Some of the rise in hepatitis E infections in Singapore may be linked to eating undercooked pork, according to a study.

The research led by the Singapore General Hospital (SGH) found that incidence of hepatitis E (HEV) had increased from 1.7 cases per 100,000 residents in 2012 to 4.1 cases per 100,000 residents in 2016. The work was published in the journal Zoonoses and Public Health.

In developed Asian countries, HEV strains detected in humans and food sources were genetically similar, suggesting that indigenous HEV infections may be largely foodborne.

HEV subtyping was done on 59 of 449 patient blood samples collected between 2014 and 2016. Forty four of these 59 samples showed that the strain belongs to HEV genotype 3a, which was the same type detected in three of 36 raw pork liver samples purchased from wet markets and supermarkets.

“Although we could not ascertain if pig liver is the main contributor of HEV cases in Singapore, we observed that pig liver can be found in many local dishes,” said Dr. Chan Kwai Peng, senior author of the study and senior consultant in the Department of Microbiology at SGH.

“As most people like it a little undercooked for its texture, this may put them at risk of hepatitis E infection. The safest way of consuming food, including pork, is to cook it thoroughly.”

Foodborne route of infection
Study findings suggest the epidemiology of hepatitis E in Singapore has shifted, from mainly a disease imported from the Indian subcontinent, to one that is increasingly prevalent in the resident population.

Genotypes from 143 human samples identified 121 to be genotype 3, 21 to be genotype 1 and one to be genotype 4. Further phylogenetic analyses suggested genotype 3a to be the cause of indigenous infections in residents, which showed genetic similarity to the genotype 3a strains detected in pig livers.

“This link between the strains in the majority of human samples and those in pig livers consumed by the public suggests a possible foodborne route of HEV infection in Singapore,” according to researchers.

Hepatitis E is a viral liver disease which may spread from animals to humans through consumption of undercooked or raw pig and game meat, processed pork and shellfish. It is also spread through contact with the feces or vomit of an infected person.

Most people do not require treatment as infections will clear naturally. Pregnant women and older people, those with weakened immune systems, and chronic liver disease can experience more severe infections.

Symptoms of hepatitis E include yellowing of the skin and eyes, known as jaundice, darkening of the urine and pale stools. Tiredness, fever, nausea, vomiting and abdominal pain may also occur.

Illness usually resolves within one to four weeks. The average period of time you can have the infection before developing symptoms is 40 days, with a range of 15 to 60 days.

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