Individuals infected with H1N1 swine flu (also known as Mexican flu) appear to shed the virus and remain contagious for about twice as long as those with seasonal influenza.
Presented at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco in September, an initial study found that one in five swine flu patients still carried live virus particles for at least eight days after symptoms began.
A second study reported that 80% of patients continued shedding virus particles after five days of illness, 10% up to ten days, and in one case, particles persisted for twelve days after symptom onset—even after Tamiflu treatment.
Importantly, the second study did not confirm whether the detected virus particles were still viable. Modern detection methods are highly sensitive and can identify viral remnants long after infectivity has ended.
