The pathogen caused no 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 consistent with long-standing warnings by scientists that animal viruses routinely spread undetected. to people all over the world. “We greatly underestimate the number of these zoonotic cases in the world, and this (Langya virus) is only 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 did not participate in the last study. However, researchers say there is no evidence that the Langya virus is spreading between people or that it has caused a local outbreak of linked cases. More study is needed in a larger subset of patients to rule out human-to-human spread, they added. Veteran emerging infectious disease scientist Linfa Wang, who was part of the research team, told CNN that although the new virus was unlikely to develop into “another ‘disease X’ event,” such as a previously unknown pathogen triggering an epidemic or pandemic. “It turns out 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, “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.
New virus tracking
The first indications of the presence of a new virus emerged when a 53-year-old farmer sought treatment at a hospital in Qingdao city, Shandong province in December 2018 with symptoms including fever, headache, cough and nausea, according to documentation from the researchers. As the patient reported having contact with animals last month, she was enrolled in additional screening conducted at three hospitals in eastern China, focusing on the detection of zoonotic diseases. When this patient’s test samples were examined, scientists found something unexpected — a never-before-seen virus related to Hendra and Nipah viruses, extremely deadly pathogens from a family not typically known for easy human-to-human transmission . Over the next 32 months, researchers at all three hospitals screened similar patients for the virus, eventually finding 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 that the symptoms in the remaining 26 could have been caused by the new henipa virus. Some developed severe symptoms such as pneumonia or abnormalities of thrombocytopenia, a platelet disorder, according to Wang, but their symptoms were very different from Hendra or Nipah patients, and no one in the group died or was admitted to the ICU. Although all recovered, they were not being monitored for long-term problems, he added. Of that group of 26, all but four were farmers, and while some were flagged by the same hospital as the original 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 southwest China to South Korea, it was not “surprising” to see transmission to humans over such long distances, Wang explained. There was “no close contact or shared history of exposure between the patients” or other signs of human-to-human spread, Wang and his colleagues wrote in their findings. That suggested the outbreaks were sporadic, but more research was needed, they said. Once they realized that a new virus was infecting people, the researchers, which included scientists from Beijing and Qingdao disease control officials, set to work to see if they could discover what was infecting the patients. They checked 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 had the virus in the past. But the real breakthrough came when they tested samples taken from small wild animals captured in traps — and found 71 infections in two species of ticks, leading scientists to suggest that these small rodent-like mammals could be there where the virus circulates naturally. What remains unclear is how the virus entered humans, Wang said. Further studies to control the henipa Langya virus will follow and should be conducted not only in the two provinces where the virus was found, but more widely within and outside China, he said. China’s National Health Commission did not immediately respond to a request for comment on whether it was continuing to monitor for new virus infections.
Risk reduction
Globally, 70% of emerging infectious diseases are believed to have passed to humans through contact with animals, a phenomenon scientists say has accelerated as growing human populations expand into 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 identified in the country and from viruses believed to have originated in bats. The devastating effects of both diseases — especially 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 about potential risks. Scientists who were not involved in the new research agreed that more work is needed to understand the Langya virus and confirm the latest findings, and said the discovery underscored the importance of monitoring viruses that may be transmitted from animals to humans. “Because it (the new henipa virus) may not be circulating only in China, it is important to share this information and allow others to prepare or do some further research in their countries,” Poon said in Hong Kong. Scientists say critical questions remain to be answered about how widespread the new virus may be in nature, how it spreads to humans and how dangerous it is to human health — including whether it could spread between humans or acquire that ability if it continues to jump from animals to humans. The geographic range where the infections were found “suggests that this risk of infection is rather widespread,” said virologist Malik Peiris, also of the University of Hong Kong, adding that studies elsewhere in China and neighboring countries were important “for to ascertain the geographical area of this virus in animals (srites) and in humans.” He also said the latest findings hint at the large number of undetected infections transmitted from wildlife to humans and the need for systematic studies to understand not only this virus, but the larger picture of human viral infection from the wild life. “This is important so that we are not caught off guard by the next pandemic when – not if – it comes,” he said.
