A statewide survey of immunization rates in Minnesota school age children: implications for targeted assessment and prevention strategies

BACKGROUND

A retrospective statewide immunization survey of the 69115 Minnesota children who entered kindergarten in 1992 was conducted.

METHODS

Information was collected from school immunization records on date of birth, dates of vaccination for each dose of vaccine, address of residence and race/ethnicity (when available). Immunization rates were assessed retrospectively for each month of a child's life from 2 to 48 months of age. Age-appropriate immunization was defined as receipt of all scheduled vaccines within 30 days of the recommended age.

RESULTS

Immunization levels varied by vaccine, age of the child and race/ethnicity. For example at 19 months of age, 73% of students had received measles, mumps, rubella vaccine; however, only 39% had received their fourth dose of diphtheria, tetanus and pertussis vaccine. White, non-Hispanic students consistently had higher vaccination rates than children of other racial/ ethnic groups. For example 45% of white, non-Hispanic students were age-appropriately vaccinated at 16 months of age compared with 25% of Blacks, 30% of American Indians, 30% of white Hispanics and 28% of Asian-Pacific Islanders (Mantel-Haenzel chi square, P < 0.001 for each comparison). Furthermore coverage rates frequently varied significantly by neighborhood, thereby identifying pockets of underimmunization within communities.

CONCLUSION

Our data demonstrate that vaccination rates can vary substantially by age, race/ ethnicity and neighborhood. Detailed immunization assessment is necessary so that effective targeted interventions can be developed.

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.

An outbreak of Salmonella enteritidis infection at a fast-food restaurant: implications for foodhandler-associated transmission

An outbreak of Salmonella enteritidis infection occurred in patrons and employees of a fast-food restaurant. Transmission took place over a 9-day period. A single employee (employee A) was identified who had onset of gastrointestinal illness 1 day before the first reported patron exposures and had S. enteritidis isolated from stool. A case-control study of 37 ill and 20 healthy patrons who ate during shifts worked by employee A demonstrated that curly-fried potatoes and ice (odds ratio [OR], 6.8; 95% confidence interval [CI], 1.5-33.7; P = .007), both food items handled bare-handed by employee A, were associated with illness. Employees who worked two or more shifts with employee A were more likely to be infected than those who did not work with employee A (OR, 4.4; CI, 1.0-19.5; P = .03). Foodhandlers who subsequently became infected apparently contaminated multiple food items with additional transmission to patrons. This outbreak illustrates the potential for foodhandlers in a fast-food restaurant setting who are infected with Salmonella to be a source of transmission.

An outbreak of Escherichia coli O157:H7 colitis associated with consumption of precooked meat patties

An outbreak of Escherichia coli O157:H7 hemorrhagic colitis at a Minnesota junior high school in October 1988 comprised 32 cases among 1562 students (attack rate, 2.0%). Four children were hospitalized; none developed hemolytic-uremic syndrome. Case children were more likely than controls to have eaten heat-processed meat patties (odds ratio, 6.2; 95% confidence interval, 2.0-20.1; P less than .001) in the school cafeteria on a specific day. The minimum estimated attack rate among students who ate these patties was 8%. The patties should have been sufficiently cooked by the manufacturer to destroy enteric pathogens before they were frozen and distributed. E. coli were cultured from frozen patties that were manufactured at the same plant on the same dates as the implicated patties, but serotype O157:H7 was not isolated. Heat-processed meat patties may serve as vehicles for E. coli O157:H7 infection, and currently there are no federal or state regulatory standards to ensure the safety of these products.

