Amid the coronavirus pandemic that is rampantly spreading across the globe, there has been a surge in unexplained cases of a strange new virus, which was previously found in rats, infecting people with hepatitis in Hong Kong.
Although Hong Kong reported its first case of the mysterious virus in 2018, there has been a recent spike in the number of cases of the unexplained disease across the island that is infecting people with hepatitis E.
Cases of unknown rat virus emerge in Hong Kong
"Suddenly, we have a virus that can jump from street rats to humans," said Dr Siddharth Sridhar, a microbiologist and one of the Hong Kong University researchers who first discovered the disease. At the time, Sridhar and his team though it was a "one-off incident, one patient who was in the wrong place at the wrong time."
Since then, 10 more people have tested positive for the disease, dubbed as rat hepatitis E or rat (HEV), with the most recent case reported a week ago, as reported by CNN. According to Sridhar, there might be hundreds of more people who may have been infected by the disease but still remain undiagnosed.
What is hepatitis E and how deadly is it?
Hepatitis E is a liver disease that is caused by the hepatitis E virus (HEV). The illness can cause fever, jaundice, abnormal liver function and an enlarged liver. The virus has four variants, out of which only one was known to infect humans but now a strain of the virus that previously affected rats has made the jump to human hosts.
The virus can have serious health consequences, particularly for patients with weakened immunity. Young, healthy people with no pre-existing conditions may be able to recover on their own -- but for vulnerable populations, it could cause chronic hepatitis that patients can't recover from, in addition to long-term liver damage and tissue scarring. In some cases, it can even lead to liver failure, which can be fatal, according to the World Health Organization.
How is the rat HEV virus spreading in Hong Kong?
Although hepatitis E is transmitted through faecal contamination of water, infectious disease experts are unable to explain how people in Hong Kong are getting infected with the virus. Researchers are yet to determine exactly how the virus jumped from rats to humans.
While there is the theory that the infected patients may have consumed contaminated water like the usual human strain, or handled contaminated objects, it has not yet been proven. As in the case of the most recent case, a 61-year-old man, authorities have no idea how the patient contracted the virus. Not only was there no presence of rat or rat excrement in his home, other members of his household had not shown any symptoms, and he had no recent travel history.
"Based on the available epidemiological information, the source and the route of infection could not be determined," said Hong Kong's Centre for Health Protection (CHP) in a statement on April 30. "The man is still in the hospital, and the CHP's investigation is ongoing."
Large-scale global outbreak
Worryingly, medication used to treat the virus has been ineffective and not knowing how the virus jumped from rats to humans would make it very difficult to prevent further infections, which could eventually lead to a large-scale outbreak like the ongoing coronavirus pandemic.
"What we know is the rats in Hong Kong carry the virus, and we test the humans and find the virus. But how exactly it jumps between them -- whether the rats contaminate our food, or there's another animal involved, we don't know," said Sridhar. "That's the missing link." According to experts, this is not just a Hong Kong problem. Rat HEV could be infecting people in US or France but we just don't know it because nobody is specifically testing for the infectious disease.
The virus has already started spreading to other parts of the world. In February 2019, a middle-aged Canadian man who had visited Africa was diagnosed with the disease after showing symptoms including nausea, hives, jaundice and an inflamed liver.
"This should not be happening," said Sridhar. "We need ongoing vigilance in the public to control this unusual infection. I really hope that public health authorities take the first step and look at how much their populations are actually being exposed to rat hepatitis E."