Older women with chronic cytomegalovirus (CMV), a lifelong viral infection, are three times frailer than those who did not have the infection, US scientists have found.

The scientists did extensive research to demonstrate the association between CMV and the frailty syndrome, said a press release posted on the science portal EurekAlert.

The study also revealed that women who had the viral infection and high levels of interleukin-6 (IL-6), a marker of inflammatory response, are likely to be frailer.

"It is not clear why, with age, some people become frail, but frailty has been linked to inflammation," said Heidi N. Schmaltz, one of the researchers.

"Patients who are frail are more likely to be hospitalised, fall, develop disability and die than their peers. Thus it is critical to understand what causes people to become frail and what potential treatments could decrease the risk of poor outcomes in those who are frail, particularly with the aging population," Schmaltz said.

The study published in the Journal of the American Geriatrics Society surveyed over 700 female participants aged 70 to 79 years.