An outbreak of psittacosis in Minnesota turkey industry workers: implications for modes of transmission and control

From June through November 1986, an outbreak of psittacosis occurred in turkey industry workers in central Minnesota. A total of 186 suspect cases were identified, and 122 cases (66%) were serologically confirmed. Cases occurred in three turkey processing plants, two rendering plants, one farm, and one "further processing" plant (where meat is removed from previously eviscerated carcasses and consumer products, such as roasts, are made). As in previous outbreaks, workers exposed to the viscera of infected birds were at greatest risk of becoming infected. However, our data showed that 31 (25%) of the confirmed cases occurred in workers at the further processing plant who had contact only with previously eviscerated carcasses. Although the specific source of infection and the mode of transmission in these workers are unclear, the use of gloves and masks by all processing workers during an outbreak might help to limit exposure. Control measures, which focused on identifying and treating ill turkey flocks, were initiated in early September; however, cases continued to occur in turkey industry workers through November. One of the flocks suspected of causing illness appeared healthy and, therefore, was not treated. Chlamydia psittaci infection in this flock was confirmed by culture after the flock had been processed. A rapid test for diagnosing C. psittaci infection in turkey flocks at the time of processing might be useful in preventing exposure of large numbers of workers.

A foodborne outbreak of Norwalk virus gastroenteritis. Evidence for post-recovery transmission

From November 10-16, 1982, 220 (57%) of 383 attendees at eight banquets for which food had been prepared at a single hotel restaurant and the employees of the hotel had onset of Norwalk virus gastroenteritis. Epidemiologic investigation of the three largest banquets confirmed consumption of potato and fruit salads (banquet A), coleslaw (banquet B), and tossed salad (banquet C) to be significantly associated with illness. Between November 8-19, similar illness occurred in seven (54%) of 13 hotel kitchen employees. The foods implicated in banquets A and B were prepared by one salad worker during her acute illness and up to 48 hours following her recovery. A second salad worker prepared the implicated tossed salad for banquet C 24 hours following her recovery. To the authors' knowledge, this is the first foodborne outbreak investigation demonstrating Norwalk viral excretion and transmission by a food handler after recovery from illness and either person-to-person or vehicle-borne transmission between food handlers with subsequent transmission by more than one food handler to patrons.

A point-source outbreak of campylobacteriosis associated with consumption of raw milk

After a one-day field trip to a Minnesota farm, 22 (45%) of 49 third-grade students and three (14%) of 21 adult chaperones developed campylobacteriosis. Campylobacter jejuni was isolated from specimens of 13 children and one asymptomatic adult. Illness was associated with the consumption of raw milk during a picnic lunch (odds ratio = 41.0, P less than .0001) and participation in hand milking of cows (odds ratio = 37.5, less than .0001). Two additional findings implicated consumption of raw milk as the vehicle for transmission. First, the odds ratio for illness among those who drank raw milk and did not milk cows was 11.8 (P less than .01), whereas the odds ratio for illness among those who milked cows but did not drink raw milk was only 1.2 (P greater than .02). Second, there was a dose-response relation between the occurrence of illness and the quantity of raw milk consumed (P less than .0001). Neither the median incubation period nor duration of illness was related to the amount of milk consumed. All persons with a stool culture positive for C. jejuni excreted the organism for at least two weeks, but less than six weeks. No secondary cases of illness were documented.

Norwalk gastroenteritis: a community outbreak associated with bakery product consumption

From 23 to 26 August 1982, a gastrointestinal illness occurred among 129 of 248 (52%) persons interviewed who had attended four social events in the Minneapolis-St. Paul area. The median incubation period was 36 hours, and symptoms included diarrhea, nausea, headache, and vomiting. Findings of a food-specific questionnaire given to attendants of the four events confirmed that consumption of cake and frosting was significantly associated with development of the illness (odds ratio, 7.9 to 48.3; p = 0.006 to 0.00001). All cake items were purchased from a single bakery, where the employee who had prepared the frosting had had onset of diarrhea and vomiting on August 20. Given an approximate 60% attack rate among persons who ate frosted items, we estimate that 3000 outbreak-associated cases occurred. Serologic analysis confirmed that 17 of 25 ill persons had fourfold or greater rises in their antibody titer to Norwalk virus. Thus, foodborne transmission of Norwalk virus can result from contamination by a single foodhandler.