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From 1996 to 2004, the incidence of Salmonella Javiana infections increased in FoodNet, the U.S. national active foodborne disease surveillance programme. Contact with amphibians and consumption of tomatoes have been associated with outbreaks of S. Javiana infection. To generate and test hypotheses about risk factors associated with sporadic S. Javiana infections, we interviewed patients with laboratory-confirmed S. Javiana infection identified in Georgia and Tennessee during August-October 2004. We collected data on food and water consumption, animal contact, and environmental exposure from cases. Responses were compared with population-based survey exposure data. Seventy-two of 117 identified S. Javiana case-patients were interviewed. Consumption of well water [adjusted odds ratio (aOR) 4.3, 95% confidence interval (CI) 1.6-11.2] and reptile or amphibian contact (aOR 2.6, 95% CI 0.9-7.1) were associated with infection. Consumption of tomatoes (aOR 0.5, 95% CI 0.3-0.9) and poultry (aOR 0.5, 95% CI 0.2-1.0) were protective. Our study suggests that environmental factors are associated with S. Javiana infections in Georgia and Tennessee.

Use of well persons as the comparison group for laboratory-confirmed cases of sporadic salmonellosis may introduce ascertainment bias into case-control studies. Data from the 1996-1997 FoodNet case-control study of laboratory-confirmed Salmonella serogroups B and D infection were used to estimate the effect of specific behaviours and foods on infection with Salmonella serotype Enteritidis (SE). Persons with laboratory-confirmed Salmonella of other serotypes acted as the comparison group. The analysis included 173 SE cases and 268 non-SE controls. SE was associated with international travel, consumption of chicken prepared outside the home, and consumption of undercooked eggs prepared outside the home in the 5 days prior to diarrhoea onset. SE phage type 4 was associated with international travel and consumption of undercooked eggs prepared outside the home. The use of ill controls can be a useful tool in identifying risk factors for sporadic cases of Salmonella.

To monitor risk factors for illness, we conducted a case-control study of sporadic Shiga toxin-producing Escherichia coli O157 (STEC O157) infections in 1999-2000. Laboratory-confirmed cases of STEC O157 infection were identified through active laboratory surveillance in all or part of seven states. Patients and age-matched controls were interviewed by telephone using a standard questionnaire. Information was collected on demographics, clinical illness, and exposures to food, water, and animals in the 7 days before the patient's illness onset. During the 12-month study, 283 patients and 534 controls were enrolled. STEC O157 infection was associated with eating pink hamburgers, drinking untreated surface water, and contact with cattle. Eating produce was inversely associated with infection. Direct or indirect contact with cattle waste continues to be a leading identified source of sporadic STEC O157 infections.

Active surveillance for laboratory-confirmed Salmonella serotype Enteritidis (SE) infection revealed a decline in incidence in the 1990s, followed by an increase starting in 2000. We sought to determine if the fluctuation in SE incidence could be explained by changes in foodborne sources of infection. We conducted a population-based case-control study of sporadic SE infection in five of the Foodborne Diseases Active Surveillance Network (FoodNet) sites during a 12-month period in 2002-2003. A total of 218 cases and 742 controls were enrolled. Sixty-seven (31%) of the 218 case-patients and six (1%) of the 742 controls reported travel outside the United States during the 5 days before the case's illness onset (OR 53, 95% CI 23-125). Eighty-one percent of cases with SE phage type 4 travelled internationally. Among persons who did not travel internationally, eating chicken prepared outside the home and undercooked eggs inside the home were associated with SE infections. Contact with birds and reptiles was also associated with SE infections. This study supports the findings of previous case-control studies and identifies risk factors associated with specific phage types and molecular subtypes.