Rat Hepatitis E: a ‘wake-up call’ for Hong Kong to shape up on public hygiene after man, 56, becomes world’s first person infected with virus
Top HKU microbiologist investigating the case says more time needed to understand why man was infected with virus previously found only in rats and ferrets
Hong Kong has been put on notice to shape up on public hygiene and get rid of rodents, after a male resident became the first person in the world to be infected with a strain of Hepatitis E previously found only in animals such as rats.
The 56-year-old who lives in a public housing estate in eastern Kowloon underwent liver transplant surgery in May last year and was tested for the virus after he displayed recurring liver function problems.
Professor Yuen Kwok-yung, a top microbiologist at Hong Kong University, told a press conference on Friday that the discovery was a “wake-up call” to improve environmental hygiene and prevent rats from breeding.
“We don’t know if in future there will be a serious outbreak of the rat Hepatitis E virus in Hong Kong,” he said. “We need to closely monitor this issue.”
He said the city’s streets were very clean after the deadly outbreak of the Severe acute respiratory syndrome (Sars) in 2003, but public cleanliness appeared to have slipped recently.
“Back alleys now are very dirty with lots of rubbish. You can see rats that are bigger than cats,” Yuen said.
He led the team that had studied the patient for the past year and revealed initial information about the case on Thursday. He also informed authorities, including the Food and Environmental Hygiene Department, which responded with a clean-up operation at Choi Wan estate where the man lives on Friday.
There is no evidence of an imminent major epidemic following the discovery of rat Hepatitis E in the patient, assured Dr Siddharth Sridhar, a clinical assistant professor from HKU’s department of microbiology involved in studying the patient.
But researchers took any new incidence of infections jumping from animals to humans very seriously.
“These kinds of unusual infections, rare infections, first instances – even one case is enough to make public health authorities and researchers very alert about the implications,” he said.
In this case, effective rodent control was key in preventing similar infections.
“Ensure there is no food for the rats, which means there is no garbage lying around that the rats can feed on,” Sridhar said.
Yuen said the patient’s condition is now “completely normal” after he was treated with ribavirin, an antiviral medication for chronic hepatitis E infections.
However, it is still not known yet how the man got infected.
Yuen said the man had a liver transplant at HKU’s Queen Mary teaching hospital in May last year, but there were no signs of hepatitis E infection in the organ donor or those who donated blood to the patient.
The researchers thought it possible that the man might have consumed contaminated food infected by rat droppings.
But the rodent infestation rate in Wong Tai Sin, near his home, was not very high last year, and Yuen wondered aloud: “Was the patient infected after being bitten by a rat without noticing?”
He said researchers needed more time to understand why the man was infected with a virus that previously only affected rats and ferrets.
He said: “Was it because after a period of time, genetic changes of the virus in the rats were sufficient enough to infect a human?”
It was also possible that the patient was more susceptible to infection because his immune system was weakened after the organ transplant.
Researchers visited the man’s home and found that his flat was next to a refuse chute, where hygiene conditions were poor.
“You could find rat droppings there,” said Yuen. “The drain outlet in the corridor could also allow easy access for rats.”
He said the environment provided favourable conditions for rats to breed.
Rodent droppings, swabs from the refuse room’s drain and floor, and previously collected rat samples in the area were tested for the virus. But only frozen samples from a rat collected by hygiene authorities in the district in 2012 were found to be infected.
The authorities on Friday responded to Yuen’s call for stepped-up action against rats by promising to do more to raise awareness of the need for good hygiene at home and in the estate.
A spokesman for the Housing Department said there had been no complaints in the past few months about rats at Choi Wan Estate although residents there said they had seen rats scurrying around in apartment blocks and in the ground-floor refuse collection area.
The Food and Environmental Hygiene Department said it would hold a roadshow about cleaning operations on October 3, together with the Home Affairs Department.
A spokesman for the Food and Environmental Hygiene Department said it had received 263 complaints of rodent problems in Wong Tai Sin last year, and 148 complaints in the same district in the first eight months of this year. The department said it conducted daily rodent control work, including street cleaning, poisoning and trapping rats and blocking rat holes.
From October 8 to December 7, it would hold its second citywide anti-rodent campaign and department officers had already given suggestions on how to prevent infestations to the Housing Department office in Choi Wan estate, it said.
Five viruses that can cause Hepatitis in people
Hepatitis is an inflammation of the liver. In most cases, it is caused by viruses but can sometimes be caused by alcohol, drugs, chemicals or genetic diseases, though this is less common. There are five main hepatitis viruses – A, B, C, D, and E – that are of greatest concern to doctors because they can cause epidemics and death.
Hepatitis A: Present in the faeces of infected persons and most often transmitted through consumption of contaminated water or food, but also through sex practices. Infections in many cases are mild with most people making a full recovery and remaining immune to further infection.
Hepatitis B: Transmitted through exposure to infected blood, semen and other body fluids. There are vaccines to prevent it.
Hepatitis C: Mostly transmitted through exposure to infected blood. There is no vaccine for the virus.
Hepatitis D: Occurs only in those who have the Hepatitis B virus, but the dual infection can result in a more serious disease. Hepatitis B vaccines provide protection from the Hepatitis D virus.
Hepatitis E: Mostly transmitted through consumption of contaminated water or food. Hepatitis E is a common cause of virus outbreaks in the developing world; safe and effective vaccines to prevent infection have been developed but are not widely available.
Sources: World Health Organisation; Hong Kong Department of Health