The woman was admitted to a public hospital on May 4, 2017, for a headache, anorexia, malaise, abdominal pain and palpitations, which she had developed 3 days back. She was discharged four days later, on May 8 after recovery. The woman had underlying illnesses, according to the Department of Health.
After the first case of this disease, the Centre for Health Protection of the Department of Health provided blood samples from patients who had tested positive for an immune protein called anti-HEV immunoglobulin — a sign someone is infected with hepatitis E, known as HEV. Further investigations by Hong Kong University detected elements of DNA evident of rat HEV. This is how the new case of the 70-year-old woman was identified.
Genetic sequencing results show the viruses in both cases to be highly similar, wrote Dr Yh Leung, senior medical and health official from the Centre for Health Protection, in the Department of Health’s newsletter Thursday.
“Rat hepatitis E virus now joins this list of infections as an important pathogen that may be transmitted from rats to humans,” Dr Siddharth Sridhar, clinical assistant professor at the University of Hong Kong, previously said, adding that the risk of rat hepatitis E affecting humans has been underestimated.
The Centre for Health Protection’s investigation showed that the two people with hepatitis E infections caused by rats had no travel history during the virus’ usual incubation period of two to 10 weeks. Both the 56-year-old man and the 70-year-old woman resided in Hong Kong’s Wong Tai Sin District, just over a mile apart. There are no other findings hinting at epidemiological links between the two cases, Leung wrote.
The apparent clustering of the two cases is of concern, and the Centre for Health Protection will continue to closely monitor the situation, Leung wrote, adding that the sources and routes of the infections could not be determined.
“It is likely that the virus can be found commonly in rats, with one study in Vietnam suggesting that more than 10% of them may have been infected,” Martin Hibberd, professor of emerging infectious diseases at the London School of Hygiene & Tropical Medicine, wrote in an email. “Infection can be acquired by close contact with rats, or perhaps more likely through rat contaminated food or water.”
Hong Kong’s Public Health Laboratory Services Branch has implemented a molecular test targeting different hepatitis E viruses and will use this to test cases testing positive for anti-HEV immunoglobulins.
The public is advised to practice food safety, such as keeping hands and utensils clean, cooking thoroughly and keeping food at a safe temperature to prevent future infections, the letter adds.
Additonal specific food safety suggestions include choosing safe raw materials, keeping hands and utensils clean, separating raw and cooked food, keeping food at a safe temperature and cooking thoroughly.
The animal form of the disease is thought to infect wild boars, domestic pigs and deer, as well as rats and other rodents.
Hepatitis E is found worldwide, but the prevalence is highest in East and South Asia. A vaccine to prevent hepatitis E virus infection has been developed and is licensed in China, but is not yet available elsewhere.