Outbreaks of Escherichia coli O157:H7 infection and cryptosporidiosis associated with drinking unpasteurized apple cider - Connecticut and New York, October 1996

Morbidity and Mortality Weekly Report, Jan 10, 1997

In October 1996, unpasteurized apple cider or juice was associated with three outbreaks of gastrointestinal illness. In the Western United States, an outbreak of Escherichia coli O157:H7 infections associated with unpasteurized commercial apple juice caused illness in 66 persons and one death (1). In addition, one outbreak of apple cider-related E. coli O157:H7 infections and another of cider-related Cryptosporidium parvum infections occurred in the Northeast. Apple cider is a traditional beverage produced and consumed in the fall. Cider often is manufactured locally at small cider mills where apples are crushed in presses, and the cider frequently is not pasteurized before sale. This report summarizes the clinical and epidemiologic features of the two apple cider-related outbreaks, which suggest that current practices for producing apple cider may not be adequate to prevent microbial contamination.

Connecticut

On October 11, the Connecticut Department of Public Health (DPH) was notified by staff of the Connecticut site of CDC's Foodborne Diseases Active Surveillance Network of four reported cases of E. coli O157:H7 infection in residents of New Haven County (1995 population: 794,785). An investigation of this cluster was initiated by DPH. A case was defined as onset of diarrhea (i.e., three or more loose-stools per day) during October 1-11 in a Connecticut resident and laboratory-confirmed infection with F. coli 0157:H7. Additional case-finding was conducted by notifying all Connecticut clinical laboratories of a possible outbreak of E. coli O157:H7 infection and requesting that cases be reported immediately to DPH. As a result of active case-funding, DPH initially identified eight cases with onset during October 3-11.

Of the eight case-patients, six were female, and ages of all eight ranged from 2 to 73 years (mean: 25 years). Case-patients resided in six towns within New Haven County. Manifestations included bloody diarrhea and abdominal pain (eight patients), vomiting (five), and fever (four). Duration of illness ranged from 3 to 11 days (median: 7 days). Five patients were hospitalized, including one with hemolytic uremic syndrome (HUS) and one with thrombotic thrombocytopenic purpura.

On October 17, DPH conducted a matched case-control study to determine probable sources for the outbreak. Controls were selected from telephone-exchange lists and were matched to cases by sex, town of residence, and age group. Controls reported no diarrhea during the 20-day period beginning 10 days before illness onset in their matched cases. Case-patients were asked about food consumption during the 7 days preceding illness, and controls were asked about consumption during the same 7 days as their matched cases. Based on interviews with the first eight case-patients and 21 controls, increased risk for illness was associated with drinking fresh apple cider during the 7 days preceding onset of illness (matched odds ratio [OR]=12.0; 95% confidence interval [CI]=1.3-111.3; p [is less than] 0.01). Specifically, illness was-associated with drinking brand A cider (matched OR=undefined; 95% CI=3.5-infinity; p [is less than] 0.01). No other food item (including ground beef, unpasteurized milk, or lettuce) or common event was significantly associated with increased risk for illness. Of the eight patients, seven reported drinking brand A cider during the 7 days preceding illness.

After completion of the case-control study, six additional patients were identified; of these, four had culture-confirmed infection, and two had been hospitalized with HUS but did not have culture-confirmed E. cold 0157:H7 infection. All six had a history of drinking brand A cider. Ten of the 12 outbreak-associated isolates of E. coli O157:H7 were sent to CDC for pulse-field gel electrophoresis typing; all 10 were determined to be closely related.

On October 18, DPH and the Connecticut Department of Consumer Protection (DCP) advised Connecticut residents to discard or boil before drinking all brand A cider purchased since the beginning of the cider season in September. pop coordinated a recall of brand A cider from all retail outlets. Approximately 9000 gallons of the cider had been distributed throughout Connecticut and three neighboring states. pop and the regional office of the Food and Drug Administration (FDA) notified regulatory agency and state health department personnel in the three neighboring states of the recall.

Brand A cider was pressed at a mill in a residential area from apples purchased from multiple sources. Some of the apples used were "drop" apples (i.e., apples picked up from the ground). All apples were brushed and washed in potable municipal water in a flow-through wash system before pressing in a wooden press. Potassium sorbate 0.1% was added as a preservative; the cider was not pasteurized.

New York

During October 10-15, a local hospital laboratory notified the Cortland County Health Department (CCHD) about 10 cases of laboratory-confirmed cryptosporidiosis with recent onset among county residents (1990 population: 48,963). During the same period in 1995, one case of cryptosporidiosis was reported to CCHD. All case-patients had onset of symptoms during September 28-October 10 and reported drinking apple cider produced at a local cider mill (mill A). CCHD, the New York State Department of Health (NYSDOH), and the New York State Department of Agriculture and Markets (NYS A&M) initiated an investigation of this cluster.