Kerala has reported a fatality from a case of infection by the Nipah virus in the northern district of Kozhikode bringing back memories of the chaos in May-June 2018 when the same district reported 18 confirmed cases of which there were 17 laboratory-confirmed deaths.
It’s the high mortality associated with the virus that triggered panic across the State and the country and when it was controlled the State’s healthcare surveillance system came in for praise though, as it turned out, it was only a test-run for the pandemic of 2020.
The deadly Nipah virus has hit Kerala, prompting the state to further heighten the alertness of its health machinery to prevent an outbreak of a different infection.
The southern state witnessed a localised outbreak of 63 cases of Zika virus in July that were mostly confined to Thiruvananthapuram, however, need not be concerned about the spread of Nipah infection as preventive measures like use of masks and PPE kits
What is Nipah virus?
- Nipah virus (NiV) is a ‘zoonotic’ virus, that is, it is transmitted to human beings from animals.
- The virus can also be transmitted through contaminated food, or directly between people.
- The pathogen that causes NiV encephalitis is an RNA virus of the family Paramyxoviridae, genus Henipavirus, and which is closely related to the Hendra virus (HeV), which was isolated in Australia in 1994.
- The animal host reservoir for both HeV and NiV is the fruit bat (genus Pteropus), which is commonly known as the ‘flying fox’.
- Infected fruit bats can spread the disease to other animals as well, such as pigs — and also dogs, cats, goats, horses and sheep.
- Human beings can get infected if they come in close contact with the infected animal, bats or other animals such as pigs or its body fluids such as saliva or urine. The initial jump of the virus from animal to human is known as a ‘spillover’ event in an outbreak.
- Once the infection has moved to humans, person-to-person spread of NiV can occur.
Nipah virus: A wider threat?
- The Nipah virus was first discovered in Malaysia in 1999 during an outbreak among pig farmers. Since then, there have been multiple outbreaks, all of them in South and Southeast Asia. In all, it is known to have killed more than 260 people.
- A 2004 Bangladesh outbreak was traced back to humans consuming date palm sap that had been contaminated by infected fruit bats.
- The last outbreak in India, which hit Kerala in 2018. Those infections were all traced back to fruit bats found dead in the water of a family’s well.
- Nipah is considered less contagious than the coronavirus, but its much higher mortality rate, a longer incubation period of up to 45 days, and its ability to infect a much wider variety of animals all make Nipah a cause of significant concern for epidemiologists trying to predict and prevent the next pandemic.
- Outbreaks fanned by exotic viruses are not foreign to India: a glance at the weekly reports compiled by the Integrated Disease Surveillance Programme shows the diversity of viral or bacterial outbreaks that flash by with barely a mention, unless they threaten India’s metropolises as outbreaks of dengue, H1N1, chikungunya or malaria sometimes do.
- The State’s public health system, earlier commended only for quality primary health care, earned appreciation for its ability to establish links between the infected and their contacts and to isolate them to prevent further spread.
How did Kerala handle the earlier Nipah virus outbreaks?
- In 2018, the state health department had no past experience of handling a disease with such a high fatality rate.
- What the state then followed was the protocol for Ebola virus disease (EVD), which had been reported mainly in sub-Saharan Africa.
- Accordingly, the state adopted the strategy of tracing the contacts of the infected persons, putting them under room isolation for 21 days.
- After tracing the contacts, their route maps were prepared to further identify the secondary contacts.
- Health Department employees visited the families of the deceased to identify the persons, including relatives who may have handled the bodies of those who died of Nipah.
- A control room was opened at the district headquarters to coordinate the activities between various departments.
- Those under isolation, many of them health workers, were given psychological support and counselling to help them tide over the mental trauma caused by the highly fatal outbreak.
- The ongoing battle against the Covid-19 pandemic, coupled with the lessons learned from the Nipah outbreak of 2018, is likely to make the task much easier at all levels for the government this time.
Lessons from the coronavirus pandemic:
- There are now established protocols — at the national level — for the three key aspects of a potential pandemic: infection control, treatment and vaccination.
- When a contagion hits, the world now understands what can and cannot be controlled within each geographic region’s context.
- It is these lessons from the coronavirus pandemic that must inform future outbreaks.
- It had become routine for Uttar Pradesh and Bihar, at intervals, to report outbreaks of ‘mystery fevers’, when they were often easily diagnosable infections that were just a competent, accessible laboratory test away.
- Thus, while there is no knowing if the latest Nipah outbreak in India will peter out like in 2019 or be worse than in 2018, India must be heartened that the potential of an outbreak evokes national concern and an anticipatory response unlike the earlier and purely reactive approach.
- A standardised treatment for Nipah continues to be elusive and a spike in cases could spell disaster given the high mortality rate.
- However, some studies suggest that vaccines developed for the coronavirus, if adequately tweaked, may prove effective against the Nipah virus too.
Broader prevention efforts include:
- Increasing surveillance of animals and people in areas where NiV is known to exist.
- Increasing research on the ecology of fruit bats to understand where they live and how they spread the virus to other animals and people.
- Evaluation of novel technologies or methods to minimize spread of the virus within bat populations.
- Improving tools to detect the virus early in communities and livestock.
- Reinforcing protocols for healthcare settings on standard infection control practices to prevent person-to-person spread.
- Raising awareness about the signs, symptoms, and risk of NiV among populations at higher risk due to:
- Geographic location
- Contact with fruit bats or items contaminated by fruit bats
- Contact with pigs or animals that could come into contact with fruit bats
- Work in a healthcare setting or as a caregiver for people infected with NiV
The WHO says in its note on the Nipah virus that, the risk of international transmission via fruits or fruit products (such as raw date palm juice) contaminated with urine or saliva from infected fruit bats can be prevented by washing them thoroughly and peeling them before consumption. Fruit with signs of bat bites should be discarded.
Another potential candidate vaccine is in early human trials. Because vaccination continues to be the best bet against the disease, the very fact that global attention and capital no longer need to be coaxed to developing vaccines for tropical infections is itself a key difference in how the world approaches outbreaks in the coronavirus era.