Explained: The resurgence of Nipah virus in Kerala

NEW DELHI: Amid the global rise in Covid cases, India is seeing a fresh scare with the resurgence of Nipah virus in Kerala’s Kozhikode district.

Nipah is a zoonotic virus (transmission of virus from animal to humans), which can be spread through contaminated food or directly between humans on exposure to secretions.

The fresh outbreak of Nipah started with the death of a person on August 30 but it was on Monday when a contact of the person, who passed away, tested positive, it was declared that Nipah is back.

According to Kerala Health Minister Veena George, there have been two deaths since August 30, and there are three active cases currently, including a 24-year-old health professional who tested positive for Nipah on Wednesday night.

The state government on Wednesday evening said at least 706 people, including 153 health workers, were undergoing tests to check the spread of the virus. The results are awaited.

The virus has surfaced again in Kerala for the fourth time. The present cases have been reported about 15 km from where the initial Nipah virus outbreak in southern India was first identified in Kozhikode in May 2018 and then again in 2021. In June 2019, a sporadic case of Nipah resurfaced from a geographically different location, at Kochi.

“The symptoms and signs of zoonotic diseases can greatly differ based on the disease and the organ systems affected. Fever, cough, respiratory distress, diarrhoea, nausea, vomiting, muscle aches, and fatigue are all common symptoms. It is worth noting, however, that some zoonotic diseases can display asymptomatically or with mild symptoms, making early detection and prevention difficult,” Dr Swati Rajagopal, Consultant - Infectious Disease & Travel Medicine, Aster CMI Hospital, Bengaluru, told IANS.

In addition to the usual symptoms “the central nervous system, that is the brain also gets involved, resulting in encephalitis -- inflammation of the brain. But before that people get seizures -- one or two sometimes many episodes and face confusion, disorientedness,” added Dr Ishwar Gilada, an infectious diseases expert.

“While the incubation period is only four to 14 days, the fatality or death rate is 40 to 75 per cent,” he noted.

The Nipah strain found in Kerala this time is the Bangladesh variant which is less infectious but has a high mortality rate. This strain spreads from human to human.

So far, the “fruit bat” has only been identified as the animal host reservoir from which the virus can spread the disease to other animals like pigs, dogs, cats, goats.

“The Nipah virus is not only fatal for humans, but for animals as well. The virus can also cause severe disease in animals such as pigs, resulting in significant economic losses for farmers,” Dr Rajagopal said.

The experts called for social distancing, masking and use of sanitisers, as the disease can only be prevented with caution.

“There is no treatment and no vaccine to prevent, containment is the best strategy,” Dr Gilada said. He informed that the only treatment which has been tried and successful in Phase one is M102.4 - a monoclonal antibody. The doctors also tried remdesivir and others, which proved to be unsuccessful.

Nipah was first recognised in 1999, since then it has made its mark in four or five countries: Malaysia, Singapore, Bangladesh, Philippines and India. It has never become an epidemic or pandemic.

“The virus has never become an epidemic and so it will not become one now. Reason being high mortality and relatively low infectivity,” he explained, advising to be careful about bodily fluids of bats and pigs, particularly where the infection is going on.

Dr Rajagopal asked people to maintain hand hygiene to avoid the spread of zoonotic pathogens. “Washing hands with soap and water on a daily basis is important especially after managing animals, visiting farms or animal markets, or cleaning pet waste”.

Further, vaccinate animals regularly, cook meat properly to destroy any potential pathogens and avert foodborne zoonotic diseases like salmonellosis. To avoid cross-contamination, use separate cutting boards and utensils for raw and cooked foods, the doctor said.

“When spending a lot of time in areas with high vector activity, utilise insect repellents, wear protective clothing, and take precautions to avoid tick bites. This reduces the risk of zoonotic diseases like Lyme disease and West Nile virus significantly,” Dr Rajagopal told IANS.

“Keep up to date on zoonotic diseases that are prevalent in your area. Recognise the symptoms of these diseases and seek medical attention as soon as possible if you suspect an infection.”