Food Protection Trends - April 2009 - 216

unpasteurized milk consumption (19). These students showed high levels of C. jejuni-specific antibodies compared to the unexposed population (19). Of the 25 students who consumed the raw milk for the first time, 22 were infected, whereas neither of the two students who did not consume the raw milk were infected (19). Although C. jejuni is more commonly found in unpasteurized cows’ milk, goats’ milk has also been documented as a source of infection; in Washington State, it was identified as the source of C. jejuni enteritis among six patients (52). Although the organism was not recovered from the milk, it was isolated from the intestinal tract of three goats from one dairy, and other C. jejuni isolates were obtained from goats at another dairy (52). An outbreak of C. jejuni enteritis in Utah occurred at a high school athleticteam dinner at which unpasteurized milk was served. In this case-control study, all cases (those experiencing illness) reported diarrhea, abdominal pains, nausea, vomiting, body aches, chills, and headaches four days after the team dinner; in contrast, none of the controls (those not suffering from any illness) had consumed the milk served at the team dinner. The consumption of unpasteurized milk was significantly associated with C. jejuni enteritis (OR = 30.0, 95% CI 1.58 – 153, P = .0072) (76). consumption dose-response trend was highly statistically significant (P = 0.008), with disease rates of 3.6% for 0–0.9 cups of milk, 6.7% for 1–1.9 cups, 14.3% for 2–2.9 cups, and 37.5% for > 3 cups (35). Shiga toxin-producing strains of E. coli are also known to cause hemolytic uremic syndrome (HUS), a potentially fatal disease occurring mostly in children and infants (94). A majority of cases experience acute renal failure (97%) and gastroenteritis (83%). In 1997, four cases of HUS were reported in the Czech Republic in children who had consumed raw goat’s milk. The levels of anti-O157 LPS antibodies (which can be associated with E. coli infection) were found to be significantly higher among those who regularly consumed a particular farm’s goat milk (33%; 5 of 15 regular drinkers) compared to a control population (0%; 0 of 45) (P = 0.0005) (18). In Austria, enterohemorrhagic E. coli O26:H infection was also linked to the consumption of raw cows’ and goats’ milk in two children, both less than three years of age (3). Both children had severe bloody diarrhea and one child developed HUS. brucellosis infection occurs. Approximately 10% of all cases in the U.S. are attributed to consumption of unpasteurized milk and milk products (105). Several studies have suggested that unpasteurized milk has been a source of C. burnetii, the causative agent of Q fever (38, 41, 93). Hatchette and colleagues noted that 37% of those affected by a goat-associated Q fever outbreak in Newfoundland had antibody titers to phase II C. burnetii antigen > 1:64, suggesting that infection with this organism had occurred (53). Consumption of unpasteurized milk contaminated with L. monocytogenes in pregnant women is also known to cause miscarriage, fetal death, or illness or death of a newborn (28). Infections caused by Toxoplasma gondii and Corynebacterium pseudotuberculosis have also occurred in persons who have consumed unpasteurized milk (77, 80). THE EVIDENCE Cow-shares Cow-share programs involve a farm cooperative in which members lease cows from a dairy farm and then sell shares in the herd to the cooperative members. Typically, a member pays an annual fee and, in return, is given purchasing rights to the herd’s milk. In turn, the dairy farmer uses the annual fees as boarding fees for the cows. Outbreaks of foodborne illness have been linked to raw milk purchased through such cow-sharing programs (31). In 2005, eighteen cases of E. coli O157:H7 were associated with raw milk consumption among shareholders of a cow-share program in Oregon (33). Five patients, all younger than fourteen years of age, required hospitalization, and four developed hemolytic uremic syndrome (33). Other diseases In 1996 and 1998, two separate incidents in Massachusetts involving the consumption of unpasteurized milk from rabid cows led to mass rabies postexposure prophylaxis (PEP) of 80 people (29). The median cost of this treatment in Massachusetts was reported as $2,376 per person during the period 1991–1995 (65). In 2005, the milk of a rabid cow in Oklahoma was mixed with that of approximately 70 other cows, and as a result, hundreds of consumers were potentially exposed (34). Sixty-two consumers received PEP at an estimated cost of $186,000 No humans were reported to have contracted rabies through ingestion of unpasteurized milk from any of the rabid cows. Although rabies infection through ingestion of unpasteurized milk has not been described in the literature, it is theoretically possible; rabies transmission through ingestion of milk from rabid animals has been reported (2). Pasteurization, however, inactivates the rabies virus (89). Other organisms present in raw milk have also been implicated in human disease. Globally, milk and milk products are the primary means by which human Escherichia coli E. coli and Shiga toxin-producing E. coli have been found in 0.87% to 10% of bulk tank samples of unpasteurized milk in Minnesota, Ontario, Pennsylvania, South Dakota and Wisconsin (59, 74, 88). Sixteen cases of E. coli infection caused by raw milk consumption were reported in Oregon, where four of the 132 animals of the herd tested positive for the organism (63). The infection led to gastrointestinal symptoms in those affected. Interestingly, despite new labeling requirements, increased monitoring of dairy sales from the implicated dairy farm, and public health efforts to warn the public of hazards associated with raw milk consumption, retail sales continued and illnesses ensued (63). In the state of Washington in 2005, an outbreak of E. coli resulted in illness among eighteen people, most of whom were children. The relative risk for illness increased steadily with the average number of cups of raw milk consumed daily. The average daily pasteurized milk outbreaks The rare outbreaks attributed to pasteurized milk can generally be traced to post-pasteurization hygiene, namely inadequate pasteurization and/or contamination after pasteurization (47). In 1983, an outbreak caused by L. monocytogenes in Massaschusetts affected 42 immunocompromised adults and seven fetuses or infants (47). Fourteen of these patients died because of disease-related meningitis, septicemia, or spontaneous abortion (47). In this outbreak, two case-control studies (one matched by neighborhood, one matched by under- 216 FOOD PROTECTION TRENDS | APRIL 2009

Food Protection Trends - April 2009

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