Dr. Shyam P Lohani

Recent news about Nipah virus outbreaks in neighbouring India has caused concern over its spread in Nepal. The Ministry of Health and Population (MoHP) accordingly has urged the public to remain alert for possible spread of infection.
Nipah virus (NiV) is a zoonotic disease as it spreads to humans through animals. The virus is highly lethal. According to World Health Organisation (WHO), the fatality rate is up to 75 per cent. The severity of outbreaks depends on how well cases are managed in the area. However, the Nipah virus is much less contagious than coronavirus with the reproductive number estimated to be around 0.5.

Emergence
The first known outbreak occurred in Malaysia and Singapore in 1999 from pig farmers. However, no subsequent new outbreaks have been reported in Malaysia since then. Nearly 300 people were infected, and more than 100 infected died from the first outbreak. Now, outbreaks are common in other parts of Asia such as India and Bangladesh.

In 2001, Bangladesh recorded its first outbreak and nearly annual outbreaks have occurred there since then. Periodic outbreaks have been reported from eastern India. The WHO has cautioned that other countries, including Indonesia, Cambodia, Madagascar, Thailand, the Philippines, and Ghana, may be at risk as evidence has been found in the known natural reservoir and several other bat species.

The animal host for the virus is infected fruit bats also known as flying foxes. These bats can spread it to other animals, such as pigs, goats, sheep, horses, cats, and dogs. Those animals along with the bats themselves can infect people. The possibility of human to human transmission has been noted. The animal to human transmission occurs with the direct contact with infected animals or the fluids from their bodies like blood, pee, or saliva. Food contaminated with body fluids of infected animals and close contact with an infected person or their body fluids like nasal or respiratory droplets, pee, or blood can also transmit the infection, particularly among healthcare professionals caring for sick people.

Some people with the Nipah virus may remain asymptomatic but still transmit the infection to others as the reservoir. In some people, the virus can cause dormant or latent infections meaning symptoms or death could happen months or even years after contact with the virus. The common symptoms of the Nipah virus usually start within four to 14 days of exposure. Its symptoms include fever, headache, cough, sore throat, trouble breathing, and vomiting. Those symptoms may be followed by seizures and encephalitis, or brain swelling. Disorientation, drowsiness, and confusion are common symptoms of brain swelling. The infected symptomatic people may go into a coma within 24 to 48 hours. People surviving from encephalitis make a full recovery. Convulsions or personality changes have been reported in some people as long-term consequences.

There are no drugs or vaccines available yet to treat a Nipah virus infection. The symptomatic and supportive care is the mainstay of the management. The primary treatment measures are based on rest, hydration, and treating specific symptoms as they occur. The use of monoclonal antibodies and remdesivir has not proved much beneficial. The use of another antiviral drug, ribavirin, in a small number of initial Malaysian outbreaks, has not produced clear result on how well it works.

Unlike the coronavirus, awareness of the Nipah virus is extremely low among the general public, hence making it difficult to prevent, diagnose and treat. As there is no vaccine against Nipah virus, the key to lower infection rates in people is through awareness. This includes avoiding contact with infected people and washing hands regularly, especially after visiting to the infected people. The virus is not always suspected in patients showing symptoms and often missed the diagnosis of Nipah infection. PCR tests using samples of bodily fluids are mainly used to confirm infection of the virus, along with antibody detection methods.

Prevention
The best way to prevent an outbreak is to act swiftly at the beginning of infection. It is wise to carry out routine and thorough cleaning and disinfection of pig farms. At the first sign of an outbreak, areas with animals should be placed in quarantine immediately. Healthcare staff responsible for caring for patients with suspected or confirmed infection, or handling specimens from them, should strictly implement standard infection control protocol. It is recommended to avoid close and unprotected physical contact with Nipah virus-infected people. People visiting and/or caring for infected people should regularly wash their hands with soap and water.

As human-to-human transmission has been reported, particular healthcare settings, contact and droplet precautions should be used in addition to standard infection control measures. Airborne precautions while treating infected animals and humans may be required in an outbreak situation. While dealing with samples taken from suspected cases, only trained staff should be allowed to handle specimens in suitably equipped laboratories.
The best approaches to preventing Nipah virus infection are to properly clean fruits before consuming, eating well-cooked vegetables, keeping cowsheds and farms clean. Similarly, the use of gloves and masks during animal slaughtering and cooking meat, drinking boiled water, washing hands with soap and water frequently is recommended as preventive measures against the virus.

(Prof. Lohani is the founder and academic director at Nobel College. lohanis@gmail.com)