The number of people sick in a botulism outbreak due to contaminated sardines has grown to 15.

Patients include Americans and Canadians plus people from England, France, Germany, Greece, Ireland and Spain.

At least 10 have been hospitalized and eight admitted to intensive care units. One person has died.

Locally produced and preserved sardines in oil have been confirmed as the vehicle of infection. They were served at the restaurant but not distributed anywher else.

Local media reported that an investigation into the incident has been opened by the Bordeaux public prosecutor’s office.

Botulism type B toxin has been identified in serum samples from some cases, and sardines tested positive for type B Clostridium botulinum.

All patients reported eating at the same outlet in Bordeaux, the Tchin Tchin Wine Bar, before they became sick. The restaurant is close to the Rugby World Cup 2023 fan zone and is in an area popular with tourists.

Investigations by French officials show that up to 25 individuals may have been exposed.

The European Centre for Disease Prevention and Control (ECDC) said the risk of infection for Europeans was considered to be low but more related cases could occur in the coming days.

National authorities on alert

The Public Health Agency of Canada (PHAC) reported three cases are residents of the country.

PHAC said there may be additional cases identified among Canadians in France who ate at the restaurant since symptoms of botulism can take several days to appear.

The agency added it was in contact with federal, provincial, territorial and international partners, such as Santé Publique France, to monitor and address the outbreak.

The Health Service Executive (HSE) in Ireland said a “small number” of Irish citizens had been affected and were receiving care in France. The agency advised people who ate sardines at the restaurant between Sept. 4 and Sept. 10 to seek urgent medical care if they felt unwell.

Three patients had returned to England to be treated. However, there may be more people now in the UK who ate at the restaurant whom the French authorities have not been able to trace, said the UK Health Security Agency (UKHSA).

Botulinum poisoning is a rare but life-threatening condition, caused by toxins produced by Clostridium botulinum bacteria. In foodborne botulism, symptoms generally begin 18 to 36 hours after eating contaminated food. However, they can occur as soon as six hours or up to 10 days later. Symptoms may include double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing or breathing, paralysis, a thick-feeling tongue, dry mouth, and muscle weakness.