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Serum samples were obtained from 215 farm-resident children and 396 non-farm-resident children living in a defined rural Wisconsin population. Antibodies to Campylobacter jejuni and Escherichia coli O157:H7 lipopolysaccharide (O157 LPS) immunoglobulin G were measured, and the incidence of clinic visits for diarrheal illness was determined. Risk factors were assessed in a telephone interview. There were 363 children (59%) with C. jejuni antibodies (seropositive for >or=2 immunoglobulin classes) and 86 (14%) with O157 LPS antibodies. Increasing age and farm residence were independently associated with C. jejuni seropositivity by multivariate analysis. O157 LPS antibodies were independently associated with increasing age, female sex, manure contact, and sheep contact. The incidence of clinically recognized diarrhea was similar among children with and without antibodies to C. jejuni and O157 LPS, but the clinic visit rate for diarrhea was 46% lower among farm-resident children. These results are consistent with reduced occurrence of clinical illness from repeated antigenic stimulation in a farm environment.

The frequency of Shiga toxin-producing Escherichia coli (STEC) serotypes associated with postdiarrheal hemolytic uremic syndrome (HUS) cases among children and adults in the United States and the proportion with IgM or IgG lipopolysaccharide antibodies to E. coli O157 were determined by use of a nationwide sample from January 1987 through December 1991. Among 83 patients, STEC were isolated from 30 (43%) of 70 whose stool cultures yielded bacterial growth (25 E. coli O157 isolates and 5 non-O157 STEC isolates). Fifty-three (80%) of 66 patients with serum samples had positive O157 lipopolysaccharide antibody titers. Of the 83 patients, 60 (72%) had evidence of STEC infection, including 6 of 8 adults whose illnesses also met criteria for thrombotic thrombocytopenic purpura. Data from a subset of patients suggest that E. coli O157 was the cause of > or = 80% of the STEC infections. All 3 women who were postpartum had evidence of E. coli O157 infection. STEC infection should be considered the likely cause for all persons with postdiarrheal HUS.

A cluster of gastrointestinal illnesses, including one case of hemolytic-uremic syndrome and one culture-confirmed Escherichia coli O157:H7 infection, followed a trailer park pool party. We interviewed a cohort of party attendees and park residents. A primary case was defined as the first gastrointestinal illness within a household between 5 July and 20 July in which the titer of IgG antibody to E. coli O157 (if determined) was elevated. Of 51 party attendees and trailer park residents, 18 developed a gastrointestinal illness, including 10 who met the definition of a primary case. Swimming in the pool significantly increased the risk of primary illness (relative risk = 6.3; 95% confidence interval = 1.8-18.9). No other exposure was significantly associated with primary illness, after pool exposure was controlled for. The implicated pool had little to no chlorine added during the period of 4-10 July. This outbreak provides new evidence of the importance of proper pool maintenance in controlling the spread of E. coli O157:H7.

In July 1995, 40 Montana residents were identified with laboratory-confirmed Escherichia coli O157:H7 infection; 52 residents had bloody diarrhea without laboratory confirmation. The median age of those with laboratory-confirmed cases was 42 years (range, 4- 86); 58% were female. Thirteen patients were hospitalized, and 1 developed hemolytic-uremic syndrome. A case-control study showed that 19 (70%) of 27 patients but only 8 (17%) of 46 controls reported eating purchased (not home-grown) leaf lettuce before illness (matched odds ratio, 25.3; 95% confidence interval, 3.9-1065.6). Pulsed-field gel electrophoresis identified a common strain among 22 of 23 isolates tested. Implicated lettuce was traced to two sources: a local Montana farm and six farms in Washington State that shipped under the same label. This outbreak highlights the increasing importance of fresh produce as a vehicle in foodborne illness. Sanitary growing and handling procedures are necessary to prevent these infections.

