Rhinovirus Infection Common Even Among Those Without Symptoms: Study

You could be infected with the common cold virus and not even know it, according to new research.

A study presented at a meeting of the American Society for Microbiology showed that about 60 percent of college students included in the study had rhinovirus, even though they didn't have any cold symptoms, over an eight-week period.

In fact, among everyone who was found to be infected with rhinovirus, the people who didn't show symptoms outnumbered those who did show symptoms four to one.

This is an important finding because even though you may not have symptoms of a cold, that doesn't mean you can't pass it on to others, researchers said.

"The virus particles can be spread by aerosols or direct contact with an asymptomatic individual," study researcher Andrea Granados, of McMaster University, said in a statement. "There is no treatment for the common cold; therefore, frequent hand-washing is important to prevent the spread of the common cold particularly in early fall."

The study included 545 undergraduate students at McMaster, who had nasal swabs conducted once a week between September and October 2010 and September and October 2011 (when colds are common). Everyone was swabbed regardless of whether they had cold symptoms or not, but people who did have cold symptoms were swabbed daily for seven days.

Over those two years, researchers recorded 167 instances of a cold-like illness; 54 percent of people who reported having a cold-like illness had rhinovirus.

To find who had rhinovirus without expressing symptoms, the researchers took 10 percent of swabs from people; who didn't have cold symptoms, and then randomly took 200 swabs from the 2010 collection and 200 swabs from the 2011 collection to test for rhinovirus. Of those, rhinovirus was found on 33 of the swabs (8.25 percent).

Extrapolated out, researchers estimated that to mean about 60.5 percent of people who didn't have any symptoms in the study actually had rhinovirus.

The researchers also found that people who had rhinovirus but didn't have symptoms had less of the virus than those who did have symptoms; however, they said more research is needed to confirm that this finding applies to everyone on a whole.