Langya henipavirus: New virus discovered in China could be 'tip of the iceberg' for undiscovered pathogens, researchers say

Langya henipavirus: New virus discovered in China could be ‘tip of the iceberg’ for undiscovered pathogens, researchers say

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The virus, dubbed 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 of shrews – small mole-like mammals found in a wide variety of habitats.

The pathogen has not caused any reported deaths, but was detected in 35 patients with unrelated fever in hospitals in Shandong and Henan provinces between 2018 and 2021, the scientists said – a finding in line with the long-standing warnings from scientists that animal viruses regularly spread undetected. in people all over the world.

“We hugely underestimate the number of these zoonotic cases around the world, and this (Langya virus) is just the tip of the iceberg,” said emerging virus expert Leo Poon, a professor at the School. of Public Health from the University of Hong Kong, which was not involved in the latest study.

However, the researchers say there is no evidence that the Langya virus spreads between people or has caused a local outbreak of connected cases. Further studies on a larger subset of patients are needed to rule out human-to-human spread, they added.

Linfa Wang, a veteran emerging infectious disease scientist who was part of the research team, told CNN that while the novel virus was unlikely to progress to “another ‘disease X’ event,” as a previously unknown pathogen that triggers an epidemic or pandemic, “This demonstrates that such zoonotic spillover events occur more often than we think or know.”

In order to reduce the risk of an emerging virus becoming a health crisis, “there is a strong need to conduct active surveillance in a transparent and collaborative manner internationally,” said Wang, a professor at Duke-National University of Singapore Medical. School.

Track down a new virus

According to the documentation of the researchers.

As the patient indicated that she had contact with animals in the past month, she was enrolled in additional screening conducted at three hospitals in eastern China focused on identifying zoonotic diseases.

When this patient’s test samples were examined, scientists discovered something unexpected – a virus that had never been seen before, related to the Hendra and Nipah viruses, highly deadly pathogens in a family that is generally not known for its easy human-to-human spread.

Over the next 32 months, researchers at the three hospitals screened for this virus in similar patients, eventually detecting 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 the researchers believe the symptoms in the other 26 could have been caused by the new henipavirus.

Some had severe symptoms like pneumonia or abnormalities of thrombocytopenia, a blood platelet disease, 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 intensive care. Although all have recovered, they have not been monitored for longer-term issues, he added.

Of this group of 26 people, all but four were farmers, and while some were reported by the same hospital as the initial case detected, many others were found in Xinyang, more than 700 kilometers (435 miles) in the Henan.

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

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

Once they learned a new virus was infecting people, the researchers, who included Beijing-based scientists and Qingdao disease control officials, set to work to see if they could find out what was infect patients. They tested pets where patients lived for traces of past infection with the virus, and found small numbers of goats and dogs that may have had the virus previously.

But the real breakthrough came when they tested 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, tree-like mammals rodents could be where the virus naturally circulates.

What remains unclear is how the virus got into people, Wang said.

Further screening studies for Langya henipavirus will follow and should be conducted not only in the two provinces where the virus was found, but more widely in 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 underway.

Risk reduction

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

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

The devastating effects of the two diseases – particularly Covid-19 which has so far killed more than 6.4 million people worldwide – demonstrate the importance of quickly identifying cases of new viruses and sharing information on the 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 viruses that could 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 investigation in their own country,” said Poon in Hong Kong.

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

The geographic extent of where the infections were found “suggests that this infection risk is quite widespread,” said virologist Malik Peiris, also from the University of Hong Kong, adding that studies elsewhere in China and in neighboring countries were important “in determining the geographical scope”. of this virus in animals (shrews) and in man.”

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

“It’s important so that we’re not caught off guard by the next pandemic, when — not if — it happens,” he said.

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