Key Point

Influenza-like illness in nursing home residents is not exclusive to influenza A infection but has a nonspecific clinical presentation, which is caused by a variety of viral and/or bacterial agents.

Influenza-like illness (ILI), a common cause of hospitalization among elderly people living in residential care homes, has a nonspecific clinical presentation and is typically caused by bacterial and viral agents other than influenza, according to David Shu Cheong Hui, MD, from the Department of Medicine and Therapeutics at the Chinese University of Hong Kong, and colleagues. .

In a prospective study, four residential care homes in the Shatin district of Hong Kong were monitored daily from April 2006 to March 2007 for the occurrence of ILI in a total of 771 residents. ILI was defined as having a temperature of 37.8°C (100.0°F) or higher or an acute deterioration in physical or mental ability, plus either new onset of one or more respiratory symptoms or an acute worsening of a chronic condition with respiratory symptoms.

ILI occurred in 194 participants, for a total of 259 episodes. There were mild peaks in incidence in January to March and April to June, but overall the level stayed consistent throughout the year. An infectious agent was identified in 61.4% of all episodes. The most common organism was Streptococcus pneumonia, followed by respiratory syncytial virus, Pseudomonas aeruginosa, human metapneumovirus, and parainfluenza virus types 1 and 3. ILI symptoms were nonspecific, and none of them correlated to any particular etiological agent. “No association was observed between influenza vaccination status and underlying aetiology, clinical features, or outcome,” the researchers noted.

Although the study was not designed to question vaccine efficacy or the severity of illness or comorbidities, it “yielded a very high rate of organism identification, and information collected will be useful to guide future clinical management,” the authors concluded.

—Lissa Edmond

Suggested Reading
Hui DS, Woo J, Hui E, et al. Influenza-like illness in residential care homes. Thorax. 2008;63(8):690-697.

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