Raw Turkey Harbors Harmful Bacteria : Food Safety: A new study claims 32.2% of randomly selected uncooked turkey parts contain the <i> Listeria </i> bacteria. Industry officials dispute the findings.


The potentially deadly Listeria bacteria was found in 32.2% of the uncooked turkey parts randomly selected from supermarket shelves and analyzed for the contaminant by University of California, Davis researchers, according to a recent report.

“The study demonstrated the high prevalence of Listeria and specifically Listeria monocytogenes in (raw) turkey products,” the article, in the Journal of Food Protection, stated. “Turkey meat is . . . a major food source of L. monocytogenes.

In 1985, L. monocytogenes was identified as the pathogen present in the Mexican-style soft cheese, sold under the brand name Jalisco, that caused more than 142 illnesses in Los Angeles County. The outbreak resulted in 47 deaths, mostly stillborn infants.

The UC Davis study is the first to explore the presence of this particular organism in raw turkey meat, according to the journal report.


Poultry industry officials said that the UC Davis figures were inflated, if not outright wrong.

“That sounds phenomenally high to me. I’d be surprised if that figure was true,” said Stuart Proctor, executive vice president of the National Turkey Federation in Reston, Va. Proctor insisted, in any event, that cooking turkey to well doneness, or 185 degrees Fahrenheit, would kill any Listeria present and eliminate the health threat.

Even so, a top U.S. Department of Agriculture official called the UC Davis report a high-quality effort and said the lead researcher, Constantin A. Genigeorgis, is among the best in his field.

Genigeorgis and his colleagues conducted the study in the Department of Epidemiology at the UC Davis School of Veterinary Medicine.

Their findings follow disclosure, earlier this year, of a federal study that indicated Salmonella contamination of chicken may be as high as 60%. The UC Davis study seems findings seem to lend further support to consumer groups’ claims that sanitation is declining in the nation’s poultry processing plants.

“It is a fact of life: we have harmful pathogens in raw poultry,” Genigeorgis said. “A Listeria- positive rate of 32.2% is pretty high. . . . It’s significant.”

Marketing raw turkey or other uncooked meats containing Listeria is not illegal because it is assumed that any bacteria present will be destroyed in the cooking process. However, the federal government has established a zero-tolerance for Listeria in any cooked or ready-to-eat meats such as deli items.

Lester Crawford, administrator of the USDA’s Food Safety and Inspection Service, said that Listeria is ubiquitous, or found throughout the environment. The bacteria is even present at similar levels in some types of fresh produce, he said.

Crawford acknowledged that this particular pathogen necessitates extra caution on the part of manufacturers, retailers and consumers.


Listeria is one of the most troubling organisms to deal with in the food safety realm because it can (survive and breed) in refrigeration,” he said.

The UC Davis study’s initial phase involved testing 225 samples of turkey gathered during three different trips to a slaughterhouse. Twelve, or 5.3%, tested positive for Listeria. Following the slaughterhouse visits, researchers collected 180 turkey part samples--wings, drumsticks and tails--from three supermarkets in the Davis area. Of these, 58 or 32.2% showed signs of Listeria. (Sample collection locations were not named.)

The disparity between the low contamination rates found at the plant and the higher retail levels is an area that needs further study, the researchers stated. However, while conducting the slaughterhouse sampling program Genigeorgis also ran Listeria tests on meat handlers’ hands and gloves. He found 30% positive for Listeria. Thus, employee handling was implicated as a likely source of contamination.

“The current technology for slaughtering birds is not sufficient,” said Genigeorgis. “People are handling so many carcasses (in these plants) that if just one person’s hands get contaminated then it can cause 300, or more, birds to be infected throughout the day.”

The USDA’s Crawford said that the discovery of Listeria on workers’ gloves was troubling.

“It means that the organism is colonizing the (entire) plant. . . . It grows on cold floors and in wet climates. Plant sanitation efforts need to be especially careful,” Crawford said.

An estimated 1,700 people become infected with Listeriosis annually in the United States. However, the actual number of illnesses is vastly under-reported as is the case with virtually every food-borne illness, according to health officials. Even though the number of diagnosed infections is small, Listeriosis has a high fatality rate of between 35% and 40%, according to various estimates.

There is no scientific consensus on how many Listeria cells must be present in food in order to cause illness. Genigeorgis said estimates have varied between 100 and 1,500 organisms. The UC Davis study was not able to determine how many cells were present on those turkeys testing positive for Listeria and the number could have been as low as one organism .

Proctor, with the National Turkey Federation, said that if the UC Davis contamination figures were correct then many more cases of Listeriosis would be reported in this country.

While an otherwise healthy person may not fall ill after ingestion of Listeria- contaminated meat or other foods, there are several groups at severe risk for infection. These include infants, pregnant women, the elderly and those with compromised immune systems, such as cancer or AIDS patients.


“Only 1,700 cases a year means your chances of getting sick are a remote possibility even considering how prevalent Listeria is in the food supply,” said Genigeorgis. “But for those segments of the population where their immune system is (compromised) then that is a totally different story.”

There are several strains of Listeria in the environment, some of which are more invasive than others. Since the Jalisco Mexican-style soft cheese epidemic in Los Angeles, monitoring for the bacteria has been a priority among state and federal regulators.

In the first seven months of 1990 alone, about 50,000 pounds of turkey hot dogs contaminated with L. monocytogenes were recalled by the U.S. Department of Agriculture. Two manufacturers--one Canadian and one American--were implicated. Hot dogs are, by law, required to be fully cooked when shipped from the manufacturer. The presence in ready-to-eat meat of a pathogen, such as L. monocytogenes , is worrisome.

In fact, the Genigeorgis study specifically discussed the problems inherent with the manufacture of turkey hot dogs and warned against eating the popular item undercooked.

Industry representative Proctor said the USDA recall of 50,000 pounds of turkey hot dogs is a very small percent of those manufactured and consumed in this country. He added that the fact the federal government was able to identify L. monocytogenes, and pull the product off the market, shows that the “system is working well.”

An estimated 254 million turkeys were raised in the United States in 1989 and about 42% of that total was further processed into such deli items as hot dogs and turkey ham.

According to the USDA, consumers can protect themselves from suspected Listeria contamination in raw turkey by cooking the meat to an internal temperature of 185 degrees. Keep the uncooked meat refrigerated in a separate wrapping, container or plate away from all other foods to be eaten raw such as fruit. Wash refrigerators according to manufacturers instructions. And avoid using wooden cutting boards to cut raw meat.