Food Poisoning Lawyer & Attorney : Marler Clark : Food Poison Blog

The outbreak investigation into the Listeria outbreak traced to the consumption of Whittier Farms milk products revealed contamination in several areas of the milk plant, according to reports from the Boston Herald and the Metro West Daily News. 

The Massachusetts Department of Public Health announced today:

More than 100 environmental and milk samples were taken from the processing plant as part of the investigation. A total of twelve milk samples and four environmental samples tested positive for varying strains of Listeria contamination (see summary below).

The findings do not pinpoint where the contamination of the milk occurred, but they do suggest that Listeria bacteria colonized somewhere in the processing plant and that the bacteria entered the milk products at some point during the production process. Records indicate that the plant’s equipment met federal standards for time, temperature and flow for effective pasteurization, however, pasteurization at the processing plant will be further examined.

The presence of Listeria in the physical plant of the facility is consistent with contamination occurring during post-pasteurizing processing and bottling. One theory under consideration by health officials is that cleaning activities at the plant may have unintentionally caused contamination of the processing equipment allowing bacteria to enter the finished milk products. Three of the four positive environmental tests for Listeria were collected from sections of the plant that are considered part of the post-pasteurization areas of the facility.

Listeria is the common name for the pathogenic or disease-causing bacterium known as Listeria monocytogenes. It is a foodborne illness that when ingested causes an infection known as listeriosis (Cossart & Bierne, 2001). Approximately 2,500 illnesses and 500 deaths are attributed to listeriosis in the United States annually (CDC, 2005).

Listeria is ubiquitous in the environment, and can be isolated from wild and domestic animals, birds, insects, soil, wastewater, and vegetation. The bacterium easily comes into contact with farm animals as it has been found to be present in grazing areas, stale water, and poorly prepared animal feed. In addition to being present in the environment, Listeria can live in the intestines of humans, animals and birds for long periods of time without causing infection. Because Listeria is present in nearly every environment - including in some food processing facilities - numerous opportunities for contamination exist during the food production process (Cossart & Bierne, 2001).

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The Bellingham Herald reported today on a Campylobacter jejuni outbreak that has been traced to the consumption of raw milk purchased from a Whatcom County, Washington, dairy. 

In December, the Whatcom County Health Department issued a warning to consumers that Campylobacter had been isolated from a sample of milk produced at the Pleasant Valley Dairy in Ferndale.  The Seattle Post-Intelligencer reported:

The bacteria were found in a routine testing sample taken Dec. 11, the department said.

Local health departments are reviewing Campylobacter illness reports that may be related to the milk, the news release said. Symptoms of the illness usually occur two to five days after ingestion and generally last for seven to 10 days.

The milk was sold in half-gallon plastic containers at the Pleasant Valley farm store and at Barganica, Community Food Co-op and Terra Organica in Bellingham; Skagit Valley Co-op in Mount Vernon; Arlington Health, Petosa's, Manna Mills, Tru Health and Bob's Corn Patch in Snohomish County; and Spuds in Seattle, the news release said.

Now, health officials are saying that at least five people became ill with Campylobacteriosis, the illness caused by the ingestion of Campylobacter bacteria, after drinking raw milk produced by the Pleasant Valley Dairy.  According to the story in the Herald:

Four Whatcom County residents and one Skagit County resident tested positive for the same campylobacter jejuni strain that was found in a routine sample of raw milk from Pleasant Valley Dairy. The dairy pulled that batch of milk from the shelves and has resumed its distribution of raw milk.

The dairy has changed its testing procedures to reduce the risk of releasing contaminated milk, the health department said.

Outbreaks traced to the consumption of raw milk are not all that uncommon.  The International Food Safety Network has posted a list of outbreaks on its website.

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Public health officials in Massachusetts have confirmed that a listeriosis outbreak was caused by the consumption of milk purchased from Whittier Farms.  They used Pulsed Field Gel Electrophoresis (PFGE) to obtain the "genetic fingerprint" of the strain of Listeria that was isolated from case-patients and milk provided by the dairy for testing. 

PFGE is a technique used to separate the DNA of a bacterial isolate into its component parts. It operates by causing alternating electric fields to run the bacteria's DNA through a flat gel matrix of agarose, a polysaccharide obtained from agar. The pattern of bands of the DNA fragments — or “fingerprints” — in the gel after exposure to the electrical current is unique for each strain and sub-type of bacteria. By performing this procedure, scientists can identify hundreds of strains of Listeria, E. coli O157:H7, and and other pathogenic bacteria.

PFGE patterns of bacteria isolated from products can be compared and matched to PFGE patterns of bacteria isolated from people suffering illness after consuming contaminated products. When PFGE patterns of bacteria isolated from foods and human samples match, they, along with solid epidemiological work, provide proof that the contaminated product was the source of a person's illness.

The Boston Globe reported on the outbreak investigation today:

"The pattern is very unique," said Dr. Alfred DeMaria, the state's director of communicable disease control. "It means there's an outbreak here. There's no question there's an outbreak. And it implies that the dairy is the common source."

It is exceedingly rare, disease investigators said, to discover that cases of listeria are caused by germs with identical genetic profiles. Instead, each infection tends to be the result of a slightly different form of the bacterium.

