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University of California, Berkeley
Center for Infectious Disease Preparedness
1918 University Avenue, 4th floor
Berkeley, CA 94704
E-mail: redi-us @ berkeley.edu
Phone: 510.643.4921
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How Are Colds and Flu Transmitted?
by
fluu
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last modified
2008-01-16 18:17
- Viruses
that cause colds and flu affect your respiratory tract: your lungs,
nose and throat. These viruses are transmitted through your respiratory
tract secretions, like saliva, and are also transmitted to others when
you cough and sneeze.
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- Viruses that cause respiratory diseases can be transmitted to other people in various ways. Transmission can occur through direct contact with respiratory secretions, such as shaking hands with someone who has covered their mouth with their hands; indirect contact, such as touching something that an ill person previously touched (e.g., a doorknob); and through the air in what are known as “large droplets.”
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- Most
of the viruses that cause colds and flu are thought to be transmitted
in “large droplets” of moisture that are expelled from the mouth when
someone coughs or sneezes. Thanks to gravity, these large droplets
carrying infectious viruses usually fall to the ground within three
feet of the person who coughed or sneezed. This is the basis for the “three-foot rule”
which recommends that you stay at least three feet away from someone
who is sick.
- Viruses
that cause colds and flu can live outside the body for longer than you
might think. Influenza viruses can remain infectious when
on metal surfaces for up to 48 hours and rhinoviruses can remain infectious on inanimate surfaces for up to 7 days!
For this reason, if someone who is sick with a virus causing a
respiratory disease (like a cold or the flu) coughs into their hand
then touches a doorknob, that virus can remain viable (infectious) on
that doorknob for quite some time. Anyone who touches that doorknob
while the virus is still infectious could pick up the virus and
potentially get sick if the virus enters their respiratory tract.
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Most
viruses that cause colds and flu can be transmitted from one person to
another for a few days, even up to a week, while that person is
sick. In the case of influenza, the flu virus can be spread from the
infected person to other people beginning the day before the infected person begins to have symptoms and even knows they are sick!
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REDI-US Study Information:
Cold & Flu Information:
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