From UPSC perspective, the following things are important :
Prelims level : Langya virus
Mains level : Zoonotic Diseases
A new virus, Langya henipavirus, is suspected to have caused infections in 35 people in China’s Shandong and Henan provinces over roughly a two-year period to 2021.
- It’s related to Hendra and Nipah viruses, which cause disease in humans.
- However, there’s much we don’t know about the new virus – known as LayV for short – including whether it spreads from human to human.
How sick are people getting?
- Symptoms reported appeared to be mostly mild – fever, fatigue, cough, loss of appetite, muscle aches, nausea and headache – although we don’t know how long the patients were unwell.
- A smaller 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 investigated whether domestic or wild animals may have been 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 a significant proportion of wild shrews were harbouring the virus.
- This suggests humans may have caught the virus from wild shrews.
Does this virus actually cause this disease?
- The researchers used a modern technique known as metagenomic analysis to find this new virus.
- Researchers sequence all genetic material then discard the “known” sequences (for example, human DNA) to look for “unknown” sequences that might represent a new virus.
- This raises the question about how scientists can tell whether a particular virus causes the disease.
- Researchers used “Koch’s Postulates” to determine whether a particular micro-organism causes disease:
- it must be found in people with the disease and not in well people
- it must be able to be isolated from people with the disease
- the isolate from people with the disease must cause the disease if given to a healthy person (or animal)
- it must be able to be re-isolated from the healthy person after they become ill.
What can we learn from related viruses?
- This new virus appears to be a close cousin of two other viruses that are significant 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 the trainer Vic Rail.
- Nipah virus is more significant globally, with outbreaks frequently reported in Bangladesh.
What lies ahead?
- 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 the virus can spread from human to human.
- Further work is required to determine how severe the infection can be, how it spreads, and how widespread it might be in China and the region.