A new virus, Langya henipavirus, is suspected to have infected 35 people in China’s Shandong and Henan provinces while the world is still battling the outbreak of COVID-19. It is related to Hendra and Nipah viruses, which cause disease in humans. However, we don’t know much about the new virus, known as LayV, including whether it spreads from human to human. Here’s what we know so far:
How sick are people getting?
Researchers in China first detected the new virus as part of routine surveillance in people with fever and recent exposure to animals. Once the virus was identified, the researchers looked for the virus in other people. Reported symptoms mostly seem to be mild fever, fatigue, cough, loss of appetite, muscle aches, nausea, and headache. Although the timing of recovery is still a mystery.
A small proportion had potentially more serious complications, including pneumonia, and abnormalities in liver and kidney function. However, the severity of these abnormalities, the need for hospitalization, and whether any cases were fatal were not reported.
Where did this virus come from?
The authors also examined whether domestic or wild animals could be the source of the virus. Although they found a small number of goats and dogs that may have been infected with the virus in the past, there was more direct evidence that a significant proportion of wild roosters were harboring the virus. This suggests that humans may have caught the virus from wild snares.
Does this virus really cause this disease?
Researchers used a modern technique known as metagenomic analysis to find this new virus. Researchers sequence all genetic material and then discard known sequences (for example, human DNA) to look for unknown sequences that may represent a new virus. This raises the question of how scientists can tell whether a particular virus causes disease.
We have traditionally used Koch’s postulates to determine whether a particular microbe causes disease:
-It should be found in people with disease and not in good people
-It must be able to be distinguished from people with the disease
If given to a healthy person (or animal), the disease must arise when it is separated from the people suffering from the disease.
A healthy person should be able to re-isolate after he or she becomes ill.
The authors acknowledge that this new virus does not yet meet these criteria, and the relevance of these criteria in the modern era has been questioned. Although the authors say they found no other cause of illness in 26 people, there was evidence that the immune systems of 14 had responded to the virus, and those who were more unwell had more virus.
What can we learn from the related virus?
This new virus appears to be a close relative of two other viruses that are important in humans: Nipah virus and Hendra virus. This family of viruses was the inspiration for the fictional MEV-1 virus in the film Contagion.
Hendra virus was first reported in Queensland in 1994, when it caused the deaths of 14 horses and trainer Vic Rail. Several outbreaks in horses have been reported in Queensland and northern New South Wales, and are generally thought to be caused by spillover? Infection from flying foxes.
In total, seven human cases of Hendra virus have been reported in Australia (mostly by veterinarians working with sick horses), including four deaths.
Nipah virus is more important globally, with outbreaks often occurring in Bangladesh. The severity of the infection can range from very mild to fatal encephalitis (inflammation of the brain).
The first outbreaks in Malaysia and Singapore were reported in people who had close contact with pigs. However, it is believed that recent outbreaks have been caused by food contaminated with the urine or saliva of infected bats.
Significantly, Nipah virus appears to be spread from person to person, mostly among household contacts.
Langya virus: can it spread to humans? Know all the symptoms, causes
What do we have to find out next?
Little is known about this new virus, and the currently reported cases are likely to be the tip of the iceberg. At this stage, there is no indication that the virus can spread from human to human. Further work is needed to determine how severe the infection can be, how it spreads, and how widespread it may be in China and the region.