Rat Version Of Hepatitis E Detected In A Human For The First Time

Photo: AP

A 56-year-old man from Hong Kong has contracted the rat-specific version of hepatitis E, something never observed before in a human patient. Health officials are now scrambling to understand how this could have happened — and the possible implications.

A medical team from the University of Hong Kong assessed the unnamed patient, who had recently undergone a liver transplant, the South China Morning Post reports.

A human version of hepatitis E exists, which typically spreads through contaminated water. Scientists had previously assumed that the rat version, which is caused by a different virus, is not human-compatible.

The man exhibited unusual and recurrent liver dysfunction following the transplant, the BBC reports, with subsequent tests revealing the presence of a “highly divergent” version of the hepatitis E known to afflict humans.

The scientists in charge of the investigation, Yuen Kwok-yung and Siddharth Sridhar, both from Hong Kong University, aren’t entirely sure how the man contracted hepatitis E, and the case is still under investigation.

It’s highly unlikely that the disease came with the transplanted liver, as there were no signs of the disease in the organ donor, according to SCMP.

The man lives in a subsidised housing complex in eastern Kowloon, which is known to harbour a large rat population. The man lives next door to a garbage chute, where the conditions are generally unclean. It’s possible, say Kwok-yung and Sridhar, that his food supply was contaminated by infected rat droppings.

“You could find rat droppings there,” said Yuen at a press conference held in Hong Kong earlier today. “The drain outlet in the corridor could also allow easy access for rats.”

It’s also possible that the man was bitten by a rat and didn’t notice, but that seems unlikely. The SCMP reports that the man is now “completely normal” following a prescription of ribavirin, an antiviral used for chronic hepatitis E infections.

At the press conference today, the researchers described the discovery as a “wake-up call”, saying local authorities need to improve environmental hygiene in Hong Kong communities and do something about the burgeoning rat population.

“We don’t know if in future there will be a serious outbreak of the rat hepatitis E virus in Hong Kong,” said Kwok-yung. “We need to closely monitor this issue.”

There’s no evidence of an imminent epidemic, the researchers said, but more work is needed to understand how and why the man got infected.

There’s concern, for example, that the virus may have undergone a recent mutation, in which it acquired the capacity to infect humans. Another possibility is that the man’s immune system was compromised after the liver transplant, making him more susceptible to infection, the doctors said.

The full extent of the rat-specific version of hepatitis E is not fully known, aside from what was observed in the patient. The human-specific version of hepatitis E, which is caused by the hepatitis E virus (HEV), is rare in Australia, but it’s quite common in many parts of the world, according to the US Centres for Disease Control.

Humans tend to be infected by ingesting infected faecal matter, such as drinking contaminated water or through contact with poor sanitation. The CDC describes fever, fatigue, loss of appetite, jaundice, and joint pain among the many symptoms.

The health agency says most people recover completely, with mortality rates as low as one per cent. But it’s a different story for pregnant women, for whom hepatitis E infection has a mortality rate between 10 and 30 per cent during the third trimester.

Hepatitis E is rarely chronic, and it typically goes away on its own. Patients diagnosed with the disease are advised to eat nutritious foods, drink plenty of fluids, and avoid alcohol. Pregnant woman are advised to see their doctor, as infections may require a hospital stay.

This is obviously an ongoing story with a lot of missing parts, but it’s certainly cause for concern. As noted, the rat-specific version of hepatitis E may be different than the one known to normally afflict humans, requiring scientists to keep a close watch on the situation. 

[BBC, CNN, SCMP, CDC]

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