ABSTRACT
CONTEXT: Multidrug-resistant Salmonella Typhimurium DT104 has recently emerged as a cause of human and animal illness in Europe and North America. In early 1997, health officials in Yakima County, Washington, noted a 5-fold increase in salmonellosis among the county's Hispanic population. OBJECTIVES: To characterize bacterial strains and identify risk factors for infection with Salmonella Typhimurium in Yakima County. DESIGN: Laboratory, case-control, and environmental investigations. SETTING AND PARTICIPANTS: Patients with culture-confirmed Salmonella Typhimurium infection living in Yakima County and age- and neighborhood-matched control subjects. MAIN OUTCOME MEASURES: Food vehicle implication based on case-control study and outbreak control. RESULTS: Between January 1 and May 5, 1997, 54 culture-confirmed cases of Salmonella Typhimurium were reported. The median age of patients was 4 years and 91% were Hispanic. Patients reported diarrhea (100%), abdominal cramps (93%), fever (93%), bloody stools (72%), and vomiting (53%); 5 patients (9%) were hospitalized. Twenty-two patients and 61 control subjects were enrolled in the case-control study. Seventeen case patients (77%) reported eating unpasteurized Mexican-style soft cheese in the 7 days before onset of illness compared with 17 control subjects (28%) (matched odds ratio, 32.3; 95% confidence interval, 3.0-874.6). All case-patient isolates were phage definitive type 104 (DT104) (n = 10) or DT104b (n = 12), and 20 (91%) were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline. The cheese produced and eaten by 2 unrelated patients was made with raw milk traced to the same local farm. Milk samples from nearby dairies yielded Salmonella Typhimurium DT104. The incidence of Salmonella Typhimurium infections in Yakima County returned to pre-1992 levels following interventions based on these findings. CONCLUSIONS: Multidrug-resistant Salmonella Typhimurium DT104 emerged as a cause of salmonellosis in Yakima County, and Mexican-style soft cheese made with unpasteurized milk is an important vehicle for Salmonella Typhimurium DT104 transmission. We postulate that recent increases in human salmonellosis reflect the emergence of Salmonella Typhimurium DT104 among dairy cows in the region. Continued efforts are needed to discourage consumption of raw milk products, promote healthier alternatives, and study the ecology of multidrug-resistant Salmonella Typhimurium.
Subject(s)
Cheese/microbiology , Disease Outbreaks , Drug Resistance, Microbial , Drug Resistance, Multiple , Milk/microbiology , Salmonella Food Poisoning/epidemiology , Salmonella typhimurium , Adolescent , Adult , Ampicillin Resistance , Animals , Case-Control Studies , Cheese/poisoning , Child , Child, Preschool , Chloramphenicol Resistance , Electrophoresis, Gel, Pulsed-Field , Epidemiologic Methods , Food Handling , Hispanic or Latino , Humans , Infant , Middle Aged , Milk/poisoning , Risk Factors , Salmonella Food Poisoning/etiology , Salmonella typhimurium/classification , Salmonella typhimurium/drug effects , Salmonella typhimurium/isolation & purification , Serotyping , Sterilization , Streptomycin/pharmacology , Sulfonamides/pharmacology , Tetracycline Resistance , Washington/epidemiologyABSTRACT
An outbreak of serogroup C meningococcal disease occurred in six counties in the State of Washington from January 1989 through mid-1991. This report describes epidemiologic data collected from hospitals and health departments, the results of multilocus enzyme electrophoresis of isolates, and the vaccination of high-risk populations in one county. A total of 45 confirmed or probable cases (10 per 100,000 population) occurred. Infants younger than age 1, Hispanics and American Indians, and low-income populations had high attack rates. Nine (20 percent) patients died. The predominant enzyme type, ET-22, had not been detected previously in Washington. More than 22,000 persons were vaccinated in one of the counties. Major challenges to health care personnel included deciding when and where to employ vaccination, obtaining sufficient vaccine, and responding to public anxiety.
