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

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 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 scientists said, a finding in line with scientists’ warnings that viruses animals regularly spread undetected. in people all over the world.

“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. . that he was not involved in the latest study.

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.

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

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

Tracking a new virus

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

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

When test samples from this patient 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 ICU. While all have recovered, they were not monitored for long-term problems, he added.

Of that group of 26, 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) 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.

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 thought 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 of which were first detected in the country, and of 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 is 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 nature, how it is spreading to 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 jump from animals to humans.

The geographic range of 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 “in determining 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 does not catch us off guard, when, not if, it arrives,” he said.

Source: www.cnn.com