Translated by Julio Batista
Allen Cheng’s origin of the conversation
It is related to the Hendra and Nipah virus, which cause disease in humans. However, there is a lot we don’t know about the new virus – known as LayV – including whether it spreads from human to human. Here’s what we know so far.
How do people get sick?
Researchers in China first discovered this new virus as part of routine surveillance of people with fever who reported recent contact with animals. Once the virus was identified, researchers looked for the virus in other people.
The symptoms reported appeared to be mostly mild – fever, fatigue, cough, loss of appetite, muscle aches, nausea, headache – although we don’t know for how long the patients were well.
A smaller proportion had 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 have not been reported.
Where did this virus come from?
The authors also investigated whether domestic or wild animals were the source of the virus. While they found a small number of goats and dogs that may have contracted the virus in the past, there was more direct evidence that a large proportion of wild shrews harbored the virus.
This suggests that humans may have contracted the virus from wild shrews.
Does this virus really cause this disease?
The researchers used a modern technique known as metagenomic analysis to find this new virus. Researchers sequence all genetic material and scrap “known” sequences (such as human DNA) to look for “unknown” sequences that could represent a new virus.
This raises the question of how scientists can tell if a particular virus causes disease.
Traditionally, we use “Koch’s assumptions” to determine if a particular microorganism is causing disease:
- It should be found in people with disease and not in healthy people
- You should be able to isolate from people who have the disease
- Virus isolated from infected persons must cause disease if administered to a healthy person (or animal)
- He must be able to re-isolate himself from a healthy person after his illness.
The authors acknowledge that this new virus does not yet meet these criteria, and the importance of these criteria in the modern era has been called into question. However, the authors say they found no other cause of illness in 26 people, with evidence that the immune systems of 14 people responded to the virus and that people who were sick had more viruses.
What can we learn from related viruses?
This new virus appears to be a close cousin to two other viruses important in humans: Nipah virus and Hendra virus. This family of viruses was the inspiration for the fictional MEV-1 virus in the movie Contagion.
Hendra virus was first reported in Queensland, Australia in 1994, when it killed 14 horses and trainer Vic Rail.
Several outbreaks in horses have been reported in Queensland and northern New South Wales since then, and are generally believed to be caused by a ‘cross’ infection of flying foxes.
In total, seven human cases of Hendra virus infection have been reported in Australia (mostly veterinarians working with sick horses), including four deaths.
The Nipah virus is considered the most significant globally, with outbreaks frequently reported in Bangladesh.
The severity of the infection can range from very mild encephalitis to fatal encephalitis (encephalitis).
The first outbreaks were reported in Malaysia and Singapore in people who had close contact with pigs. However, the most recent outbreaks are believed to have occurred due to food contaminated with urine or saliva from infected bats.
Remarkably, the Nipah virus appears to be transmitted from person to person, primarily between household contacts.
What do we need to know next?
Little is known about this new virus, and the currently reported cases are likely the tip of the iceberg.
At this point, there is no indication that the virus can spread from human to human.
More work is needed to determine the severity of the infection, how it is spread, and how widespread it is in China and the region.
Allen Cheng is Professor of Infectious Diseases Epidemiology at Monash University.