October 14, 2015
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Consumption of pork stuffing leads to asymptomatic hepatitis E outbreak

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A recently published investigation has attributed a French outbreak of asymptomatic hepatitis E to the consumption of a piglet prepared with raw pork liver stuffing.

“Results of the epidemiological and veterinary investigations suggest that this outbreak was due to contaminated spit-roasted piglet,” the researchers wrote. “In industrialized countries, acute [hepatitis E virus (HEV)] infections are an emerging concern and clusters of cases, linked to HEV foodborne transmission, remain rare and small. To our knowledge, only four previously published investigations revealed clinical HEV strains homologous to strains recovered from food leftovers.”

In December 2013, three cases of HEV on a coastal island in France were reported to the country’s public health surveillance. The cases were detected in serum samples using reverse transcription-PCR, with all strains belonging to the same sequence subtype. Those infected reported attending a wedding where a spit-roasted piglet stuffed with a raw stuffing — composed of minced liver and heart, vegetables and wheat semolina — was served.

The researchers also interviewed 111 other attendees via telephone to determine demographics, symptoms, associated medical attention and exposures to food and drink that was served. Attendees were encouraged to discuss or receive testing with their general practitioners, creating a cohort of 38 sampled participants with no evidence of past HEV infection. Positive cases were compared with the outbreak strain by phylogenetic analysis, as well as with identified samples from the piglet’s herd and from wastewater collected from plants on the island.

Along with the three confirmed index cases, public health surveillance identified 14 new cases of potential HEV infection. The median age of these patients was 52 years, 82.4% were female, two were hospitalized and all but one were from the island where the incident occurred. Only five of the cases showed symptoms, implying that 70.6% of identified cases were asymptomatic.

Piglet stuffing was consumed by more than half of identified cases, and consumption was independently associated with acute HEV infection (RR = 1.69; 95% CI, 1.04-2.73). All nine samples collected from the farm where the piglet was reared were positive for HEV, and HEV RNA was detected in wastewater samples collected at two treatment stations 6 days after the wedding. Phylogenetic analysis of strains collected from the farm and the wastewater were 100% identical and 99% to 99.6% similar when compared with the three clinical strains recovered from index cases.

“Our investigation attributed the outbreak to the consumption of undercooked stuffing partly made from a piglet’s liver. Our paper illustrates and confirms the need to cook thoroughly pig liver-based food,” the researchers concluded. – by Dave Muoio

Disclosure: The researchers report no relevant financial disclosures.