World’s second case of rat hepatitis E in humans reported in Hong Kong, two months after local resident revealed as first patient
- Patient, 70, is a retiree who lived in the Wong Tai Sin district, the same area as man in previous case
- Expert says both infections are not linked despite two locations being only 3km apart
A 70-year-old Hong Kong woman was revealed on Monday to be the world’s second case of rat hepatitis E infection in humans, two months after another local resident living 3km (1.9 miles) away was reported as the first patient.
Secretary for Food and Health Sophia Chan Siu-chee said hours after the news broke that she was very concerned about the emergence of the second case. A local expert involved in the investigation said it was not linked to the first infection despite both patients living in the same district.
Dr Siddharth Sridhar, clinical assistant professor from the University of Hong Kong’s department of microbiology, said the second case proved that the rat hepatitis E virus, which was distantly related to human hepatitis E virus variants, could be transmitted to people.
“If a patient’s immunity is weak, he or she could get infected with this virus,” Sridhar said, but added that there was no need for panic as the case happened last year.
While Chan said rat control measures had been stepped up in Wong Tai Sin, Sridhar suggested that laboratories should conduct specific testing on samples from hepatitis patients to see if the infections were rat-borne.
The Department of Health confirmed that the second patient was a retiree with underlying illnesses and a suppressed immune system. It said the woman had developed symptoms including abdominal pain, loss of appetite and malaise since May 1 last year, and was admitted to Kwong Wah Hospital in Yau Ma Tei on May 4. She was discharged four days later and had recovered.
The patient’s blood sample collected during her hospital stay and analysed in HKU labs was later found to be carrying the rat hepatitis E virus. The university reported its findings to the department’s Centre for Health Protection earlier this month.
The woman, who lived in Wong Tai Sin Disciplined Services Quarters, did not recall having direct contact with rodents and their excreta, or noticing rats in her home.
“Based on the available epidemiological information, the source and the route of infection could not be determined,” a spokesman for the department said.
But Sridhar said it was possible the woman came into contact with rodents unknowingly.
“Not seeing did not mean there was no contact,” Sridhar said. “It was possible that rodents’ excreta somehow got into food which the patient ate.”
In late September, Hong Kong reported the world’s first case of a human infected with the rat hepatitis E virus. The first patient was a 56-year-old man living in Choi Wan Estate in Kowloon. He underwent liver transplant surgery in May last year, and had developed persistent abnormal liver function two months later.
The home of the woman in the second case was about 3km away from that of the man.
But Sridhar said current evidence did not show direct links between the two patients.
While there was no academic literature on human-to-human transmission of rat hepatitis E, Sridhar said theoretically a person with a weak immune system could be infected by another person carrying the virus.
The Centre for Health Protection had already informed the pest control advisory section of the Food and Environmental Hygiene Department about the case and urged it to carry out rodent control measures where appropriate.
Wong Tai Sin district councillor Bee Lee Tung-kong said rodents were not an apparent issue around the residential complex where the second patient lived, and he had received no previous complaints on the matter.
“What I’m worried about is that we still don’t know the whereabouts of the sources of infection [for both patients]. These sporadic cases could cause public panic,” Lee said, added that it was possible more infections could surface later.
The Food and Environmental Hygiene Department said its officers had conducted inspections in areas near the second patient’s home, such as at public housing estates, shopping malls and schools.
“According to the department’s preliminary inspection, some of those places had mild rodent infestation issues,” a department spokesman said. He added that in response to the latest case, control measures were also stepped up in the areas.
The department last year caught more than 14,000 live rats and poisoned over 26,000 in Hong Kong.
The hepatitis E virus is one of five strains. It is transmitted through various routes, including the consumption of drinking water contaminated by faeces of carriers, and eating undercooked meat.
Meanwhile, some residents of Wong Tai Sin Disciplined Services Quarters and nearby blocks said they were surprised by the news, adding they were generally satisfied with the hygiene of the neighbourhood.
On Monday evening, it was business as usual in the area, and there were no signs of any special cleaning operations, according to those living there.
One resident said: “Probably it’s an isolated case. I find the hygiene of the blocks here rather OK. I have lived here for more than three years and I haven’t seen one rat.”
Issac Yip, a resident of nearby luxury residential complex Lions Rise, said: “Occasionally, you may see a rat in the park opposite. But it shouldn’t be a big deal. And the Food and Environmental Hygiene Department people conduct rat preventive operations regularly.”
The quarters are located on Sha Tin Pass Road in Wong Tai Sin. It is opposite the public Lower Wong Tai Sin Estate.
Visitors at Muk Lun Street Playground, a public park across the road, also said they were satisfied with cleanliness there.
Additional reporting by Danny Mok and Ng Kang-chung