experiencing their first epidemics in 2001. Bangladesh has been the hardest hit in recent years, with over 100 deaths from Nipah since 2001.

Two epidemics in India have killed more than 50 people before being brought under control.

This latest Nipah epidemic marks the fourth wave in Kerala in five years. The virus killed 17 people during an initial appearance in 2018.

– Increasing animal-to-human transmissions? –

Zoonoses – diseases transmissible from animals to humans – have existed for thousands of years but have multiplied over the past 20-30 years.

The development of international travel has allowed them to spread more rapidly. By occupying increasingly large areas of the planet, humans also contribute to disrupting ecosystems and increasing the likelihood of random viral mutations transmissible to humans, experts say.

Industrial agriculture increases the risk of pathogen transmission between animals, while deforestation increases contacts between wildlife, domestic animals, and humans.

By mixing more frequently, species will transmit their viruses more often, facilitating the emergence of new diseases potentially transmissible to humans. Climate change will push many animals to flee their habitats towards more habitable lands, warned a study published in the scientific journal Nature in 2022.

According to estimates published in the journal Science in 2018, there are believed to be 1.7 million unknown viruses among mammals and birds, of which 540,000 to 850,000 could have the ability to infect humans.