Outbreaks of salmonellosis associated with eating uncooked tomatoes: implications for public health. The Investigation Team.

Laboratory-based surveillance of salmonella isolates serotyped at four state health departments (Illinois, Michigan, Minnesota and Wisconsin) led to the identification of multistate outbreaks of salmonella infections during 1990 (176 cases of S. javiana) and 1993 (100 cases of S. montevideo). Community-based case-control studies and product traceback implicated consumption of tomatoes from a single South Carolina tomato packer (Packer A) MOR 16.0; 95% CI2.1, 120.6; P < 0.0001 in 1990 and again in 1993 (MOR 5.7; 95 % CI 1.5, 21.9; P = 0.01) as the likely vehicle. Contamination likely occurred at the packing shed, where field grown tomatoes were dumped into a common water bath. These outbreaks represent part of a growing trend of large geographically dispersed outbreaks caused by sporadic or low-level contamination of widely distributed food items. Controlling contamination of agricultural commodities that are also ready-to-eat foods, particularly fruits and vegetables, presents a major challenge to industry, regulators and public health officials.

Massive outbreak of waterborne cryptosporidium infection in Milwaukee, Wisconsin: recurrence of illness and risk of secondary transmission.

Contamination of the public water supply in Milwaukee during March and April 1993 resulted in a massive outbreak of cryptosporidium infection. We investigated the clinical and epidemiological features of visitors to the Milwaukee area in whom cryptosporidiosis developed, and we conducted a telephone survey of Milwaukee County households to evaluate the risk of recurrent illness and secondary transmission. Cryptosporidium infection during this outbreak generally seemed more severe than cases described in previous reports of large case series. The risk of secondary transmission within a household was low (5%) when the index case involved an adult. The recurrence of watery diarrhea after apparent recovery was a frequent occurrence among visitors with laboratory-confirmed cryptosporidium infection (39%) and among visitors and Milwaukee County residents with clinical infection (21%). The interval between the initial recovery and the onset of recurrence was prolonged (> or = 5 days) in 6%-8% of persons. This pattern of recurrence and its impact on transmission and our understanding of the pathophysiological mechanisms of cryptosporidium infection merit further investigation.

A multistate outbreak of Salmonella javiana and Salmonella oranienburg infections due to consumption of contaminated cheese.

OBJECTIVE: To determine the source of an outbreak of Salmonella javiana and Salmonella oranienburg infections. DESIGN: Laboratory-based statewide surveillance for Salmonella infections and two separate case-control studies. SETTING: Community- and industry-based studies conducted from May through October 1989. PARTICIPANTS: Thirty-one culture-confirmed outbreak-associated cases of S javiana infection and 60 community controls matched for telephone prefix, gender, and age in case-control study I; 50 cases, 100 community controls, and 64 family member controls in case-control study II. RESULTS: One hundred thirty-six culture-confirmed cases of S javiana infection and 11 cases of S oranienburg infection were associated with the outbreak in Minnesota. Outbreak-associated cases were also identified in Wisconsin (15 cases), and in Michigan and New York (one case each). Cases were more likely than controls to have consumed mozzarella cheese manufactured at a single cheese plant (plant X) or cheese that had been shredded at processing plants that also shredded cheese manufactured at plant X (odds ratio [OR], 7.2; 95% confidence interval [CI], 1.7 to 23.2; P < .01). The outbreak-associated strains of both serovars were isolated from two unopened 16-oz (0.45-kg) blocks of mozzarella cheese produced at plant X. The most probable numbers of Salmonella organisms in these samples were 0.36/100 g and 4.3/100 g. CONCLUSIONS: The potential for bacterial pathogen contamination of cheese during manufacture and processing has important epidemiologic implications, particularly because cheese consumption has recently increased in the United States. Low-level contamination of a nationally distributed food product can cause geographically dispersed foodborne outbreaks that may be difficult to detect.

Changes in population density and distribution of Ixodes dammini (Acari: Ixodidae) in Wisconsin during the 1980s.

Changes in the density and distribution of Ixodes dammini, Spielman Clifford, Piesman & Corwin were assessed in Wisconsin by examining hunter-killed deer for ticks in 1981 and 1989. Deer examination sites were distributed widely across the state and included 23 sites in 1981 and 15 sites in 1989; 10 sites were visited both years. Between 1981 and 1989, I. dammini became more abundant throughout its range, and I. dammini range expanded into the southwestern portion of Wisconsin. I. dammini was not found in the eastern one-third of the state. When compared with 1981, the 1989 survey revealed significant increases in the proportion of infested deer in the southwest (Arena), higher levels of infestation of individual deer (number of ticks per individual deer) in the central west (Bangor-W. Salem), and significantly less disparity between the proportions of infested male deer and infested female deer in the north (Spooner) compared with sites farther south. These results are consistent with a pattern of I. dammini range expansion from north to south, followed by an increase in population density in the colonized areas. Dermacentor albipictus Packard was present throughout the range of I. dammini and at sites in the northeastern quadrant of Wisconsin where I. dammini was not found. The range of D. albipictus did not change between the survey years, but its population density increased significantly at sites in the north. There is no evidence for interaction between the two tick species that might affect tick distribution or population density, nor can the greater number of I. dammini found in 1989 be attributed to increased tick activity because of warmer weather; temperatures were cooler in 1989 than 1981.

