People With Swine Flu May Be Contagious Longer Than Thought

New studies suggest transmission of virus may last up to a week

HealthDay + More

By Steven Reinberg
HealthDay Reporter

TUESDAY, Sept. 15 (HealthDay News) -- People infected with swine flu seem to be contagious longer than patients with ordinary seasonal flu, several new studies suggest.

But it's not clear what impact the findings will have on health-care experts' recommendations to combat the H1N1 swine flu, since the virus continues to produce relatively mild infections in most people and recovery time is fairly fast, just like seasonal flu, the Associated Press reported.

"This study shows you're not contagious for a day or two" with H1N1 swine flu. "You're probably contagious for about a week," said Gaston De Serres, a scientist at the Institute of Public Health in Quebec, Canada, who presented one of the studies Monday at an American Society for Microbiology conference in San Francisco.

Levels of virus present in nasal mucus can give experts an indication of whether the flu can still be spread by coughing and sneezing. In the Canadian study, between 19 percent to 75 percent of people with H1N1 flu still showed signs of virus in their noses eight days after the first onset of symptoms. Two others studies -- one from Singapore, the other from Mexico -- produced similar results.

The meeting is the first major gathering of infectious-disease experts since swine flu first emerged last spring in Mexico and the United States, before circulating around much of the globe. The World Health Organization is currently reporting nearly 280,000 cases of infection, with at least 3,205 deaths worldwide.

In the United States, H1N1 swine flu now accounts for an estimated 98 percent of the flu virus in circulation, with more than 1 million cases of infection and an estimated 600 deaths. By way of comparison, regular seasonal flu hospitalizes more than 200,000 American each year and causes an estimated 36,000 deaths, according to the U.S. Centers for Disease Control and Prevention.

The CDC has been recommending that people infected with swine flu stay home and avoid contact with others for at least one day after they've been free of fever without the use of fever-reducing medications.

Nancy Cox, director of the CDC's Influenza Division, told the AP that keeping people out of work or school for extended periods of time may not be worth it, since the H1N1 virus continues to cause mostly mild illness, primarily in children and young adults.

"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."

Also on Monday, U.S. health officials urged small businesses to prepare now to keep their shops running if the flu season turns severe. The guidelines for small businesses are one of several guidelines issued by federal officials in recent weeks. Others included guidelines for schools, day-care centers, health-care workers and large businesses.

"We need to make sure that operations and businesses continue on even as we go through the flu season," Janet Napolitano, U.S. Secretary of Homeland Security, said during a Monday afternoon news conference.

Dr. Daniel Jernigan, deputy director of the CDC's Influenza Division, advised businesses to prepare for two different scenarios -- first if the H1N1 flu remains as mild as it has so far, and second if the virus should change and illness becomes more severe.

"Another key step for small businesses is to protect your workforce," Jernigan said. People should be encouraged to stay home if they are sick and not return to work until their fever has subsided for a day without using fever-reducing medication, he said.

"For most people that is three to five days away from work," Jernigan said. "Some small businesses will have to change their leave practices, but we think that's a good thing for this year."

According to the guidelines issued Monday, a small business plan should include the designation of a workplace coordinator responsible for H1N1 issues. The plan should also:

  • Encourage sick workers to stay at home without fear of reprisal.
  • Find ways for workers to work from home.
  • Promote personal hygiene, such as frequent handwashing.
  • Encourage workers to get a seasonal flu shot.
  • Encourage workers to get the H1N1 vaccine when it becomes available.
  • Provide workers with information on flu risk factors.

If an employee does become sick at work, the employee should be moved away from other workers to limit infection until the worker can go home, according to the plan.