SAN FRANCISCO, Sept. 14, 2009
H1N1 Spreads Long after Fever Stops
Virus Contagious Much Longer than Experts Had Previously Thought, New Studies Show
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(CBS)
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In-Depth Six Stages of Sickness How the World Health Organization rates pandemics
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Interactive Q&A: Swine Flu And Travel Precautions and advice for those worried about traveling
The federal Centers for Disease Control and Prevention has been telling people to stay home from work and school and avoid contact with others until a day after their fever breaks. The new research suggests they may need to be careful for longer - especially at home where the risk of spreading the germ is highest.
Swine flu also appears to be contagious longer than ordinary seasonal flu, several experts said.
"This study shows you're not contagious for a day or two. You're probably contagious for about a week," said Gaston De Serres, a scientist at the Institute of Public Health in Quebec.
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He presented one of the studies Monday at an American Society for Microbiology conference. It is the first big meeting of infectious disease experts since last spring's emergence of swine flu, which now accounts for nearly all of the flu cases in the United States. More than 1 million Americans have been infected and nearly 600 have died from it, the CDC estimates.
It is unclear whether the new research will lead the CDC to rethink its advice on how long people with swine flu should hole up. Long breaks from school and work do not seem worth it for a virus that now seems to cause mostly mild illness, said the CDC's flu chief, Nancy Cox. Swine flu is spreading so widely now that confining the sick does less good, she said.
"We tried to have our guidance balance out all of these factors," she said. "It's just virtually impossible not to have virus introduced into settings such as schools and universities."
Doctors know that people can spread ordinary seasonal flu for a couple of days before and after symptoms start by studying virus that patients shed in mucus. The first such studies of swine flu are just coming out now, and they imply a longer contagious period for the novel bug.
"It's probably realistic that this virus sheds much longer than seasonal flu," said Dr. Jonathan McCullers, an infectious diseases specialist at St. Jude Children's Research Hospital in Memphis, Tenn.
Three reports suggest this is so. De Serres and other researchers in Canada took nose and throat swabs from 43 patients with lab-confirmed flu and dozens of other sick family members.
On the eighth day after symptoms first appeared, 19 to 75 percent showed signs of virus remaining in their noses, depending on the type of test used.
"This proportion appears to be very big, and it is," but it's not clear how much virus is needed to actually spread flu, so the lower number is more reliable, he said.
Dr. David C. Lye reported on 70 patients treated at Tan Tock Seng Hospital in Singapore. Using a very sensitive test to detect virus in the nose or throat, he found that 80 percent had it five days after symptoms began, and 40 percent seven days after. Some still harbored virus as long as 16 days later. How soon they started on antiviral medicines such as Tamiflu made a difference in how much virus was found, but not whether virus was present at all.
A third report came from Dr. Guillermo Ruiz-Palacios of the National Institutes of Medical Science and Nutrition in Mexico, where the first cases of swine flu were detected.
Infected people "shed the virus for a very, very long time," often for more than a week after the start of symptoms, he told the conference. This was especially true of obese people, and patients who started on medicines longer than two days after symptoms first appeared.
The new reports suggest a longer contagious period for swine flu, but how long is not clear, Cox said. Even with it in your nose, "you might not be shedding enough virus to infect other people," she said.
That is why signs like coughing may matter more, De Serres said.
"Contagiousness varies, not only with the presence of the virus, but the other symptoms that would make you transmit," he said.
Swine flu symptoms can include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue, and sometimes diarrhea and vomiting. Young children may be cranky, less playful or not eat as much as normal, the CDC advises.
The agency's advice to stay home for a day after fever breaks does not apply to health care settings. There, confinement for seven days from the start of symptoms - or until they go away, whichever is longer - is still advised.
People who have had swine flu should cover their mouths when they cough or sneeze and wash their hands a lot once they do return to work and school, the CDC says.
© MMIX The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.
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- off all local testing showed that of all individuals had tested positive for influenza A -- 99% of those were also testing positive for H1N1
H1N1 is a 1st cousin to the ''spanish influenza'' that is the worry....remember that one, and the billions that died?
yes, modern medicine is better, but note: there is no cure for that either.
this is why peoples born before 1950 are not at risk, because of all the exposure they had from the spanish flu, and it's subsideries.
and yes........grandma should certainly cover her mouth!
my mom is the same way- drives me nuts!
ps, my daughter had tested + for both the flu and h1n1..3 daycare kids still came, and wallah--- NO one got either one. but, 1 month later, and 2 of the kids were around their ''grandma'' who tested positive....no handwashing, no covering of mouth, AND-- both kids are horribly ill.
wash people, wash.......cover, wash= better health all around! - Reply to this comment
- 1. As some European countries were taking H1N1 off their lists of worrisome diseases in JULY 2009, the CDC told United States Doctors to STOP TESTING FOR H1N1 altogether and to simply "assume all flu-like symptoms are H1N1". Because they felt that the testing was "a waste of resources" - could it be because no one was testing positive?
2. The CDC's own site (and their infectious disease specialists) claims that less than 20% of all flu-like symptoms are actually caused by an influenza strain and that "less than 1%" of THOSE are probable H1N1.
3. The CDC is pushing everyone to get the H1N1 shot... wait for it... even if they've already been diagnosed with actual, "possible" or "probable" H1N1! Money talks.
4. CBS learned that 4 out of 6 H1N1 panel members of the CDC have financial ties to the H1N1 vaccine makers. Meaning that they're crying epidemic because they'll rake in money from the vaccine selling.
5. the fact that #4 is illegal is moot since the CDC is legally allowed to issue waivers to those who ask for it - regardless of their financial ties or position at the CDC!
6. The ONLY death from Swine Flu in the 70s (which is when the 1st pandemic was called) was a Ft Dix soldier who was in an infirmary sick bed, was pulled from that sick bed and placed on a forced march until he collapsed and then shortly thereafter died. THE ONLY CONFIRMED CASE OF "SWINE FLU DEATH". The other 4 soldiers at Ft Dix recovered with no issues & no ill effects.
And those are just the ones I can remember off the top of my head from CBS's 3 months research for their exposé. Makes me mad. - Reply to this comment
- I knew it.....and now maybe my Mom will believe me. I told her that as long as she's coughing she could be spreading germs so she has to be 100% sure to always cover her mouth no matter what. She thinks that since she stays mainly in her own room that it's ok if she doesn't cover her mouth. However, her grand kids go in her room and are apt to touch something she has coughed on such as her computer mouse or keyboard. Not covering your mouth when you cough is my biggest pet peeve and when I see someone in public coughing without covering their mouth I always say something. Why is it so hard to COVER your mouth????? When my kids were little and just learning to cover their mouth when they coughed I had reflexes of lightening and would instantly cover their mouths with my hand so I know other parents can do the same thing!!
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- "blah, blah, blah", by BarryObamaSoetoro September 14, 2009 11:35 PM EDT
Watch out, B.O.S. The Illuminati will be coming to take you away! - Reply to this comment
- My fellow Americans make sure you get your swine flu shot as it is your patriotic duty to prevent this pandemic and your IBM Verichip RFID implant as this will keep you safe from terrorists. In addition this chip will speed up checkpoints, grocery checkout and financial transactions. This also allows medical professionals instant access to medical records in the case of an accident or medical situation.
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