Kawasaki syndrome in Wisconsin.

We reviewed cases of Kawasaki syndrome reported to the Wisconsin Division of Health and occurring in Wisconsin residents with illness onsets between 1982 and 1989. Of 164 reports, there were 73 confirmed cases that met the Centers for Disease Control case definition criteria for Kawasaki syndrome, 87 probable cases, and four non-cases. Confirmed cases were reported in residents of all five Wisconsin public health regions. The Wisconsin data was demographically similar to national data: 80% of the cases occurred in children younger than 5 years old, the mean annual incidence rate was highest in children 12 to 23 months of age, males were affected more often than females, and the incidence rate was higher among non-white children than among white children. Coronary artery aneurysms occurred in 16% of the patients with confirmed cases. Males developed aneurysms significantly more often than females, and aneurysm formation did not correlate with age. Kawasaki syndrome continues to occur in Wisconsin, and complete and accurate reporting of the disease will enhance the understanding of its natural history and etiology.

Evidence for a high attack rate and efficacy of erythromycin prophylaxis in a pertussis outbreak in a facility for the developmentally disabled.

During an outbreak of pertussis in residents and staff of a facility for the developmentally disabled, 149 persons had laboratory evidence of Bordetella pertussis infection; 130 (87%) reported respiratory illness. Infection rates (IR) in affected wards ranged from 6% to 91%. Most residents were adolescents and adults and had received a full course of diphtheria-tetanus toxoids-pertussis (DTP) vaccine; IRs increased with increasing time after the last DTP dose in fully vaccinated residents. The IR was lower in residents on wards where erythromycin treatment/prophylaxis was started two or fewer weeks after the onset of illness in the first case on the ward (IR, 16%), compared with four or more weeks after onset (IR, 75%; P less than 10(-6)). Respiratory symptoms were milder in ill residents treated within seven days of onset of illness. Although B. pertussis transmission was substantial, erythromycin treatment of patients and prophylaxis of exposed persons was effective in decreasing transmission and disease severity. Carbamazepine toxicity occurred in seven (19%) of 37 residents when carbamazepine was administered with erythromycin.

Aeromonas intestinal infections in the United States.

To evaluate the clinical and epidemiologic aspects of aeromonas enteritis, we studied the cases of 34 persons nationwide from whom Aeromonas hydrophila had been isolated in large numbers from stool in 1984. Compared with 68 control subjects, these patients were more likely to have drunk untreated water, usually from private wells (odds ratio = 20.9; p less than 0.01). Eighteen of the isolates belonged to a single DNA-relatedness group of the eight described for Aeromonas species, but no clear correlation between illnesses in patients and any tested genotypic or phenotypic characteristic of recovered organisms was found. Gastrointestinal complaints tended to be chronic in infected adults and acute and severe in children. Nine patients had become ill after taking antimicrobial agents to which recovered Aeromonas species were resistant; 5 persons took antimicrobials to which their Aeromonas strains were susceptible and had alleviation or resolution of their gastrointestinal symptoms. These findings indicate that at least some Aeromonas strains are enteropathogenic for the normal host and that these organisms are acquired by drinking untreated water.

Kawasaki syndrome: a controlled study of an outbreak in Wisconsin.

The etiology of Kawasaki syndrome remains unestablished, although a possible role has been suggested for exposure to the application of carpet shampoo, house dust mites, and rickettsial infection. During an outbreak of 20 cases of Kawasaki syndrome that occurred in southeastern Wisconsin from November 1982 through March 1983, a case-control study was done of 15 cases and 30 matched controls. The study included questionnaire administration, dust collection from homes, and serum specimen collection. Only one patient had been exposed to a shampooed carpet within 30 days before onset of illness. No differences were noted between cases and controls in the degree of exposure to house dust mite-associated factors in the home, nor in the occurrence, density and species-specific prevalence of house dust mites in the home. Meadow voles exposed to house dust mites from the homes of patients did not develop serologic or pathologic evidence of infection due to rickettsiae in the spotted fever and typhus groups or Coxiella burnetii. Anti-mite-specific immunoglobulin E was not detected in serum specimens from cases or controls. Results from this study do not support hypotheses suggesting that the development of Kawasaki syndrome is associated with exposure to application of carpet shampoo, house dust mites, or rickettsial infection.

Babesiosis in Wisconsin. A new focus of disease transmission.

