OBJECTIVES: A 1993 large water-borne outbreak of Salmonella typhimurium infections in Gideon, Mo, a city of 1100 with an unchlorinated community water supply, was investigated to determine the source of contamination and the effectiveness of an order to boil water. METHODS: A survey of household members in Gideon and the surrounding township produced information on diarrheal illness, water consumption, and compliance with the boil water order. RESULTS: More than 650 persons were ill; 15 were hospitalized, and 7 died. Persons consuming city water were more likely to be ill (relative risk [RR] = 9.1, 95% confidence interval [CI] = 2.9, 28.4), and the attack rate increased with increased water consumption. S. typhimurium was recovered from samples taken from a city fire hydrant and a water storage tower. Persons in 31% (30/ 98) of city households had drunk unboiled water after being informed about the boil water order, including 14 individuals who subsequently became ill. Reasons for noncompliance included "not remembering" (44%) and "disbelieving" (25%) the order. CONCLUSIONS: Communities with deteriorating water systems risk widespread illness unless water supplies are properly operated and maintained. Effective education to improve compliance during boil water orders is needed.

Leptospirosis is a risk for swine producers and slaughterhouse workers, and may be prevented through appropriate hygiene, sanitation, and animal husbandry. It is essential to educate people working with animals or animal tissues about measures for reducing the risk of exposure to zoonotic pathogens.

Two term neonates born within four days of each other at a small hospital developed sepsis and meningitis caused by a unique strain of Citrobacter diversus not previously reported to cause meningitis. Eleven (27.5%) of 40 other infants admitted to the nursery during the epidemic period developed rectal or umbilical colonization by C. diversus. Contact soon after birth with either of two nurses was more common among infected or colonized infants than among infants who were not infected or colonized. Hand cultures of both nurses and a rectal culture of one of the nurses yielded the epidemic strain. C. diversus may have been introduced into the nursery by the rectal carrier and spread person to person. Six weeks later continued surveillance identified a second cluster (of four colonized infants) associated with a mother who was a carrier of C. diversus and whose newborn infant became colonized at birth. The outbreak ended after strict control measures were used.

In the summer of 1981, an outbreak of diarrhea occurred in students and staff at a school for mentally retarded adults and children in Columbia, Missouri. Forty-one (48%) of 86 students and 38 (28%) of 137 staff members in the two dormitories with the lowest functioning students were ill. Enteroinvasive Escherichia coli 0124:H30 was isolated from 20 persons including six staff members, 13 students, and the ill mother of one of the students. Contact with students was associated with illness. Thirty-eight (33%) of the 115 student-care staff members and none of the 22 nonstudent-care staff members who worked in the two dormitories were ill (p = 0.004, chi-square). In the dormitory with the most dependent students, illness in student-care staff was associated with the number of contacts with ill students and with having taken a student home during the outbreak. Control measures to interrupt transmission included separation of symptomatic or culture-positive students from those who were well, and emphasizing handwashing. The authors present these findings as the first report of person-to-person transmission in an outbreak of enteroinvasive E. coli.

Recent data have suggested that there are racial differences in the susceptibility to infection by Mycobacterium tuberculosis. An opportunity to test this suggestion was afforded by an outbreak of tuberculosis in a racially mixed elementary school in St. Louis County, Missouri. A physical education teacher was discovered to have cavitary pulmonary tuberculosis. Of 343 students in the school, 176 (51 percent) were found to be tuberculin skin test positive (> or = 5 mm induration by Mantoux method); 32 children had abnormal chest radiographs. More frequent contact with the physical education teacher was associated with infection (p < 0.001). Black children were no more likely to be infected than were white children (relative risk (RR) = 0.98, 95% confidence interval (CI) 0.78-1.22). However, black children who were tuberculin positive had larger skin reactions than did white children (mean, 18.9 vs. 16.6 mm, p < 0.001) and were more likely to have abnormal chest radiographs (RR = 2.76, 95% CI 1.44-5.27). Among tuberculin-positive children, low body mass index (less than 10th percentile) was associated with active disease (RR = 2.90, 95% CI 1.45-5.80). The analysis of race was unchanged after controlling for sex, body build, and level of contact with the physical education teacher. Widespread tuberculous infection resulted from contact with a highly infectious staff person. Thin body build was a risk factor for active disease. Black children were no more susceptible to infection than were white children, although they more commonly developed radiographic evidence of active disease.