When scientists published a letter in early August announcing that dozens of people in China had been infected with a little-understood virus, it made headlines more than two and a half years ago.
New nurse. People who develop fever, cough and tiredness. Both humans and animals are infected.
In this case, the message was about the arrival of the Langea hanniba virus, and its possible associations with animal populations, which might call to mind the early days of COVID-19 — or as the virus behind it was then known, the “novel” coronavirus.
“There’s a little bit of introspection here,” said Dr. Ari Bernstein, interim director of the Center for Climate, Health, and Global Environment at Harvard T.H. Chan School of Public Health.
“This is another example of animal-to-person transmission of a pathogen, and as we know, this is the root cause of most emerging infections in the world.”
But when it comes to newly discovered viruses, some cause more concern than others, and not all cases of animal-to-human transmission will result in widespread outbreaks or trigger years-long epidemics. However, many of them are worth pursuing in the scientific world — since more hosts mean more opportunities for the virus to mutate, potentially opening up new avenues of infection, transmission, and spread.
And as many of the scientists who spoke to CBC News agreed, the world should prepare for more viruses like this circulating in humans in the coming years, with Langya only the latest example.
“The fact that there is a virus that has jumped into humans, and that it has evidence of exposure in other species, is really enough information for us to say we should be watching that closely,” Simon Anthony said. Researcher and Associate Professor in the Department of Pathology, Microbiology, and Immunology at the University of California, Davis School of Veterinary Medicine.
No human-to-human transmission has been reported so far
In Lanjia’s case, the virus was identified through observation of people with fever and recent exposure to animals in eastern China.
Scientists based in China published their findings In a letter to the New England Journal of Medicine, In early August, noting that between April 2018 and August 2021, 35 patients infected with the virus were reported in Shandong and Henan provinces, China.
The vast majority of cases were from farmers, who experienced a range of symptoms, including fever, fatigue, cough, nausea, headache and vomiting.
But there are no reports of human-to-human transmission – at least not yet.
There was no close contact or a common history of exposure between the patients, “suggesting that infection in humans may be sporadic,” the researchers wrote.
“Fortunately, in this case, it appears that this virus – at this time – is not easily transmitted between people,” Bernstein said. “So I think we can take a breath here.”
Langia appears to have several animal hosts, primarily shrews. That remains worrisome, said Anthony, who studies emerging viruses and viral evolution.
“The more species they affect, the greater the chance that adaptations will occur. You cannot predict what those adaptations will do.”
Ideally, any random mutations that the virus develops as it bounces between species would not cause harm to humans. Others can make the pathogen more contagious, able to evade the human immune system – as the world has seen through the evolution of SARS-CoV-2 – or even more deadly.
Bernstein stressed that when it comes to Plangia, the number of human cases at the moment is not as worrying as the virus’s apparent ability to spread to different species.
“There are only a few dozen human cases,” he said. “We don’t know if this could get into some kind of pet attachment and cause a lot of animals to get injured… We’re playing roulette here.”
Further repercussions from animal to human are expected
Anthony said the most likely scenario for Langea is that the number of cases remains small, human-to-human transmission fades, and does not lead to a COVID-wide pandemic.
“But also, why are you being silly? Why are you ignoring the information we have in front of us?” question. “And at the very least, more research is needed to understand the potential risks it represents.”
Langia belongs to the family of paramyxoviruses, a group of RNA-based viruses known to mutate fairly quickly.
There have been few documented transmissions of zoonotic infections of paramyx viruses to people in recent years, said Ryan Troyer, a virologist at Western University in London, Ont.
This is in addition to more regular repercussions and Outbreaks associated with Nipah virusIt is a rare, brain-damaging virus in the same family, with a mortality rate of up to 75 percent.
“Other things that happened before COVID-19 didn’t get the same level of attention,” Troyer said. “It’s definitely frustrating that this happens regularly, but I think it’s a relief that it never leads to a major outbreak.”
Under the right conditions, various types of zoonotic viruses have spread throughout the world, from the deadly avian influenza that still persists today primarily among bird populations, to the current global human outbreak of monkeypox that spreads mainly through sexual networks.
Researchers expect more animal-to-human transmission of the virus in the coming years, thanks to factors such as globalization, large-scale development and the ongoing encroachment on animal habitats.
Harvard global health institute review Of the 40,000 species around the world, nearly half are found to be already on the move due to changing climatic conditions.
Bernstein said it is critical to curb climate change and preserve ecosystems in order to prevent viruses from reaching humans in the first place.
“You prevent spread, you protect the habitat … It doesn’t matter what the pathogen is, it’s a uniformly effective approach,” he said.