Drug Resistance Identified in Avian Flu

Resistance to oseltamivir (Tamiflu) has been identified for the first time in patients with novel avian H7N9 influenza, according to a study conducted at Shanghai Medical College of Fudan University in China. 

Researchers followed 14 patients with A/H7N9 disease admitted to Shanghai Public Health Clinical Centre in April of 2013.  All 14 patients were treated with antivirals (oseltamivir or permamivir). 

In 11 of the 14 patients, antiviral treatment lead to reduction of the viral load in throat swab specimens.  Viral load in the remaining 3 patients was persistently high, despite treatment, leading to dependence on extracorporeal membrane oxygenation  and the deaths of 2 patients.

A mutation in the virus known to be associated with antiviral resistance was discovered in 2 of the patients, both of which were also treated with corticosteroids.  The mutation appeared to develop in at least 1 of the patients as a result of treatment. 

“The apparent ease with which antiviral resistance emerges in A/H7N9 viruses is concerning; it needs to be closely monitored and considered in future pandemic response plans,” they concluded. 

–Michael Potts

Reference

Hu Y, Lu S, Song Z, Wang W, Hao P, Li J, et al.  Association between adverse clinical outcome in human disease caused by novel influenza A H7N9 virus and sustained viral shedding and emergence of antiviral resistance [published online ahead of print May 28, 2013]. Lancet. http://dx.doi.org/10.1016/S0140-6736(13)61125-3