In 19 other cases in 2007 in Massachusetts, each infection was caused by a germ with a distinctive fingerprint. Similarly, there were no genetic matches among 99 listeriosis cases in the previous five years.

That, specialists said, is why it was so telling that the samples from the dairy, the patient's refrigerator, and the four patients all matched.

According to the article, the investigation is now focusing on the packaging process as the potential source of contamination. 

More information on the outbreak investigation is available on the MDH website. 

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The Milford Daily News reported that two people died after drinking milk produced by Whittier Farms in Shrewsbury, Massachusetts.  According to the story, the Massachusetts Department of Public Health issued a warning to consumers not to drink milk produced by the dairy because it might be contaminated with Listeria monocytogenes. 

Whittier Farms distributes most of its milk to homes in the greater Worcester/Shrewsbury area under the brands Whittier, Schultz, Balance Rock, Spring Brook, and Maple. The dairy has ceased production until health officials are able to determine where the contamination occurred.

According to the Milford Daily News:

Four cases of listeriosis infection have been identified by DPH, according to a statement released by the state department late this afternoon. The cases occurred in June, October and two in November. The four cases involved three elderly residents and a pregnant woman from Worcester county. Two of the people have died. They have not been identified.

DNA fingerprinting conducted by the State Laboratory Institute showed that the bacteria causing these infections came from a common source. Samples collected showed product contamination.

Pregnant women are about 20 times more likely than other healthy adults to get listeriosis. About one-third of listeriosis cases happen during pregnancy. The incidence of listeriosis in the newborn is 8.6 per 100,000 live births. There is no routine screening test for susceptibility to listeriosis during pregnancy, as there is for rubella and some other congenital infections. Newborns, rather than the pregnant women themselves, suffer the serious effects of infection in pregnancy. Persons with weakened immune systems due to treatment, particularly transplant recipients10 and persons on treatment for lymphoma, but also other cancer victims, are at significantly increased risk for Listeria infection.

• Persons with AIDS suffer listeriosis 65-145 times more frequently than the general population.
• Persons who take glucocorticosteroid medications (also called cortisone) are also at increased risk. The most common medication prescribed in this class is prednisone. The threshold above which prednisone begins to have a significant effect on the immune system is 20 mg per day for 5 days.
• The elderly and certain debilitated patients (such as those on dialysis or alcoholics) are at minor increased risk for listeriosis.

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This week's Morbidity and Mortality Weekly Report (MMWR), a publication from the Centers for Disease Control and Prevention, contains an outbreak report on a Salmonella Typhimurium outbreak associated with the consumption of raw milk and cheese produced at a Pennsylvania dairy beginning in February, 2007. 

According to the report, several people who consumed raw unpasteurized dairy products from the dairy became ill with Salmonellosis and the strain of Salmonella isolated from ill people's stool was indistinguishable from that isolated from a bulk dairy tank at the dairy.  In all, 29 cases of Salmonella were identified as part of the outbreak.

The Pennsylvania Department of Health findings regarding the Salmonella outbreak are summarized in the report:

A total of 29 cases were identified, with illness onset occurring in three temporal clusters during February 3--July 14, 2007 (Figure). The first cluster consisted of 15 cases with onsets of illness from February 3 to March 5. Raw-milk samples were collected February 20 from a dairy A bulk milk tank and February 28 from the home of an ill person. Both sets of samples yielded the outbreak strain of S. Typhimurium. On March 2, PDA ordered dairy A to stop raw-milk sales and advised the public not to consume raw-milk products from dairy A.

On March 19, PDA allowed dairy A to resume sales of raw milk after PDA conducted inspections and recorded two consecutive negative cultures from milk-tank samples. However, a second cluster of three cases was detected when the outbreak strain of S. Typhimurium was identified in another patient, whose diarrheal illness began on March 21 and who had consumed raw milk from dairy A after sales resumed. The two additional cases were identified in persons with onsets of illness on March 19 and March 22. The first of these occurred in one of six ill persons who primarily spoke Spanish and who told investigators they had not consumed raw milk. However, when reinterviewed in early April, three of these six persons reported consuming queso fresco (a type of soft cheese) they bought at a grocery store serving the local Hispanic community. PDA learned that the queso fresco had been made by an unlicensed producer who purchased approximately 20 gallons of raw milk weekly from dairy A. Sale of raw-milk cheeses aged <60 days is illegal in Pennsylvania. Subsequently, in April, PDA inspectors seized 18 unlabeled retail containers of queso fresco from the grocery store. The cheese tested positive for alkaline phosphatase, indicating the cheese was produced from unpasteurized milk (2). Bacterial cultures were negative for pathogens.

On March 27, PDA again ordered dairy A to halt raw-milk sales and suspended its raw-milk permit. No additional cases were noted until June--July 2007, when a third cluster of 11 PFGE-matched S. Typhimurium cases was detected through routine electronic laboratory reporting. Of these, 10 occurred among residents of three counties near dairy A. On July 19, PDA confirmed that dairy A had been distributing raw milk to the public despite its suspended permit; the date when illegal milk distribution began could not be determined. The outbreak strain of S. Typhimurium was isolated from dairy A raw milk collected from a bulk milk tank on July 19 and from the home of an ill person on July 20. PDA ordered dairy A to halt distribution of raw milk on July 20 and subsequently revoked the raw-milk permit for this dairy.

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