After Covid-19, monkeypox and poliomyelitis, a new virus has just made its entry with great fanfare onto the international scientific (and media) scene. According to the media Taïpei Times several dozen people located in the Chinese provinces of Shandong and Henan have indeed contracted a “new virus” of animal origin, called “Langya”.
According to the Taiwanese health authorities, the Langya henipavirus (LayV) virus causes symptoms in humans such as fever, fatigue, cough, nausea and headache. Something to obviously recall the symptoms of Covid-19. And yet, according to the first elements collected by scientists, this virus cannot, for the time being, be compared to SARS-CoV-2, responsible for the epidemic. of Covid-19. We explain why.
A virus detected in 2018
Let’s rewind. On August 4, the medical journal New England Journal of Medicine (NEJM), a reference journal in the United States, publishes a report with the evocative title: “A zoonotic Henipavirus [découvert] in patients in China”. Quickly, the international press, and in particular Taiwanese, echoed this report with its so familiar sounds. Because, almost three years ago, the Covid-19, then still simply called “coronavirus”, was also presented as an emerging disease very probably transmitted by an animal. For a time (heavily) incriminated, the pangolin had finally given up its place as a “reservoir” to the bat, without any link having yet been formally established today between the small chiroptera and the origin of the Covid- 19.
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In the case of Langya henipavirus, the zoonotic track is again preferred. Scientists assume that the shrew, a small mammal with a pointed snout, is the animal that allowed the transmission of the virus to humans. But can we then compare, in view of their probable similar origin, SARS-CoV-2 to Langya henipavirus? And is such a similarity a harbinger of an epidemic to come?
The answer lies in the numbers. Because in reality, if the daily Taïpei Timeswhich relayed the NEJM study, indicates the exact number of people infected with the virus, that is to say 35 to date, it omits essential information: these 35 cases have been identified and taken into account. charge from April 2018 to August 2021, and each of these cases had animal exposure in the month prior to symptom onset.
In short: nothing to do, for the moment, with the Covid-19 which has spread like wildfire in the space of a few months.
“At this stage, with 35 cases [de] identified in three years, there is no heavy traffic and all this has nothing to do with the Covid-19 […] Each year, several viruses emerge in humans without causing epidemics. It has been circulating quietly for several years and we are not in an emergency situation as was the case with SARS-CoV-2. There are no particular concerns at this stage, but the need for further studies”explains Yannick Simonin in the columns of the Parisian .
Human-to-human transmission ruled out for now
Another important point: at the antipodes of Covid-19, scientists rule out at this stage the risk of human-to-human transmission of Langya henipavirus. According to Professor François Balloux of the UCL Genetics institute, the Langya “does not spread rapidly in humans”as evidenced by the few cases reported over the past three years.
Moreover, in their report published by the NEJM, the scientists explain that the patients, mostly farmers, had neither “close contact” in “joint exhibition” to a pathogenic agent, thus assuming an infection “sporadic” in humans.
“If there is no human-to-human transmission, it is difficult to imagine a real epidemic because not everyone is exposed to shrews”comments François Balloux.
No serious or fatal cases
In addition, no serious or fatal cases of Langya have been identified so far, underlines with the Global Times virologist Linfa Wang, of the Duke-NUS School of Medicine in Singapore, one of the authors of the report.
In detail, in the 26 patients studied (out of 35 identified in total), 100% had fever, 54% fatigue, 50% cough and anorexia, 46% muscle pain, 38% nausea, 35% headache, vomiting and abnormal thrombocytopenia (heavy bleeding), 54% a decrease in the number of white blood cells, 35% liver failure and 8% kidney failure.
According to researchers from China, Singapore and Australia who helped write the report, further research is therefore needed to better understand the illnesses associated with the virus.
Most, “at this stage, the Langya henipavirus does not look like a repeat of Covid-19 at all”, emphasizes François Balloux. However, “it is yet another reminder of the imminent threat caused by the many pathogens circulating in wild and domestic animal populations that have the potential to infect humans”.