Surveillance for outbreaks of respiratory tract infections in nursing homes

Background: Outbreaks of respiratory tract infections are common in long-te rm care facilities for older people. The objective of lour study was to det ermine both the frequency of such outbreaks and their clinical and epidemio logical features. Methods: Prospective surveillance for outbreaks of respiratory tract infect ions and a retrospective audit of surveillance records were conducted in 5 nursing homes in metropolitan Toronto over 3 years. The clinical manifestat ions of infected residents were identified and microbiological investigatio ns for causal agents were conducted. Results: Sixteen outbreaks, involving 480 of 1313 residents, were identifie d prospectively during 1 144 208 resident-days of surveillance, for an over all rate of 0.42 infections per 1000 resident-days. Another 30 outbreaks, i nvolving 388 residents, were identified retrospectively. Outbreaks occurred year-round, with no seasonal pattern. Pathogens included influenza virus, parainfluenza virus, respiratory syncytial virus, Legionella sainthelensi a nd Chlamydia pneumoniae. Multiple pathogens were detected in 38% (6/16) of the prospectively identified outbreaks. Of the 480 residents in the prospec tively identified outbreaks 398 (83%) had a cough, 194 (40%) had fever and 215 (45%) had coryza. Clinical findings were nonspecific and could not be u sed to distinguish between causal agents. Pneumonia developed in 72 (15%) o f the 480 residents, and 58 (12%) required transfer to hospital. The case-f atality rate was 8% (37/480). Interpretation: Our findings emphasize the importance of adequate surveilla nce for outbreaks of respiratory tract infections in nursing homes and of e arly diagnosis so that appropriate interventions can be promptly instituted .