Photo Credit – CDC PHIL
# 6396
Last Sunday I wrote about this week’s General Meeting of the American Society for Microbiology that was being held in San Francisco, and provided some links to live and archived webcasts (see Webcast: ASM Live San Francisco 2012).
As you might expect, a large number of scientific presentations have been made over the past few days - and we’ve seen a number of press releases highlighting that research - including the one that follows, on just how common the `common cold’ really is.
The surprise here is - that among college students tested over an 8 week period - asymptomatic infections led symptomatic infections by a factor of 4 to 1.
Which suggests that simply staying away from people with cold symptoms may not provide much in the way of protection against rhinoviruses, and makes common sense interventions - such as frequent handwashing - probably even more important.
A few excerpts from the release, but follow the link to read it in its entirety:
Asymptomatic rhinovirus infection outnumbers symptomatic infection 4 to 1 among university students
The common cold virus may be more common than previously thought in university students not reporting any symptoms. Rhinovirus, the virus responsible for the common cold was found at some point during an 8-week study period in an estimated 60% of university students that were asymptomatic. Researchers from Canada report their findings at the 2012 General Meeting of the American Society for Microbiology.
“A high occurrence of asymptomatic infections indicates that university students can spread infections to classmates, or individuals in the community without knowing they are infected,” says Andrea Granados of McMaster University in Hamilton, Ontario, a researcher on the study. The study was conducted at McMaster University and St. Joseph’s Healthcare in Hamilton, Ontario, Canada as part of the McFlu2 COLD3 clinical trial by Granados and colleagues Emma Goodall, Marek Smieja and James Mahony.
Rhinovirus, best known for causing the common cold can also cause bronchitis and trigger asthma attacks.
<SNIP details on how the study was done>
Based on these findings, the researchers estimate that as many as 60.5% of the asymptomatic student population was infected at some time with rhinovirus over an eight week study period.
They also used PCR to determine the viral load in symptomatic and asymptomatic students. Students with asymptomatic rhinovirus infections had significantly less virus than symptomatic infections. Decreased amounts of the virus may be responsible for the lack of symptoms, says Granados, however, larger studies are necessary to confirm this finding.
“In this study, we found that university students with rhinovirus infections who lacked symptoms outnumbered by a factor of 4 the number of infected students with symptoms. The virus particles can be spread by aerosols or direct contact with an asymptomatic individual. 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,” says Granados.
It’s happened to all of us, I suppose.
We come down with a cold, wrack our brains trying to remember coming in contact with someone with the sniffles - and come up with a blank - leaving us to wonder just where the heck we caught it.
Today’s study provides a plausible explanation.
Granted, those with asymptomatic infections showed lower viral loads than those displaying cold symptoms - suggesting that they may be less efficient spreaders of the virus – but we don’t have enough data to know how much of a viral load it takes to spread the virus.
The good news here, I suppose, is that we can sometimes (perhaps often) get one of the numerous rhinoviruses that circulate without necessarily enduring the misery of cold symptoms.
The bad news is, we may be spreading those cold viruses to others while looking, and feeling, perfectly healthy.
