One person has died and at least eight are in intensive care after an outbreak of botulism at a wine bar in Bordeaux in southwestern France.

French health officials say 12 people have been diagnosed with the rare but potentially fatal illness. Most were tourists who ate at the popular Tchin Tchin Wine Bar last week. There were several nationalities among those being treated, including Americans, Canadians, Irish and Germans.

Eight people are still in the hospital in Bordeaux and another was hospitalized in the Paris region. An Irishman who had been in the bar is in intensive care in a hospital in Spain.

Botulism is a serious illness caused by a toxin that attacks the body’s nerves, according to the Centers for Disease Control and Prevention.

Bordeaux is a popular tourism area – and is one of the host cities for the Rugby World Cup 2023 currently underway in France. The city hosted thousands of Irish fans at the weekend who travelled to see Ireland defeat Romania in their opening game on Sept. 9.

It’s understood a large group of Irish fans were at the bar ahead of the game. The Irish Embassy in Paris tweeted a warning to Irish fans who might have been to the wine bar while in Bordeaux.

The health authority believes it has identified the source of the toxin as sardines that the restaurateur had canned himself. Local health officials said there were enough affected sardines to potentially contaminate 25 people.

Officials have called on anyone who ate at the Tchin Tchin Wine Bar in Bordeaux between Sept. 4 and 10 to immediately see a doctor if they have any symptoms. Early symptoms include fatigue, weakness and vertigo, followed by blurred vision, a dry mouth and a difficulty in swallowing or speaking, according to the World Health Organization.

There are usually between 20 and 30 botulism cases per year in France. Antidotes for the toxin are held by the army.

Emergency room doctor Benjamin Clouzeau from the CHU Pellegrin hospital in Bordeaux told French media this outbreak was “exceptional” and very serious. He said it was vital that anyone who had been to the bar and felt any kind of symptoms should seek medical assistance.