New Langya virus found in China could be just the 'tip of the iceberg', researchers warn

An Ussuri white-toothed shrew.

Scientists in China have detected a new virus in the species.

Hong Kong (CNN) --

A new virus detected in dozens of people in eastern China may not cause the next pandemic, but it does suggest how easily viruses can slip from animals to humans, scientists said, warning that it is more vigilance is needed.

The virus, called Langya henipavirus, has infected nearly three dozen farmers and other residents, according to a team of scientists who believe it may have spread directly or indirectly to people through 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 scientists said.

This finding is in step with warnings from scientists that animal viruses are regularly spreading undetected in people around the world.

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"We are grossly underestimating the number of these zoonotic cases in the world, and this (Langya virus) is just the tip of the iceberg," said emerging virus expert Leo Poon, a professor at the University of Hong Kong's School of Public Health. , who was not involved in the latest study.

The first scientific research on the virus, published as correspondence by a team of Chinese and international researchers in the New England Journal of Medicine last week, has received global attention amid heightened concern about disease outbreaks.

Hundreds of thousands of new cases of covid-19 are still being reported around the world every day, nearly three years since the novel coronavirus behind the current pandemic was first detected in China.

However, the researchers say there is no evidence that the Langya virus is spreading between people or has caused a local outbreak of connected cases.

Further studies on a larger subset of patients are needed to rule out person-to-person spread, they added.

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Veteran emerging infectious disease scientist Linfa Wang, who was part of the research team, told CNN that while the new virus was unlikely to evolve into "another 'disease X' event," such as a previously unknown pathogen that triggers an epidemic or pandemic, "demonstrates that such secondary zoonotic events occur more frequently than we think or know".

To reduce the risk of an emerging virus turning into a health crisis, "it is absolutely necessary to carry out active surveillance in a transparent and collaborative way at the international level," said Wang, a professor at the National University of Medicine School of Medicine. Duke of Singapore.

Following the trail of a new virus

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

As the patient indicated that she had had contact with animals in the last month, she was enrolled in further evaluation being carried out in three hospitals in eastern China to identify zoonotic diseases.

When this patient's test samples were examined, scientists found something unexpected: a virus that had never been seen before, related to Hendra and Nipah viruses, highly deadly pathogens from a family not usually known for their easy spread of bacteria. Person to person.

Over the next 32 months, researchers at the three hospitals tested similar patients for this virus, eventually detecting it in 35 people, who had a range of symptoms including cough, fatigue, headache and nausea, as well as fever.

Nine of those patients were also infected with a known virus, such as influenza, so the source of their symptoms was unclear, but the researchers believe the 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 blood platelet condition, according to Wang, but their symptoms were a far cry from those seen in Hendra or Nipah patients, and no one in the group died or was admitted to the unit. of intensive care.

While all have recovered, they were not monitored for long-term problems, she added.

Of that group of 26, all but four were farmers, and while some were flagged by the same hospital as the initial detected case, 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 it spread to humans over such long distances, Wang explained.

There was no "close contact or common exposure history among patients" or other signs of person-to-person spread, Wang and colleagues wrote in their findings.

This suggests that the cases were sporadic, but more research is needed, they said.

Once they learned that a new virus was infecting people, the researchers, including Beijing-based scientists and Qingdao disease control officials, went to work to see if they could figure out what was infecting patients.

They examined domestic animals where the patients lived for traces of past infections with the virus, and found a small number of goats and dogs that may have previously had the virus.

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

What is not clear is how the virus got to people, Wang said.

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

China's National Health Commission did not immediately respond to a request for comment on whether monitoring for new virus infections was ongoing.

risk reduction

Globally, 70% of emerging infectious diseases are believed to have passed to humans through contact with animals, in a phenomenon that scientists say has accelerated as burgeoning human populations expand into the world. wildlife habitats.

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

The devastating effects of both diseases, in particular covid-19, which to date has killed more than 6.4 million people worldwide, demonstrate the importance of quickly identifying cases of new viruses and sharing information about them. the potential risks.

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

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

Scientists say critical questions need to be answered about how widespread the new virus may be in the wild, how it is spreading to people and how dangerous it is to human health, including the potential for it to spread between people or acquire this ability if you continue to jump from animals to humans.

The geographic range where the infections were found "suggests that this risk of infection is quite widespread," said virologist Malik Peiris, also of the University of Hong Kong, adding that studies in other parts of China and neighboring countries were important. "to determine the geographic range of this virus in animals (shrews) and in humans".

He also said the latest findings hinted at the large number of undetected infections being transmitted from wildlife to people, and the need for systematic studies to understand not just this virus, but the broader picture of human infection with viruses. of wildlife.

"This is important so that the next pandemic doesn't catch us off guard when it arrives," he said.