Over 90% of cases of a common form of food poisoning seen this year were due to people eating undercooked chicken liver pate, often at weddings, infection experts have said.The Health Protection Agency (HPA) analysed 18 outbreaks of Campylobacter in 2011 across England.In all, 443 people became unwell and one had to be hospitalised.The Food Standards Agency (FSA) has reminded caterers to cook poultry livers to prevent infection.Campylobacter is the most common cause of bacterial food poisoning in Britain - there were estimated to have been more than 600,000 cases in 2010 in England and Wales.Symptoms include diarrhoea, stomach pains and cramps, fever, and generally feeling unwell. Most people are only ill for a few days.In 2008 there were just three outbreaks linked to undercooked chicken liver pate, but that rose to nine in 2009 and 14 in 2010.Poultry livers carry a particularly high risk of Campylobacter as the bacteria can be present throughout the liver, not just the surface as is the case for other poultry meat, and may remain a source of infection if they are not cooked sufficiently.Of the 18 outbreaks, 14 occurred in catering venues, and 13 of these were linked to chicken or duck liver pate.Seven were linked to wedding receptions at hotels, banqueting venues or public houses and six were associated with catering at other functions such as hotels, clubs and restaurants.The HPA found that livers used to make the parfait or pate were undercooked allowing the liver to remain pink in the centre.It said caterers can reduce the risk of their people becoming infected by ensuring that Campylobacter is killed through proper cooking and by avoiding cross-contamination to other foods.Dr Christine Little, an expert in gastrointestinal infections at the HPA, said: \"The increase in outbreaks which are due to the consumption of chicken liver pate has been steadily increasing over the last few years.\"Not only is this dish popular in food recipe magazines, it is being served in a variety of different catering venues.\"Illness occurs because the livers are only cooked until they are pink, and inadequate cooking will not be sufficient to kill the bacteria.\"Both the public and the catering industry need to be aware that undercooking this product can result in food poisoning.\"She said anyone planning a wedding, or other special event, should be aware of the risks if they were having chicken liver pate to prevent people becoming unwell.The FSA issued updated advice to caterers on the safe handling and cooking of livers twice in 2010, but Campylobacter outbreaks associated with the consumption of chicken liver pate have continued to occur.Bob Martin, head of foodborne disease strategy at the FSA, said: \"Unfortunately, levels of Campylobacter in most raw chicken are high, so it\'s really important that chefs cook livers thoroughly to kill any bacteria, even if recipes call for them to be seared and left pink in the middle.\"The only way of ensuring the pate or parfait will be safe to serve to your guests or customers is by cooking the livers the whole way through.\"Caterers should also follow good general hygiene practices when cooking and handling poultry livers, to avoid cross contamination with Campylobacter.\"