My daughter and I both have colds right now, which has got me to thinking on something I heard a while back but was never sure was true. Apparently, some say, there are a finite number of viruses that cause the common cold (105 is the number that sticks in my head), and once you get each one, you develop an imunity to it. Logically, this means that once you’ve had a certain number of colds in your life, you’ll never catch another.
Confirm? Debunk?
The number of known rhinoviruses that cause colds in humans is now at least 113, and there may be more yet to be discovered. There are another 100 or so other viruses that can cause the cold (or similar symptoms). Getting over one of these viruses will not always confer lifetime immunity to it. In some cases, immunity lasts only a year or two.
Plus, I imagine we can assume that viruses evolve.
I havent got one for a couple years, maybe I already got them all.
There have been several threads on this, but instead of searching them for you, I’ll briefly state the facts. There are over 500 virus that can cause colds, many of them rhinoviruses, but there are other types too.
There are a finite number, but you cannot build permanent immunity to any of them, since they stimulate an Ig that creates only temporary (30 days or so) immunity. The permanent memory cells are not invoked.
Yep. There are hundreds of viruses that cause the common cold. Presumably more are evolving all the time, but no one’s really bothering to keep track. Because the infection is on mucus membranes, only IgA antibodies are stimulated. Immunity typically lasts only a few months for this type of infection.
So when people ask why there’s no cure for the common cold, the answer is that we probably could cure it. But you’d have to be immunized against a few hundred viruses every few months. One of those cases where the cure is worse than the disease.
Want some facts?
Prepared by:
Office of Communications and Public Liaison
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, MD 20892
http://www.niaid.nih.gov/factsheets/cold.htm