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Illustration of the Nipah virus structure.
Nipah virus typically causes fever, headaches, muscle pain, vomiting, and a sore throat but can also lead to encephalitis and death.

Nipah Virus Outbreak in India: Should the US and Canada Be Concerned?

University of Toronto and Vanderbilt University researchers discuss the likelihood of a Nipah virus outbreak in North America

María Carla Rosales Gerpe, MSc, PhD

María Rosales Gerpe, MSc, PhD, is a freelance scientific writer with more than a decade of research experience in molecular biology and gene therapy. She's also a reporter for Metroland at the Cambridge Times, Cambridge, Ontario, Canada.

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Published:Oct 30, 2023
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From September 12–15, the Government of India reported a Nipah virus outbreak that claimed the lives of two people of the six confirmed infected in Kerala, India. The outbreak led to state-issued containment protocols involving the testing of at least 700 people and the closure of schools, some offices, and public transportation, according to Nature News.

Why should we be concerned about Nipah?

Since the first case described in 1998, Nipah cases have also been reported in other South Asian states like Singapore and Bangladesh. The current outbreak in Kerala is the southern state’s fourth, and India’s eighth since 2001.

According to a 2023 MDPI review, Nipah, an RNA Henipavirus from the Paramyxoviridae family that includes the Hendra virus first described in Australia, is a bat-born zoonotic pathogen that can infect pigs, with seroprevalence measured in other farm animals like cattle to a lower degree. Nipah virus typically causes fever, headaches, muscle pain, vomiting, and a sore throat but can also lead to encephalitis and death.

Spillover has occurred from bats to humans and from pigs to humans, as was the case for the first outbreak in Malaysia 25 years ago, wrote Vanderbilt University Medical Centre (VUMC)’s Robert Carnahan, PhD, professor of pediatric infectious diseases, and Silvia Ravera, PhD, senior staff scientist at Crowe Laboratory in an email to Today’s Clinical Lab.

“However, some strains of Nipah, like the one currently causing the outbreak in Kerala, can spread human-to-human,” noted the VUMC researchers. Another concern is population density.

Whereas prior outbreaks occurred in remote areas in India, the September cases stemmed from a larger metropolitan area, says Robert Kozak, PhD, assistant professor at the University of Toronto’s Department of Laboratory Medicine and Pathobiology, and clinical microbiologist at Sunnybrook Health Science Centre.

As such, “a number of infectious disease experts are watching and monitoring the outbreak,”  he says, adding that “this is a pathogen that destroys the livelihoods of people.” Kozak recounted that the first outbreak resulted in the culling of thousands of pigs, with detrimental impacts to Malaysia’s agricultural sector and national economy.

“As researchers, we have to think of a One Health approach: not just prevent cases in people, but also in animals,” says Kozak, who is currently collaborating on a research project to develop a vaccine for both animals and humans.

What is the likelihood of Nipah making its way to North America?

“There has never been a reported case of Nipah virus in Canada since the virus was discovered,” says Kozak, who thinks the likelihood of seeing a Nipah case in Canada and the US is extremely low; so do Carnahan and Rivera.

According to them, Nipah has “a dangerously high fatality rate (40–50 percent, and sometimes more than 70 percent), which may limit its ability to spread globally.” For this reason, and because Nipah virus has a lower transmissibility than Influenza and SARS-CoV-2, it is “unlikely that we would see Nipah in the US in the near future,” wrote the UVMC researchers, cautioning that monitoring a potential threat of Nipah is warranted.

“At the moment, human-to-human contagion is limited. Still, the more outbreaks there are, the more likely the virus could adapt and favor human-to-human transmission, which can lead to larger outbreaks or even epidemics,” explained Carnahan and Ravera.