Singapore: Doctors and researchers at the Shanghai Public Health Clinical Center, China, have made a worrying revelation that the new virus strain, which recently killed 36 people in China, has developed resistance to antiviral drugs like Tamiflu. Antiviral drugs like Tamiflu act as neuraminidase inhibitors and are the only known way of treating H7N9 so far. These drugs do not cure the virus but reduce the severity of the illness and speeden up the recovery process.

Also read:
Bird flu spreads easily between ferrets, humans may be next

Having treated about 14 H7N9 cases with the Tamiflu drug, doctors found that the virus showed resistance to the drug in three of the cases. Even though no new cases of H7N9 have come to light since May 8, Chinese researchers are closely monitoring these developments to come up with future pandemic response plans.

The researchers further found traces of H7N9 in patient's urine, blood and stools, indicating that the virus is not just spread through respiratory secretions.

H7N9 avian influenza, which struck five Chinese cities in March 2013, has so far killed 36 people and has infected 131 people. The World Health Organization (WHO) continues to maintian that the virus is easily transmissible between humans.

One of the researchers at the center has revealed that, "While the drug reduced levels of the virus in 11 of the patients, genetic testing of bird flu in the three, who did not respond to treatment, showed it was able to effectively mutate to resist Tamiflu. In fact in one of the patients we believe that resistance was a direct result of the presence of Tamiflu. The apparent ease with which antiviral resistance emerges in H7N9 viruses is concerning, it needs to be closely monitored and considered in future pandemic response plans."