Key Points

Four patients developed sepsis, but none required intensive care, according to the Stockholm regional health authority. Reported symptoms include high fever, diarrhea and vomiting.

Officials said about 400 guests who dined at the restaurant between September 23 and 27 had been contacted for monitoring, while at least 80 suspected food poisoning complaints have been filed.

Infectious disease specialist Viktor Dahl said the number of cases is "unusually high," and the incubation period shorter than normal.

Minister for Social Affairs and Public Health Jakob Forssmed said the government had been briefed and that "extensive work is being carried out across the country to track and assist patients."

The restaurant, now temporarily closed, plans to reopen on October 7, Xinhua news agency reported.

According to the World Health Organization, Foodborne listeriosis is one of the most serious and severe foodborne diseases. It is caused by the bacteria Listeria monocytogenes. It is a relatively rare disease with 0.1 to 10 cases per 1 million people per year depending on the countries and regions of the world. Although the number of cases of listeriosis is small, the high rate of death associated with this infection makes it a significant public health concern.

Unlike many other common foodborne diseases causing bacteria, L. monocytogenescan survive and multiply at low temperatures usually found in refrigerators. Eating contaminated food with high numbers of L. monocytogenes is the main route of infection. Infection can also be transmitted between humans, notably from pregnant women to unborn babies.

The initial diagnosis of listeriosis is made based on clinical symptoms and detection of the bacteria in a smear from blood, cerebrospinal fluid (CSF), meconium of newborns (or the fetus in abortion cases), as well as from faeces, vomitus, foods or animal feed. Various detection methods, including polymerase chain reaction (PCR), are available for diagnosis of listeriosis in humans. During pregnancy, blood and placenta cultures are the most reliable ways to discover if symptoms are due to listeriosis.

- IANS