The henipavirus can cause respiratory symptoms and is related to Nipah and Hendra viruses, but cannot spread easily in people.
Smriti Mallapaty
A new animal virus that can infect people has been identified in eastern China. But scientists say they are not overly concerned because the virus doesn’t seem to spread easily between people, nor is it fatal.
The virus, named Langya henipavirus (LayV), can cause respiratory symptoms such as fever, cough and fatigue, and is closely related to two other henipaviruses known to infect people — Hendra virus and Nipah virus. These also cause respiratory infections, and can be fatal. Researchers think LayV is carried by shrews, which might have infected people directly or through an intermediate animal. The virus was described in the New England Journal of Medicine1 on 4 August.
Researchers say LayV has infected only 35 people since 2018, and none of the cases seems to be linked. “There is no particular need to worry about this, but ongoing surveillance is critical,” says Edward Holmes, an evolutionary virologist at the University of Sydney in Australia. Regularly testing people and animals for emerging viruses is important to understand the risk of zoonotic diseases — those that can be transmitted from other animals to humans, he says.
Large outbreaks of infectious diseases typically take off after a lot of false starts, says Emily Gurley, an infectious-diseases epidemiologist at Johns Hopkins University in Baltimore, Maryland. “If we are actively looking for those sparks, then we are in a much better position to stop or to find something early.”
Hospital surveillance
The research team that identified LayV did so while monitoring patients at three hospitals in the eastern Chinese provinces of Shandong and Henan between April 2018 and August 2021. Participants were recruited into the study if they had a fever.
The team sequenced the LayV genome from a throat swab taken from the first patient identified with the disease, a 53-year-old woman. The virus was named after a town called Langya, in Shandong, where she was from, says co-author Linfa Wang, a virologist at Duke–National University of Singapore Medical School in Singapore.
Throughout the study period, the researchers found 35 people who were infected with LayV, mostly farmers, with symptoms ranging from severe pneumonia to a cough. Most patients said in a questionnaire that they had been exposed to an animal within a month of their symptoms appearing.
The LayV genome shows that the virus is most closely related to Mojiang henipavirus, which was first isolated in rats in an abandoned mine in the southern Chinese province of Yunnan in 2012. Henipaviruses belong to the Paramyxoviridae family of viruses, which includes measles, mumps and many respiratory viruses that infect people. Several other henipaviruses have been discovered in bats, rats and shrews, from Australia to South Korea and China, but only Hendra, Nipah and now LayV are known to infect people.
The researchers did not find strong evidence of LayV spreading between people — there were no clusters of cases in the same family, within a short time span or in close geographical proximity. “Of the 35 cases, not a single one is linked,” says Wang. Gurley says that this is good news, but the study did retrospective contact tracing on only 15 family members of 9 infected individuals, which makes it difficult to determine how exactly the individuals were exposed. Still, she notes that she didn’t see anything in the data to “cause alarm from a pandemic-threat perspective”.
Animal origin
To determine the potential animal origin of the virus, the researchers tested goats, dogs, pigs and cattle living in the villages of infected patients for antibodies against LayV, and took tissue and urine samples from 25 species of wild small animals to look for the presence of LayV RNA. They found LayV antibodies in a handful of goats and dogs, and identified LayV viral RNA in 27% of the 262 sampled shrews. This suggested that shrews are a reservoir for the virus, passing LayV between themselves “and somehow infecting people here and there by chance”, says Gurley.
But it is not clear how people were infected in the first place — whether directly from shrews or an intermediate animal, says Gurley. A lot of research still needs to be done to work out how the virus is spreading in shrews and how people are getting infected, she says.
Holmes says there is an urgent need for a global surveillance system to detect virus spillovers and rapidly communicate those results to avoid more pandemics, such as the one sparked by COVID-19. “These sorts of zoonotic spillover events happen all the time,” he says. “The world needs to wake up.”
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Courtesy: Nature
