In September 1985, an outbreak of Escherichia coli O157:H7 enteritis affected 55 of 169 residents and 18 of 137 staff members at a nursing home. The outbreak was characterized by two phases: a primary wave whose source was probably a contaminated sandwich meal and a secondary wave compatible with person-to-person transmission of infection. Among the elderly residents, the incubation period was 4 to 9 days (mean, 5.7 +/- 1.2). Older age and previous gastrectomy increased the risk of acquiring the infection (P = 0.01 and 0.03, respectively). Antibiotic therapy during exposure was associated with acquiring a secondary infection (P = 0.001). Hemolytic uremic syndrome developed in 12 affected residents (22 percent), 11 of whom died. Overall, 19 (35 percent) of the affected residents died, 17 (31 percent) from causes attributable to their infection. Antibiotic therapy after the onset of symptoms was associated with a higher case fatality rate in the more severe cases, possibly because patients with more severe disease tended to be treated with antibiotics. There were no complications or deaths among the affected members of the staff. Evidence of infection by verotoxin-producing E. coli O157:H7 was detected in 30 of 70 cases on the basis of isolation of this organism or demonstration of free verotoxin in stools. All isolates belonged to the same phage type. The high morbidity and mortality associated with this condition emphasize the need for proper food hygiene, rapid identification of outbreaks of disease, and prompt institution of infection-control techniques among the institutionalized elderly.

A case-control study, using both matched and unmatched controls, was carried out on individuals who were injured or killed by a series of tornadoes that passed through Ontario, Canada, on May 31, 1985. Many serious injuries (25%) and almost all (83%) deaths were the result of becoming airborne, while most minor injuries (94%) were due to being struck by objects. Head injury was the most common injury type. Few (21%) of those in buildings chose the recommended location, and most (61%) were not in the least damaged part. Most (91%) had less than one minute's warning, and only 47% had a functioning radio at the time the tornado hit. The following risk factors for injury and death were identified: poor building anchorage; location other than in a basement, especially outdoors; age over 70 years; and high wind strength. These findings support previous findings and point to measures which have potential for preventing death or serious injury in future tornadoes: adequate warning systems and public education to ensure that individuals understand the warning and respond by seeking appropriate shelter. Those in adequately anchored buildings should shelter in an interior room or basement. Those who are outdoors, in poorly anchored buildings, mobile homes, or portable classrooms require access to an adequately anchored building, preferably with a basement, during severe storm warnings. This should be arranged by local authorities.