Salmonellosis, 2004

During 2004, 643 culture-confirmed cases of Salmonella infection (13.1 per 100,000 population) were reported. This represents a 12% increase from the 576 cases reported in 2003 and a 4% increase from the median annual number of cases reported from 1996 to 2003 (median, 619 cases; range, 576 to 693) (Figure 1). Four serotypes, S. Typhimurium (164 cases), S. Enteritidis (111 cases), S. Newport (65 cases), and S. Heidelberg (33 cases) accounted for 58% of cases reported in 2004. There were seven cases of S. Typhi infection. Only one of the S. Typhi cases traveled internationally, two lived in the same household, and one was a group-home resident where an asymptomatic carrier was identified. Four percent of salmonellosis case-patients were less than 1 year of age, and 25% were 12 years of age or younger. Twenty-five percent of case-patients were hospitalized for their infection. Of 592 case-patients that were interviewed, 96 (16%) traveled internationally during the week prior to their illness onset.

Three case-patients died. Isolates from these case-patients included one S. Subspecies I isolated from blood, one S. Newport isolated from stool, and one Salmonella group C2 from stool. Two of the cases had serious underlying medical conditions; one had lung, stomach, and prostate cancer, and the other had complications following surgery for a chronic gastroesophageal condition. The third case was an 87-year-old person whose Salmonella infection was listed as the primary cause of death.

Eight outbreaks of salmonellosis were identified in 2004. Four outbreaks involved foodborne transmission. Person-to-person transmission resulted in one outbreak. The remaining three outbreaks involved infected pets.

Three cases of S. Enteritidis with illness onsets in May through July reported eating at the same restaurant before their illness. Several deficiencies in food holding and preparation, including inadequate refrigeration and potential for cross-contamination were found at the restaurant. Two environmental samples (underneath a sandwich cutting board and egg grill) tested positive for S. Enteritidis. An asymptomatic cook also tested positive for S. Enteritidis.

In June, six persons became ill with S. Agona after attending a graduation party. Eighteen additional cases of gastrointestinal illness were identified but were not tested for Salmonella. Samples of the turkey and turkey/soup mixture left over from the event tested positive for S. Agona.

From August through October, three cases of S. Typhimurium who had eaten ground beef purchased at a member-only warehouse were identified. One of the three cases reported tasting the raw ground beef after purchase and before storing it in the freezer. Cases of S. Typhimurium associated with ground beef from the same warehouse chain were identified in at least two other states.

In November, 20 S. Newport cases among employees of a medical clinic were identified. An additional 23 ill persons were identified but not tested. Gravy served at a catered lunch was the implicated vehicle. Undercooked turkey that was being prepared concurrently likely contaminated the gravy. In December, two cases of S. Newport were identified that reported eating at the restaurant that catered the medical clinic lunch. Three asymptomatic restaurant employees tested positive for S. Newport. The cases among restaurant patrons may have resulted from environmental contamination that occurred during the preparation of the turkey for the earlier catered lunch. It is possible that the infected foodworkers played a role in transmission.

A person-to-person outbreak occurred among residents of a nursing home. Two nursing home residents tested positive for S. Newport in August, and an additional resident tested positive in November.

In March, a cluster of four S. Typhimurium cases was identified. Two of the cases lived in a group home, and the other two cases were family members of one of the group home residents. These family members had adopted two puppies from the group home. The two adopted puppies tested positive for S. Typhimurium. Some of these cases likely occurred due to contact with feces of the infected dogs, but person-to-person transmission could have also played a role.

Two S. Javiana cases occurred in a 3-month-old and a 7-month-old infant in July. The family of one of the infants had a dog that was ill with diarrhea earlier in July. A stool specimen from the dog tested positive for S. Javiana. After the dog recovered, the two families and the dog spent time at a cabin. While at the cabin, one of the infants became ill with diarrhea; 2 days later the second infant became ill as well.

One S. Typhimurium case in a 5-year-old child was part of a multi-state outbreak associated with infected pet rodents. Cases in this outbreak were identified in 10 states.

• For up to date information see>> Salmonellosis (Salmonella)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2004