Vibrio parahaemolyticus infections are associated with consumption of raw or undercooked shellfish, contaminated food, and exposure of wounds to warm seawater. Foodborne outbreaks and sporadic infections from Vibrio species in 4 Gulf Coast states are reported routinely to the Centers for Disease Control and Prevention (CDC). Between 1988 and 1997, 345 sporadic V. parahaemolyticus infections were reported: 59% were gastroenteritis, 34% were wound infections, 5% were septicemia, and 2% were from other exposures. Forty-five percent of patients suffering from these conditions were hospitalized for their infections, and 88% of persons with acute gastroenteritis reported having eaten raw oysters during the week before their illness occurred. Between 1973 and 1998, 40 outbreaks of V. parahaemolyticus infections were reported to the CDC, and these outbreaks included >1000 illnesses. Most of these outbreaks occurred during the warmer months and were attributed to seafood, particularly shellfish. The median attack rate among persons who consumed the implicated seafood was 56%. To prevent V. parahaemolyticus infections, persons should avoid consumption of raw or undercooked shellfish and exposure of wounds to seawater.

Salmonellosis is a major cause of illness in the United States. To highlight recent trends, data for 1987-1997 from the National Salmonella Surveillance System were analyzed. A total of 441,863 Salmonella isolates were reported, with the highest age-specific rate among infants (159/100,000 infants at 2 months). Annual isolation rates decreased from 19 to 13/100,000 persons; however, trends varied by serotype. The isolation rate of Salmonella serotype Enteritidis increased until 1996, whereas declines were noted in Salmonella serotypes Hadar and Heidelberg. Overall, serotypes that increased in frequency were significantly more likely than those that decreased to be associated with reptiles (P=.008). Salmonella infections continue to be an important cause of illness, especially among infants. Recent declines in food-associated serotypes may reflect changes in the meat, poultry, and egg industries that preceded or anticipated the 1996 implementation of pathogen-reduction programs. Additional educational efforts are needed to control the emergence of reptile-associated salmonellosis.

The etiologic agents and food vehicles associated with the 7458 outbreaks (involving 237,545 cases) of foodborne disease reported to the Centers for Disease Control between 1973 and 1987 were examined. Bacterial pathogens accounted for 66% of outbreaks and 87% of cases, viruses 5 and 9%, parasites 5 and <1%, and chemicals 25 and 4%, respectively. Salmonella accounted for 42% of outbreaks and 51% of cases due to bacterial pathogens. When data from 1973–75 were compared with 1985–87, a 75% increase in the proportion of outbreaks and 130% increase in the proportion of cases due to Salmonella were observed; in particular, outbreaks due to Salmonella enteritidis increased markedly. The proportion of Salmonella outbreaks with a known vehicle that were associated with beef (the food most frequently associated with Salmonella outbreaks) peaked at 30% in 1981, dropped to 4% in 1982, and has since risen gradually. The proportion of Salmonella outbreaks due to chicken and eggs increased over the study period. Bacteria not previously recognized as important foodborne pathogens that emerged during the study period include Campylobacter jejuni, Escherichia coli 0157:H7, and Listeria monocytogenes. Bacterial pathogens accounted for 90% of deaths, with L. monocytogenes (317/1,000 cases) and Clostridium botulinum (192/1,000 cases) having the highest death-to-case ratios. The proportion of outbreaks in which the food was prepared in a commercial or institutional establishment and the median outbreak size both increased. Investigation and analysis of foodborne disease outbreaks continue to play a key role in understanding foodborne illness and in designing and evaluating control measures.

Data collected by the CDC through a collaborative surveillance program for collection and periodic reporting of data concerning the occurrence and causes of foodborne disease outbreaks (FBDOs) are reviewed for the period from January 1988 through December 1992. An FBDO is defined as the occurrence of two or more cases of a similar illness resulting from the ingestion of a common food. Before 1992 only one case of intoxication by chemical or other nonbacterial toxin, marine toxin, or Clostridium botulinum toxin as a result of the ingestion of food was required to constitute an FBDO. Since 1992 two or more cases have been required. State and local public health departments have primary responsibility for identifying and investigating FBDOs. State and territorial health departments report these outbreaks to CDC on a standard form. During the 1988–1992 period a total of 2,423 outbreaks of foodborne disease were reported (451 in 1988, 505 in 1989, 532 in 1990, 528 in 1991, and 407 in 1992). These outbreaks caused a reported 77,373 persons to become ill. Among outbreaks for which the etiology was determined, bacterial pathogens caused the largest percentage of outbreaks (79%) and the largest percentage of cases (90%). Salmonella serotype Enteritidis accounted for the largest number of outbreaks, cases, and deaths; most of these outbreaks were attributed to eating undercooked, infected eggs. Chemical and other nonbacterial agents caused 14% of outbreaks and 2% of cases; parasites, 2% of outbreaks and 1% of cases; and viruses, 4% of outbreaks and 6% of cases. The number of FBDOs reported per year did not change substantially during the first four years but declined in 1992 as a result of the revised definition of an outbreak. During this reporting period S. Enteritidis continued to be a major cause of morbidity and mortality. In addition, multistate outbreaks caused by contaminated produce and outbreaks caused by Escherichia coli O157:H7 became more prominent.

