Medical experts urge action after H7N9 virus shows resistance to Tamiflu
Signs are emerging that a mutation of the bird flu virus isn’t responding to antiviral treatment
Medical experts have called for a swift investigation into the possibility that a mutation of the H7N9 bird flu virus in China was becoming resistant to a drug commonly used to treat infected people.
Two patients in Guangdong province with the new and more virulent strain of the virus have shown signs of failing to respond to Tamiflu, the Nanfang Daily reported this week, citing Zhong Nanshan, an expert in respiratory diseases.
Virologists said the finding did not mean the drug was ineffective against bird flu but the situation should be examined.
There have been more than 1,200 laboratory confirmed cases of human infection of bird flu on the mainland since the emergence of H7N9 in 2013. As of Sunday, the death toll this year was 94, already surpassing last year’s 73 fatalities.
The World Health Organisation said on Wednesday it noticed virus mutations were spreading but the risk of the transmission among people remained low.
In about 7 per cent of human infections, scientists have identified genetic changes suggesting resistance to Tamiflu, the recommended treatment for the disease and the drug that is being stockpiled worldwide in preparation for a flu pandemic. The resistance was found in two patients with the mutation, the Nanfang Daily reported. The new strain was identified by the China Centre for Disease Control and Prevention.
Taiwan’s Centres for Disease Control announced earlier last month that gene sequence analysis of one H7N9 patient, who fell ill after visiting Guangdong, revealed the virus had a mutation that was resistant to antivirals such as Tamiflu and Relenza. The 69-year-old businessman died this week.
Zhong was quoted in the Nanfang Daily as saying most patients on the mainland were responding to Tamiflu, suggesting the mutated strain was not the dominant one or that “a considerable amount of viruses” had mutated.
He Jianfeng, the top infectious diseases expert at the Guangdong Provincial Centre for Disease Control and Prevention, told the newspaper both patients with the new strain had taken Tamiflu before. It was not clear if the resistance was caused by previous use of the treatment or the mutation.
Professor Malik Peiris, a virologist at the University of Hong Kong said Tamiflu resistance occurred occasionally in patients treated with the drug before.
He published a paper in the medical journal The Lancet four years ago saying patients in Shanghai had previously shown antiviral resistance. His further work showed the patients could be treated with other antivirals.
Peiris called for a quick investigation into the latest mutation.
“We need more information on how widespread this resistance is in recent viruses, especially those with the high pathogenic mutation,” he said.
Additional reporting by the Associated Press