Norovirus was the cause of more than 120 illnesses in late December 2021 in Slovenia, according to findings of an investigation.
The National Institute of Public Health (NIJZ), the Administration for Food Safety, Veterinary Sector and Plant Protection (UVHVVR) and the National Laboratory of Health, Environment and Food (NLZOH) investigated the outbreak in the town of Ilirska Bistrica.
Officials said based on the clinical symptoms of patients, the duration of disease and results of laboratory tests, the cause of the illnesses was norovirus.
Between Dec. 25 and 30, 2021, an outbreak of an infectious disease was detected in Ilirska Bistrica and 123 people became ill with at least one person being hospitalized.
Most people infected suffered from vomiting and watery diarrhea but some also reported a fever, nausea and abdominal pain.
Spread linked to packaging
Norovirus was isolated as the causative agent in nine fecal samples from infected individuals. Bacillus cereus was also found in one fecal sample.
The investigation showed that the source of infections was not food from a meat shop and it was also not staff, as norovirus was not isolated in employee fecal samples.
It is thought the virus spread to the packaging in which the food was stored after contact with surfaces touched by infected customers. The possibility of previously infected people being responsible was not ruled out by NIJZ.
Officials said one contributing factor was the fact that there were more people in the shop than normal.
Norovirus is a very contagious virus that causes vomiting and diarrhea. People can get it from having direct contact with an infected person; consuming contaminated food or water or touching contaminated surfaces or objects and then putting putting their fingers in their mouths.
A person usually develops symptoms 12 to 48 hours after being exposed and most people with the illness get better within 1 to 3 days. Norovirus can be found in vomit or feces before patients start feeling sick and can stay in feces for two weeks or more after patients feel better.
Initial link to meat
UVHVVR conducted an inspection at the shop linked to the outbreak at the end of December to try and find the cause. It was temporarily closed until the health of employees was assessed.
The initial suspected source was consumption of meat products prepared and sold at the site including steak tartare as sick people all purchased food in the same shop in Ilirska Bistrica.
Officials also did an epidemiological investigation, took swabs to check cleanliness of the implicated equipment and shop, did a medical examination of employees, took samples of suspected meat products from sick people and checked past inspections results.
Thirteen people reported eating steak tartare from the shop and did not become sick. Twelve people said they did not eat any of the suspected foods but fell ill a day or two later. At least some of the illnesses are thought to have been caused by person-to-person transmission.
Microbiological testing of steak tartare found all analyzed parameters were within acceptable limits.
A stricter hygiene plan was proposed at the site involving work surfaces and equipment, which was carried out before the store reopened and no new infections have been reported since.
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