An outbreak of Salmonella serotype stanley infections occurred in the United States and Finland in 1995. The outbreak was investigated through case-control studies in Arizona, Michigan, and Finland; by isolate subtyping; and by tracing and culturing of the implicated food. Alfalfa sprout consumption was the only exposure associated with S. stanley infections in Arizona (matched odds ratio [MOR] = 11.1; 95% confidence interval [CI], 1.4-513), Michigan (MOR = 5.5; CI, 1.6-23), and Finland (MOR undefined; CI, 4.9-infinity). US and Finnish patient isolates were a unique outbreak strain distinct from S. stanley isolates not linked to the outbreak. Alfalfa sprouts eaten by patients in 6 US states and Finland were traced to seed shipped by a Dutch shipper. Thus, it was concluded that alfalfa sprouts grown from contaminated seed caused an international outbreak of > or =242 S. stanley infections in > or =17 US states and Finland. This outbreak illustrates a new mechanism through which contamination of fresh produce can cause large, widely dispersed outbreaks.

, a case-control study designed to identify risk factors for sporadic infections with thermotolerant Campylobacter bacteria was conducted in three counties in southeastern Norway. The investigation was confined to infections which were acquired in Norway. A total of 52 bacteriologically confirmed cases and 103 controls matched by age, sex, and geographic region were interviewed. The following risk factors were found to be independently associated with illness in conditional logistic regression analysis: consumption of sausages at a barbecue (odds ratio [OR] = 7.64; P = 0.005), daily contact with a dog (OR = 4.26; P = 0.024), and eating of poultry which was brought into the house raw (frozen or refrigerated) (OR = 3.20; P = 0.024). The risk associated with consumption of sausages at a barbecue could not be attributed to cross-contamination from poultry products. By univariate analysis, consumption of poultry which was bought raw and frozen was associated with illness (OR = 2.42; P = 0.042), even though freezing substantially reduces the number of viable campylobacters. When poultry consumption was examined by countIy of origin, eating of poultry produced in Denmark or Sweden was strongly associated with illness (OR = 13.66; P = 0.014), whereas consumption of poultry produced in Norway was not (OR = 1.33; P = 0.41).

SUMMARYTo determine risk factors for cholera in an epidemic-disease area in South America, a case-control investigation was performed in Guayaquil, Ecuador, in July 1991. Residents > 5 years old who were hospitalized for treatment of acute, watery diarrhoea and two matched controls for each were interviewed regarding sources of water and food, and eating, drinking, and hygienic habits. Interviewers inspected homes of case-patients and controls to document water treatment, foodhandling, and hygienic practices. Faecal specimens and shellfish were cultured for Vibrio cholerae 0 1. Isolates were tested for susceptibility to a variety of antimicrobial agents. Drinking unboiled water (odds ratio [OR] = 4 0, confidence interval [CI] = 1 8-7 5), drinking a beverage from a street vendor (OR = 2-8, CI = 1-3-5-9), eating raw seafood (OR = 3.4, CI = 1P4-11-5), and eating cooked crab (OR = 5.1, CI = 1P4-19-2) were associated with illness. Always boiling drinking water at home (OR = 05, CI = 02-0-9) was protective against illness. The presence of soap in either the kitchen (OR = 03, CI = 0-2-08) or bathroom (OR = 04, CI = 02-09) at home was also protective. V. cholerae 0 1 was recovered from a pooled sample of a bivalve mollusc and from 68 % of stool samples from case-patients. Thirty-six percent of the isolates from stool specimens were resistant to multiple antimicrobial agents. Specific prevention measures may prevent transmission through these vehicles in the future. The appearance of antimicrobial resistance suggests the need for changes in current methods of prevention and treatment.

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