Two new studies raise public health concerns about increasing antiviral resistance among certain influenza viruses, their ability to spread, and a lack of alternative antiviral treatment options. The findings are published in the January 1 issue of The Journal of Infectious Diseases. (Please see below for links to these articles online.)
Influenza viruses are treated with two classes of drugs: M2 blockers (adamantanes) and neuraminidase inhibitors (NAIs), including oseltamivir and zanamivir. While the spread of influenza strains with resistance to one class of drugs has been well documented in recent years, a new report from Larisa Gubareva, MD, PhD and colleagues at the Centers for Disease Control and Prevention (CDC) and at health agencies in West Virginia, Texas, and Canada, confirms that dual resistance can emerge in several ways and has been on the rise during the past three years.
The study analyzed 28 seasonal H1N1 viruses with dual resistance from 2008 to 2010 from five countries, revealing that additional antiviral resistance could rapidly develop in a previously single-resistant strain as a result of mutation, drug response, or gene exchange with another virus.
Although dual resistant viruses are still rare, the investigators noted an increase in the number of tested viruses with this resistance, from 0.06 percent (2007-2008) to 1.5 percent (2008-2009) to 28 percent (2009-2010); however, during the 2009-2010 season the number of circulating seasonal H1N1 viruses was low, and only 25 viruses were tested. "Because only two classes of antiviral agents are approved, the detection of viruses with resistance to drugs in both classes is concerning," said Dr. Gubareva. "If circulation of viruses with dual resistance becomes more widespread among any of the predominant circulating influenza A viruses, treatment options will be extremely limited. New antiviral agents and strategies for antiviral therapy are likely to be ne
|Contact: John Heys|
Infectious Diseases Society of America