In elderly adults and patients with cardiopulmonary disease, infection with respiratory syncytial virus (RSV) is an illness on a par with influenza A, according to a report in the April 28th The New England Journal of Medicine.

Previous research has suggested that RSV is a potentially serious problem in older adults, but the extent of illness has not been accurately assessed, lead author Dr. Ann R. Falsey, at the University of Rochester School of Medicine and Dentistry in New York, and her team note.

To investigate, Falsey’s group followed two prospective groups: 608 healthy persons age 65 or older and 540 adults diagnosed with congestive heart failure or Chronic obstructive pulmonary disease. They also review the records of 1,388 patients age 65 or older or who had underlying cardiopulmonary disease and were hospitalized for treatment.

During four consecutive winters between 1999 and 2003, RSV was identified in 102 illnesses among patients in the prospective groups and in 142 cases involving hospitalized patients. Corresponding numbers for influenza A were 44 and 154. Annual rates of RSV infection were 3 percent to 7 percent among healthy elderly subjects and 4 percent to 10 percent among those at high risk.

In the prospective study groups, one quarter of healthy elderly patients and nearly half of high-risk patients sought medical attention for RSV infection. Sixteen percent of those at high risk required hospitalization.

Among hospitalized patients, RSV and influenza A resulted in similar lengths of stay, rates of intensive care use, and mortality (8 percent in the RSV patients and 7 percent in influenza patients).

The authors estimate that RSV infection leads to approximately 177,000 hospital admissions per year in the US and 14,000 annual deaths. On the basis of these data, hospitalization costs would exceed $1 billion annually.

These findings “should lead to increased vigilance for this infection on the part of the clinician,” Drs. Sanjay Sethi and Timothy F. Murphy, at the State University of New York in Buffalo, write in a related editorial, although treatment at this point is largely supportive. Perhaps even more important, they say, are efforts to develop an effective RSV vaccine.

The New England Journal of Medicine, April 28, 2005.