It is very difficult to prove you have got food poisoning from a restaurant, writes Rosita Boland

Paying to be poisoned. You could argue that's what happens when you pay good money to go out and eat, whether at a modest fast-food joint or a reputable restaurant, only to end up some hours later with your head down the toilet.

Until recently, I had managed to escape food poisoning. This happy record included long stints of travelling in Asia, where I ate virtually everything, even food from street stalls, with zero ill-effects. When it came to the inevitable exchange of horror stories of experiences, none of my fellow travellers believed me when I confessed I had no stories to tell. I appeared to have an almost embarrassingly cast-iron Celtic dustbin constitution.

My record ended when I was visiting friends in Cork and we went out to eat together at an established restaurant that had been well-reviewed. One of my friends had lamb shank. The other had fillet steak. I - oh, unlucky choice! - had venison casserole.

It was a large portion, so large that I left almost a third of it. Most of this was polished off by one of my friends after he'd finished his steak. The marvellous weekend ended for me at 4am, when I woke up feeling ghastly beyond description and proceeded to become a paid-up member of the food-poisoning club. My luckless friend who had eaten part of the venison was also ill, but since he had eaten less than me, was not as ill. My other friend, who didn't eat any of it, was fine.

I am convinced we both got food poisoning from eating that venison. But I'll never be able to prove it.

"We don't class anything as solely being caused by food poisoning any more, as people used to dump everything into that category," explains Dr Paul McKeown, a specialist in public health medicine at the Health Protection Surveillance Centre. "There are a wide range of different bugs that cause vomiting and diarrhoea. It's a very complex issue."

McKeown explains that since the vast majority of people who temporarily become sick in this way simply let it pass over, and do not see a doctor, it is impossible to do samples to see the source of the illness.

There are, unfortunately, many ways in which the food that arrives on your plate can become contaminated. The food itself does not need to be off to make you sick: if it has been prepared or served up unhygienically, the bacteria count it picked up along the way can be enough to make you ill. This is why, quite often, there can be isolated incidents of "food-poisoning" at restaurants: for example, several people may have eaten the same dish, but only a few will be ill, were they unlucky enough to get the plate handled by the bacteria-carrying waiter who had not washed his hands.

Although restaurants can, and do, have closure orders issued on them by the Food Safety Authority of Ireland (FSAI), as an individual, to prove an incident of food poisoning against a restaurant is virtually impossible due to the complexities of scientifically tracing back to the source of the bacteria.

Closure orders are issued by the FSAI, "if in the opinion of the authorised officer, there is or there is likely to be a grave and immediate danger to public health at or in the food premises". Last year, the FSAI issued closure orders on 27 food outlets. In 2004, there were 42.

Whatever about being an ordinary diner, what do you do if you are a food critic and become ill in the line of duty? Irish Times food critic, Tom Doorley, estimates he has had food poisoning five times over 11 years. "I still remember the quality of the nausea," he says. Because alleging that he had received food poisoning in a restaurant would almost certainly result in legal action, he simply didn't publish reviews of the restaurants.

"Reporting the place to the FSAI is the responsible thing to do. They can investigate further - food storage, temperatures food is held at, hygiene, all those things. The old problem is law. Unless you can prove it in a court of law, you can't do anything publicly about it."

What does the Restaurants Association of Ireland recommend that their members do should someone believe that they have got food poisoning on their premises?

"We don't issue any guidelines in that area," says the association's chief executive, Henry O'Neill. "Food poisoning is a very difficult thing to diagnose. It could be a viral thing, for instance. There are many ways you can get sick. But I would imagine that most good restaurants would contact their local health authority immediately."

"There's a great tendency to look for someone to blame when you get sick after eating out," observes food writer Hugo Arnold. "I think people are very very quick to blame the restaurant first."

What does he think is more damaging to a restaurant: a bad review (that doesn't mention food poisoning) or word of mouth from customers who think they got food poisoning at a certain restaurant?

"Any review is a good review. It's publicity," Arnold says. The opposite is true of bad word of mouth. "Five people telling five more people they think they got food poisoning there is the worst scenario of all. The word keeps spreading, whether it's justified or not."

As for my own experience, the restaurant in Cork said it had received no other complaints about the venison dish that night. I'll never know whether or not it was the cause of my illness but, certainly I won't be eating there again, and I won't be recommending it to anyone else either.

The FSAI advice line on 1890-336677 provides information and advice on food safety issues. It is staffed by trained advisers and food scientists, Mon-Fri, 9am to 5pm