How does contagion work with the cold and flu?
February 16, 2005 1:20 PM   Subscribe

Cold/Flu Contagion:

1) Is there any truth to the rumor that "once you manifest symptoms, you're no longer contagious?"
2) If you're recovering from one illness, are you more or less suceptible to others? eg: If I've just gotten over a cold, is my immune system weak and susceptible to strep throat? Or is it on high-alert and likely to protect me better?
3) Following on number 2, why don't more people get multiple viruses/bugs at once, or in rapid sequence? Anecdotally, it seems that most people enjoy an interval of good health after recovering from something. Is that true?
posted by scarabic to Health & Fitness (4 answers total)
1) With other infections (Fifth's disease/Parvovirus B19) comes to mine, yes, but with the cold/flu, no. You're shedding virus from infected cells. However, a large number of the symptoms aren't caused by the virus, but by interferons, which are chemicals secreted by immune cells to help clear viral infections.

2) More susceptible to bacterial, I believe. Upper respiratory tract VIRAL infections usually make you more susceptible to a bacterial infection, the thought being the virus is messing with the body's normal cilia/mucous and the ability to clear bacteria. For example, a cold leading to a sinus infection. (Colds are viral, sinusitis is almost all bacterial.)

3) I would imagine that once you've come into contact with the virus that's going around, you clear it, and gain immunity, there's not a whole lot of other new viruses you're being exposed to (that your body isn't able to clear). You're constantly being infected with bacteria; they're all over your skin, live in your teeth, gums, and nose; it's just that your body's pretty damn great about getting rid of them quickly.
posted by gramcracker at 1:39 PM on February 16, 2005

Viruses of these type spread by way of symptoms. Sneezing virus-particle laden body fluids over others is a successful strategy for reproduction.
posted by AlexReynolds at 2:24 PM on February 16, 2005

WebMD backs this up:

Are you contagious before you show symptoms? If a co-worker is sniffing over the phone you share, is he or she contagious then?

The viruses that cause colds and the flu are spread by microscopic droplets from an infected person's respiratory system. It may be possible to catch the virus before symptoms show, via close contact such as kissing or sharing eating utensils. However, in general people need to have some symptoms, such as a runny nose or cough, in order to be contagious. When your co-worker shows symptoms, he or she may indeed be spreading contagious droplets to your shared phone, to the doorknob of your office, or to the buttons on the fax machine. Your best defense is to wash your hands frequently.

Why does my child always seem to have a cold?

There are several reasons children catch colds so often. In day care and school they come in contact with lots of people, children and adults, who may be carrying a virus. Children don't always have good hygiene: They may wipe their noses with their hand instead of using a tissue, they may cough and forget to cover their mouth, or they may not wash their hands unless reminded. Also, adults have had longer to develop immunities to certain viruses. Children develop immunities to viruses only as they come in contact with them.

posted by occhiblu at 2:54 PM on February 16, 2005

And for the flu, the CDC says, "Adults may be able to infect others 1 day before getting symptoms and up to 7 days after getting sick. So it is possible to give someone the flu before you know you're sick as well as while you are sick."
posted by occhiblu at 3:00 PM on February 16, 2005

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