South China Morning Post, March 1, 2017. Experts said signs of resistance in a new strain of the deadly H7N9 bird flu virus against a drug used to treat people with the infection needs swift investigation to clarify how to handle the mutation.
Two patients in Guangdong province with a new and more virulent strain of the virus have shown signs of failing to respond to the drug Tamiflu, the Nanfang Daily reported this week, citing Zhong Nanhsan, an expert in respiratory diseases.
Virologists said the finding did not mean the drug was ineffective against bird flu, but a swift investigation was needed to assess how to handle the situation. There have been over 1,200 laboratory confirmed cases of human infection for bird flu in mainland China since the first was reported in 2013.
As of Sunday, 94 people have died from the illness on the mainland this year. The number of deaths so far this year have already surpassed the total number of H7N9 fatalities last year, which was 73.
Mutation of H7N9 bird flu strain found in Guangdong patients
The drug resistance was found in two patients found to have the mutation of the virus, the report said. The new strain was identified by the China Centre for Disease Control.
Taiwan’s Centre for Disease Control announced earlier this month that gene sequence analysis of a H7N9 bird flu patient, who fell ill after visiting Guangdong, found the virus had a mutation that was resistant to antiviral drugs such as Tamiflu and Relenza. The patient, a 69-year-old businessman, died earlier this week.
Zhong was quoted in the Nanfang Daily as saying most patients on the mainland were responding to Tamiflu treatment, suggesting the mutated strain of H7N9 was not the dominant virus, or “a considerable amount of viruses” did not mutate.
He Jianfeng, chief expert in infectious diseases at the Guangdong Provincial Centre for Disease Control and Prevention, told the newspaper both patients with the new strain had taken Tamiflu before and it was not clear whether the drug resistance was caused by previous use of the treatment or the virus mutation.
Professor Malik Peiris, a virologist at the University of Hong Kong who published a paper in the medical journal The Lancet four years ago saying H7N9 patients in Shanghai had previously shown antiviral resistance, said Tamiflu resistance occurred occasionally in bird flu patients treated with the drug before.
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His further work showed these patients can be treated with alternative antiviral drugs. Professor Peiris called for a quick investigation into the latest H7N9 virus mutation.
“We need more information on how widespread this resistance is in recent viruses, especially those with the high pathogenic mutation,” he said.
Tamiflu can still be useful for treatment and early use of the drug will reduce the chance of resistance developing and increase the chance of a cure, he added. Patients who have begun antiviral treatment need to be monitored to see whether there was a good response and to change to alternative drugs if there was no improvement, he said.