Respiratory syncytial virus (RSV), primarily seen as a cause of illness in infants and children, often affects the elderly and high-risk adults as much as influenza, a study by University of Rochester Medical Center researchers demonstrates.
Although pediatricians are well aware of RSV, most internists rarely consider RSV in adult patients. However, an estimated 14,000 elderly and high-risk adults die annually from an RSV infection, according to research by Ann R. Falsey, M.D., and Edward E. Walsh, M.D.
RSV infections account for more than 177,500 hospitalizations of adults each year at a cost that exceeds $1 billion.
The study, published in the April 28 edition of the New England Journal of Medicine, confirms the need for the development of an RSV vaccine for elderly and high-risk adults, says Falsey, an associate professor of medicine and the study's principal investigator.
"This in no way diminishes the impact of RSV in children," Falsey says. "For the elderly, RSV can be serious, similar to the flu. Overall, RSV causes a substantial burden of disease in adults. Development of a vaccine would be worthwhile."
While RSV has been recognized as a potentially serious problem for adults for 30 years, there has been limited documentation of the extent of RSV infections. The four-year study by researchers is the first large investigation over a substantial period of time that used state-of-the-art diagnostic techniques.
The study has important repercussions for public health strategy and for the prioritization of the development of vaccines and antiviral agents, according to an editorial accompanying the research article in The New England Journal of Medicine.
RSV is the most common cause of bronchiolitis and pneumonia among infants and children under 1 year of age. But RSV causes repeated infections throughout life. In adults, the symptoms are similar to the common cold, but they are more severe and last longer. The virus is highly contagious, entering the nose or eyes by hands and by direct contact with residue from coughs or sneezes.
Falsey and the research group conducted the study through four consecutive winters from late 1999 to early 2003. The work was done at Rochester General Hospital.
The group followed 1,388 hospitalized patients, 608 healthy people over the age of 65, and 540 adults (older than 21 years of age) who were considered high risk because of a diagnosis of congestive heart failure or chronic pulmonary disease. Diagnosis was confirmed by culture, molecular diagnostics or serologic test. A total of 2,514 illnesses were evaluated.
The impact of RSV infection on both the healthy elderly and the high-risk group was significant. RSV infection, for example, accounted for 10.6 percent of hospitalizations for pneumonia during winter months, 11.4 percent for those with chronic obstructive pulmonary disease, 5.4 percent for congestive heart failure, and 7.2 percent for asthma.
Although RSV disease was somewhat milder when compared to influenza A, RSV infection was more common. The total number of doctor visits and hospitalizations for the two viruses was similar over the four-year period of the study.
Currently, there are only two approved treatments for RSV. One is ribavirin, an antiviral agent administered as an aerosol. Palivuzumab is a prophylactic immune reagent given by injection. Both are licensed only for treatment of children.
The World Health Organization has designated RSV as a high-priority target for vaccine development. The research by Falsey and the group, according to The New England Journal editorial, provide a new understanding of RSV infection in adults and "an impetus to renew research on the treatment and prevention of RSV infection -- progress that is far from satisfactory at the present."
Research and, in some cases, trials of vaccines for RSV are underway. Some work is being done at the UR Medical Center. Falsey says the vaccines are "very promising."
Now that spring has arrived, RSV will fade. Infections generally occur from October to April. In the tropics, RSV appears during the rainy season.
"Nobody really knows why it goes away," Falsey says. "Many theories have to do with cold and crowding but none are entirely satisfactory."
The research group also includes Patricia A. Hennessey, R.N.; Maria A. Formica, M.S.; and Christopher Cox, Ph.D.