How Long Are Germs Infectious Outside The Human Body?
MINNEAPOLIS (WCCO) -- The flu was striking hard at schools last week. Sixty schools reported outbreaks, according to the MN Department of Health. That's compared to 14 the week before.
Third-grade teacher Emily Torgerson wrote to Good Question wanting to know: "Do I have to wash my clothes every day after school? ... My friends think it's silly, but I do it because I want to stay healthy. The problem is I have a lot of laundry."
How long are germs infectious outside the body? Good Question.
"Flu viruses are pretty wimpy," Dana Davis, a microbiologist at the University of Minnesota, said. "They don't survive very long."
Flu viruses will remain infectious on hard surfaces, like tables or doorknobs for up to 24 hours. On soft or porous surfaces like cardboard or clothes, it lasts two to three hours. That's because those surfaces allow liquid to seep into them and these viruses don't do well in dry conditions.
"[The virus] dries out a lot faster because the water gets pulled through the surface," Davis said.
On skin, the flu virus can last just 10 to 20 minutes.
"There are a lot of microbes on there already that can compete with the virus and break it down," he said.
That doesn't mean you shouldn't wash your hands often. That's because it's the hands to the face that can make a person sick.
"If it gets on your hand, it's not necessarily going to infect you, you need to bring it to your eyes or nose or mouth," he said. "People touch their face all the time."
It's harder to determine a timeline for colds because there are so many different viruses that can cause colds.
As to Mrs. Torgerson's original question, Davis recommended more hand soap over laundry detergent.
"It depends on how long ago a student might have coughed on her," Davis said. "I don't know if she has to wash her clothes so often, but she should wash her hands a lot."
