The CDC’s publication, Morbidity and Mortality Weekly Report, contains a report on an outbreak of Salmonella Oranienburg that was determined to have originated from fruit salad served in health care facilities in the Northeastern United States and Canada in 2006. While public health officials were unable to determine which fruit ingredient in the salads was the source of the outbreak, they did note the following:
Fruits such as cantaloupe and honeydew melon previously have been associated with salmonellosis outbreaks in the United States. During 1973–2003, a total of 11 cantaloupe-associated salmonellosis outbreaks were reported to CDC. Reported outbreaks were associated both with whole melons contaminated in growing fields and with precut melons. Cut fruit can be contaminated during processing when rind is removed and fruit is sliced. Furthermore, because the inner flesh of melons contains nutrients that can support microbial growth, improper refrigeration of cut fruit can cause bacteria proliferation.
The public health officials conducting the investigation into the Salmonella outbreak performed a case-control study, interviewing outbreak- and non-outbreak patients and found:
A case was defined as culture-confirmed S. Oranienburg infection with the outbreak strain and illness onset from June 15 to July 31. Forty-one cases of S. Oranienburg with the outbreak strain occurred in 10 U.S. states and one Canadian province: Massachusetts (12), New Hampshire (nine), New York (four), Pennsylvania (three), Vermont (three), Kentucky (two), Maine (two), Maryland (two), Connecticut (one), New Jersey (one), and Ontario, Canada (two). Date of illness onset ranged from June 15 to July 25 (Figure). The median age of patients was 59 years (range: 8 months–96 years); 31% of cases were in persons aged >70 years. Twenty-eight (68%) patients were female. Symptoms reported by patients included diarrhea (74%) (i.e., three or more loose stools in a 24-hour period), abdominal cramps (52%), fever (39%), vomiting (23%), and bloody diarrhea (16%). Seven (17%) patients were hospitalized as a result of their Salmonella infections. No deaths were reported.
Among the 41 cases, 30 (73%) occurred among persons who worked, stayed, or ate in a health-care facility during the 7 days preceding illness onset, including 10 already-hospitalized patients, 10 residents of a long-term–care facility, nine employees of health-care facilities, and one visitor who had eaten in a hospital cafeteria. The interviews with 33 of the 41 patients suggested that illness was associated with eating fruit salad in a health-care facility; 23 (70%) reported eating fresh fruit salad, 19 (83%) of whom had eaten fresh fruit salad in a health-care facility.