Between 23 June and 15 July 1994, 21 cases (19 primary and 2 secondary) of Escherichia coli O157:H7 infection were identified in the Bethel, Connecticut, area. Three pulsed-field gel electrophoresis (PFGE) patterns from 15 isolates (I, n = 13; II, n = 2; and III, n = 1) were observed. A case-control study that excluded secondary cases and patients with PFGE II and III patterns (n = 16) demonstrated that consumption of food from one supermarket was associated with illness (15/16 cases vs. 31/47 geographically matched controls, odds ratio [OR] undefined, lower 95% confidence interval OR = 1.45, P = .018). No one food was associated with illness. Inspection of the supermarket revealed deficiencies in hygiene and meat handling practices. The 2 cases with PFGE II ate raw beef and raw lamb from a second supermarket. These outbreaks demonstrate the value of PFGE in supporting epidemiologic investigations and the potential for outbreaks arising from retail outlets.

Active surveillance for invasive meningococcal disease was conducted during 1986 and 1987 in six areas of the United States with a total population of approximately 34 million persons. The incidence of meningococcal disease was 1.3:10(5). The highest incidence of disease among the surveillance areas was in Los Angeles County (1.65:10(5). Neisseria meningitidis serogroups B and C caused about equal amounts of disease, which reflects a recent increase in the incidence of group C disease. Group C caused more than half of the cases of meningococcal disease in Los Angeles and Tennessee but less than one-third of the cases in Missouri and Oklahoma. Multilocus enzyme electrophoresis demonstrated that a group of closely related isolates of N. meningitidis was prevalent in Los Angeles during the surveillance period and was associated with an increased incidence of meningococcal disease there.

To determine the morbidity and mortality due to listeriosis in the United States, the authors undertook an active surveillance project in 1986 to identify all cases in which Listeria monocytogenes was isolated from cultures of ordinarily sterile sites in a population of 34 million persons. The authors estimated that at least 1,700 cases of listeriosis and 450 deaths occurred in the United States in 1986; 27% of these cases occurred in pregnant women, with 22% of perinatal cases resulting in stillbirths or neonatal deaths. The risk of listeriosis in adults (0.5 per 100,000 population) was similar in all regions studied; the incidence of perinatal listeriosis was three times higher in Los Angeles County, California, than in the other areas (24.3/100,000 live births vs. 7.8/100,000 live births). Geographic variation may have resulted from underdiagnosis of perinatal listeriosis in five of the study areas. Multilocus electrophoretic enzyme typing was useful for elucidating the molecular epidemiology of L. monocytogenes; perinatal listeriosis was significantly associated with one group of related strains. Multilocus electrophoretic enzyme typing also identified three clusters representing possible common-source outbreaks. These findings document the substantial morbidity due to listeriosis in the United States; to the extent that sporadic listeriosis is foodborne, this morbidity could be reduced by appropriate preventive measures, particularly in persons known to be at increased risk of infection.

From December 1986 to March 1987 an outbreak of Listeria monocytogenes infection occurred in the Philadelphia metropolitan area. A patient-control study showed patients were more likely than controls to have had an ill family member and to have used antidiarrheal medication during the month before their illness. Diet histories showed patients were significantly more likely to have eaten ice cream or salami than were controls, and to have shopped at one grocery store chain. Subtyping of L. monocytogenes isolates of patients showed no predominant strain, and cultures of food products eaten by patients were negative except for Brie cheese eaten by one patient. With no predominant strain of L. monocytogenes in the patients, a common source for this outbreak is unlikely. Thus, the identified risk factors may have been associated with carriage of L. monocytogenes and a coinfecting organism may have precipitated disseminated disease. Possible cofactors should be considered in investigations of future outbreaks of listeriosis.

Using a panel of nine monoclonal antibodies, we subgrouped 85 environmental and 129 clinical Legionella pneumophila serogroup 1 isolates from Paris, France. Patients were unlikely to be epidemiologically linked either with each other or with the 44 sampled environmental sites (14 air conditioning systems and 30 buildings) that were selected at random in the Paris area. According to their monoclonal antibody patterns, isolates belonged to 14 subgroups. Monoclonal antibody 2 recognized 121 (93.8%) of 129 clinical isolates and 30 (35.3%) of 85 environmental isolates (P less than 10(-9)). Of the eight patients infected with L. pneumophila not recognized with monoclonal antibody 2, seven were immunocompromised; only 46.3% of the 121 patients infected with L. pneumophila reactive with monoclonal antibody 2 were immunocompromised (P = .02). We conclude that monoclonal antibody 2 can be used as a marker for the more virulent strains of L. pneumophila serogroup 1.