When the coughing stops is probably a better sign of when a swine flu patient is no longer contagious, experts said after seeing new research that suggests the virus can still spread many days after a fever goes away. 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. 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. 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.
