The health ministry said Dec. 14 that potentially deadly E. coli bacteria has been detected in cow livers for the first time, raising the likelihood of a government ban on raw liver, a popular dish in Japan.
Officials will report the results on Dec. 20 to a ministry council that could recommend an immediate ban on the serving of uncooked liver.
A government ban would sanction punishment of violators under the Food Sanitation Law.
Campylobacter bacteria, which can cause food poisoning, was already known to exist in cow livers, but the discovery of enterohemorrhagic E. coli bacilli, which causes bleeding in the intestines and includes the deadly O-157 strain, is a far more serious development.
The Ministry of Health, Labor and Welfare asked the meat inspection offices of 16 local governments, including the Tokyo metropolitan government and the Osaka city government, to check cattle livers this year.
Local officials checked the livers of 150 cows after butchering in August and September and the results were tallied by Kunihiro Shinagawa, professor emeritus of veterinary medicine at Iwate University.
The O-157 strain of E. coli bacteria was found in the livers of two cows and gene tests also found other enterohemorrhagic E. coli strains in several other livers. The ministry suspects that the total number of heads of cattle whose livers are confirmed to have contained E. coli bacteria will reach about 10, or about one in 15 of the animals checked.
The tests were conducted by extracting 25 grams from each liver. Cow livers weigh several kilograms, so, even if no bacteria were found in a sample, there is still a possibility of infection in the remaining portion.
It was found that O-157 strain proliferates in bile produced in the livers. The ministry suspects that O-157 present in intestinal tracts can move to the animal's bladder, which stores the bile, and then enters the liver.
Previous reports of raw cattle liver causing enterohemorrhagic E. coli food poisoning had been explained as cases of cross contamination. The theory was that bacteria existing in the intestines had attached to the surfaces of livers when meat was being processed. The latest results blow a hole in that theory, suggesting that livers themselves can be infected.
The current expert advice is that liver should be cooked for more than a minute at 75 degrees to avoid the risk of poisoning.
The health ministry is asking local governments to instruct restaurants not to offer raw livers to their customers until the final results of the survey are announced. However, those instructions are not legally binding and some restaurants are still offering raw livers to their customers.
Between 1998 and 2010, the ministry received 116 reports of food poisoning from raw livers.
In response to a series of food poisoning cases that took place in a barbecue restaurant chain in April this year, the health ministry reviewed standards on the use of raw beef served for "yukhoe" and other dishes. During that review, the ministry also examined raw livers.
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