*Rate per 100,000 population based on the U.S. Census Bureau’s population data as of July 1, 2003
Salmonellosis is a bacterial disease usually transmitted through raw or undercooked foods of animal origin or foods cross-contaminated by animal products or feces. It can also be transmitted person to person. Common reservoirs include poultry; swine; cattle; reptiles, such as turtles, snakes, and lizards; and wild birds, such as ducks and geese.
In 2003, the incidence of salmonellosis in Indiana approximated the incidence in 2002, with 587 cases reported, or 9.5 cases per 100,000 population. Figure 1 shows the number of reported cases for 1999-2003. The incidence was greatest during the summer months (Figure 2). Figure 3 shows age-specific rates were greatest among infants less than 1 year of age (68.0), followed by preschoolers aged 1-4 years (19.4), and children aged 5-9 years (10.7). Females (9.4) were slightly more likely to be reported with salmonellosis than males (9.3), and blacks (7.2) were slightly more likely to be reported than whites (6.6) or other races (1.9).
The incidence rates were highest among the following counties reporting five or more cases:
Tipton (30.2), Knox (20.8), Porter (20.6), Decatur (20.4), and Harrison (19.9). Figure 4 shows Indiana counties reporting five or more cases.
There were two outbreaks of salmonellosis reported in Indiana in 2003. In January, 13 people were reported ill after eating at a funeral dinner or leftovers from the dinner at a private residence in Marion County. Five people tested positive for Salmonella typhimurium, Copenhagen variant. The one food common to all cases reporting a food history was stuffing. All food items were prepared in private homes, so specific information on food preparation was unavailable. Four secondary cases were also identified, all of whom reported having prior contact with a case who consumed food from the funeral dinner.
Another outbreak of salmonellosis was associated with a Hendricks County restaurant in August 2003. Four patrons and one restaurant employee tested positive for Salmonella enteritidis. Bacterial isolates from three of these cases were genetically identical by pulse-field gel electrophoresis testing, strongly implicating a common source. No common food item was identified among all the cases. However, given that the index case was the restaurant employee and that two other employees were later identified as having been ill with compatible symptoms, it is likely that there was a background of illness among restaurant employees. No employee worked while ill; however, since the illnesses were not reported, no follow-up testing or restrictions were implemented.
There are over 3,000 different Salmonella serotypes that differ in somatic and flagellar antigens. The Indiana State Department of Health (ISDH) requests that clinical laboratories submit all positive Salmonella isolates to the ISDH Laboratories for free confirmation and serotyping. During 2003, serotypes were determined for approximately 90 percent of the 587 cases identified. Of the 530 isolates of known serotype, 82 (15%) were enteriditis; 77 (15%) were typhimurium; 43 (8%) were Newport; 42 (8%) were Heidelberg; 40 (8%) were typhimurium, Copenhagen variant; and 246 (46%) were other serotypes.