Langya henipavirus: New virus found in China may be ‘tip of iceberg’ for undiscovered pathogens, researchers say

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Hong Kong

More monitoring is needed of a new virus discovered in dozens of people in eastern China that may not cause the next pandemic but suggests how easily viruses can travel unnoticed from animals to humans, scientists say.

The virus, called Langya henipavirus, infected nearly three dozen farmers and other residents, according to a team of scientists who believe it may have spread directly or indirectly to humans from shrews – small mole-like mammals found in a wide variety of habitats.

The pathogen did not cause any reported deaths, but was detected in 35 unrelated fever patients in hospitals in Shandong and Henan provinces between 2018 and 2021, the researchers said — a finding consistent with long-standing warnings by scientists that animal viruses regularly spill over undetected in people around the world.

“We vastly underestimate the number of these zoonotic cases in the world, and this (Langya virus) is only the tip of the iceberg,” said new virus expert Leo Poon, a professor at the University of Hong Kong’s School of Public Health. who were not involved in the latest study.

The first scientific research on the virus, published as a correspondence by a team of Chinese and international researchers in the New England Journal of Medicine last week, gained global attention amid heightened concern about disease outbreaks. Hundreds of thousands of new Covid-19 cases are still being reported around the world every day, almost three years since the novel coronavirus behind the pandemic was first discovered in China.

However, the researchers say there is no evidence that the Langya virus is spreading between people or that it had caused a local outbreak of linked cases. More studies of a larger subset of patients are needed to rule out human-to-human spread, they added.

Veteran new infectious disease researcher Linfa Wang, who was part of the research team, told CNN that while the new virus was unlikely to develop into “another ‘disease X’ event,” such as a previously unknown pathogen that triggers an epidemic or pandemic , “It shows that such zoonotic spillover events happen more often than we think or know.”

To reduce the risk of a new virus turning into a health crisis, “it is absolutely necessary to conduct active surveillance in a transparent and internationally cooperative manner,” said Wang, a professor at the Duke-National University of Singapore Medical School.

The first clues to the presence of a new virus emerged when a 53-year-old farmer sought treatment at a hospital in Shandong province’s Qingdao city in December 2018 with symptoms including fever, headache, cough and nausea, according to documentation from researchers.

Since the patient indicated that she had contact with animals within the past month, she was enrolled in additional screening conducted across three hospitals in eastern China with a focus on identifying zoonotic diseases.

When this patient’s test samples were examined, the researchers found something unexpected—a virus that had never been seen before, related to Hendra and Nipah viruses, highly lethal pathogens from a family not typically known for easy human-to-human transmission dispersion.

Over the next 32 months, researchers across the three hospitals screened for this virus in similar patients, ultimately discovering it in 35 people who had a range of symptoms including cough, fatigue, headache and nausea, in addition to fever .

Nine of these patients were also infected with a known virus, such as influenza, so the source of their symptoms was unclear, but researchers believe that symptoms in the remaining 26 could have been caused by the new henipavirus.

Some showed severe symptoms such as pneumonia or abnormalities of thrombocytopenia, a platelet condition, according to Wang, but their symptoms were far from those seen in Hendra or Nipah patients, and no one in the group died or was admitted to the intensive care unit. While all recovered, they were not monitored for long-term problems, he added.

Of this group of 26, all but four were farmers, and while some were flagged by the same hospital where the first case was discovered, many others were found in Xinyang, more than 700 kilometers (435 miles) away in Henan.

Because similar viruses were known to circulate in animals from southwestern China to South Korea, it was “not surprising” to see transmission to humans occurring over such long distances, Wang explained.

There was “no close contact or shared exposure history among the patients” or other evidence of human-to-human spread, Wang and his colleagues wrote in their findings. This suggests that cases were sporadic, but more research was needed, they said.

Knowing that a new virus was infecting humans, the researchers, who included Beijing-based scientists and Qingdao disease control officials, set out to see if they could uncover what was infecting the patients. They tested domesticated animals where patients lived for traces of previous infection with the virus and found a small number of goats and dogs that may have previously had the virus.

But the real breakthrough came when they tested samples taken from small wild animals caught in traps – and found 71 infections across two shrew species, leading the researchers to suggest that these small, rodent-like mammals could be where the virus naturally circulates.

What remains unclear is how the virus entered humans, Wang said.

Further studies, screening for Langya henipavirus will follow and should be carried out not only in the two provinces where the virus was found, but more broadly in China and beyond, he said.

China’s National Health Commission did not immediately respond to a request for comment on whether surveillance for new infections of the virus was underway.

Globally, 70% of new infectious diseases are thought to have passed to humans via contact with animals, in a phenomenon scientists say has accelerated as growing human populations expand into wildlife habitats.

China has seen major outbreaks of new viruses in the past two decades, including SARS in 2002-2003 and Covid-19 – both first discovered in the country and from viruses believed to have originated in bats.

The devastating effects of both diseases – especially Covid-19, which has killed more than 6.4 million people worldwide to date – show the importance of identifying cases of new viruses quickly and sharing information about potential risks.

Scientists not involved in the new research agreed that more work was needed to understand the Langya virus and confirm the latest findings, and said the discovery underscored the importance of tracking which viruses can spread from animals to humans.

“Because this (new henipavirus) may not be circulating only in China, it is important to share this information and allow others to prepare or conduct further investigations in their own countries,” Poon said in Hong Kong.

Scientists say critical questions need to be re-answered how widespread the new virus may be in nature, how it infects humans and how dangerous it is to human health – including the potential for it to spread between humans or gain this ability if it continues to jump from animals to humans.

The geographic range of where the infections have been found “suggests that this risk of infection is quite widespread,” said virologist Malik Peiris, also of the University of Hong Kong, adding studies elsewhere in China and neighboring countries were important “to establish the geographic area of ​​this virus in the animals (shrews) and in humans.”

He also said the latest findings suggested the large number of undetected infections that cross from wildlife to humans, and the need for systematic studies to understand not just this virus, but the broader picture of human infection with viruses from wild animals.

“This is important so that we are not caught unawares by the next pandemic when – not if – it comes,” he said.

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