A confirmed case of human babesiosis was identified in August 1983 in a 54-year-old asplenic Wisconsin resident. Babesia microti was identified as the causative agent by blood smear morphology and hamster inoculation techniques. The patient's wife had clinically confirmed Lyme disease in 1981 and had serologic evidence (immunofluorescent antibody to a B microti titer of 1:1,024) of recent Babesia infection in August 1983. Mice (Peromyscus species) trapped on the patients' property and elsewhere in their Wisconsin county of residence were infected with B microti. Lyme disease and babesiosis have the same tick vector and animal reservoir; serum samples from 116 Wisconsin and Minnesota residents with clinically confirmed Lyme disease between 1980 and 1983 were tested, and none were found to have concurrent Babesia infection. This area of Wisconsin is identified as a new focus for babesiosis transmission, but the risk of transmission seems to be low.

Lyme disease in Wisconsin: epidemiologic, clinical, serologic, and entomologic findings.

In 1980-82, 80 individuals (71 Wisconsin residents) had confirmed Lyme disease (LD-c) reported; 39 additional patients had probable or possible LD. All cases of LD-c occurred during May-November; 73 percent occurred during June-July; 54 (68 percent) occurred in males. The mean age was 38.7 years (range, 7-77 years). Among LD-c patients, likely exposure to the presumed vector Ixodes dammini (ID) occurred in 22 different Wisconsin counties. Antibodies to the ID spirochete that causes LD occurred in 33 of 49 LD-c cases versus 0 of 18 in ill controls (p less than .001) and in 13 of 26 LD-c cases treated with penicillin or tetracycline versus 16 of 19 LD-c cases not treated. Early antibiotic therapy appears to blunt the antibody response to the ID spirochete. Regional tick surveys conducted in Wisconsin during each November in 1979-82 have demonstrated regions of greater density of ID. Utilizing comparable tick collection in these surveys, increases were noted in the percentage of deer with ID from 24 percent (31/128) in 1979 to 38 percent (58/152) in 1981, in the standardized mean value of ID/deer from 1.0 in 1979 to 2.2 in 1981, in the percentage of ID of the total ticks collected from 13 percent in 1979 to 71 percent in 1981, or in the ratio of ID to Dermacentor albipictus ticks from 0.14 in 1979 to 2.44 in 1981. However, a reduction in the density of ID/deer was noted generally throughout Wisconsin in 1982 when compared to 1981. LD is widespread in Wisconsin, with ecologic and clinical features similar to those occurring along the eastern seaboard.

Molecular epidemiology of antibiotic resistance in salmonella from animals and human beings in the United States.

We collected serotyped isolates of salmonella from reference laboratories in the United States, tested their susceptibility to antibiotics, and extracted plasmids from isolates that were resistant to a different combination of antibiotics from each of three serotypes. Restriction-endonuclease digestion showed that within each of the three groups, plasmid molecules from animal and human isolates were often identical or nearly identical. One serotype-plasmid combination appeared to be endemic in cattle in 20 states and infected 26 persons in two states. The human cases, which were not recognizably related except for their common plasmids, appeared to be clustered in time but geographically dispersed, like cases in previous outbreaks spread by food products. These findings suggest that resistance plasmids may be extensively shared between animal and human bacteria, and that spread of multiresistant strains of salmonella among animals and human beings, as observed in Britain, may have been undetected in the United States for lack of comparable surveillance.

Tri-state toxic-shock syndrome study. II. Clinical and laboratory findings.

Clinical and laboratory findings were examined in 80 nonfatal cases of toxic-shock syndrome (TSS) which occurred in women from Minnesota, Wisconsin, and Iowa between October 1, 1979, and September 19, 1980. Among the clinical and laboratory factors reviewed, the presence of physician-diagnosed shock was the factor that most significantly correlated with other organ involvement. Vomiting, mucous membrane hyperemia, myalgias, and abnormal urinalysis were the factors noted to be manifest as frequently in the absence as in the presence of shock. Twenty-seven patients had recurrent episodes of TSS. The use of antistaphylococcal antibiotics during the initial TSS episode and the subsequent discontinuation of tampon use were independently statistically significantly associated with a decreased risk of recurrent illness. Only 44 of 54 patients had cervical/vaginal cultures positive for Staphylococcus aureus, a result indicating that a negative cervical/vaginal culture does not preclude the diagnosis of TSS.

Epidemic Legionnaires' disease. Airborne transmission down a chimney.

Between June 18 and July 9, 1979, Legionnaires' disease (LD) developed in 13 persons who had visited a hotel complex in Wisconsin. All had visited the part of the hotel that contains the restaurants and meeting rooms (building A). Legionnaires' disease occurred in 1% who had been exclusively in the meeting rooms and in 0.1% who had eaten only at the hotel restaurants. Furthermore, 1.5% exposed to meeting room 1 and none of those exposed only to the other meeting rooms had LD. Legionella pneumophila was isolated from water in the cooling tower on top of building A. Located within 5 m downwind of the cooling-tower exhaust, a chimney with an open damper allowed cooling-tower exhaust (as demonstrated by air tracer studies) to enter meeting room 1 via the fireplace. Although cases did not occur after the cooling-tower water was treated by continuous hyperchlorination and the chimney was sealed, a seven-day lag occurred between treatment and elimination of the organism from the tower water.