Tamiflu-Resistant Swine Flu Virus Found in Hong Kong
By Nipa Piboontanasawat and Jason Gale
July 3 (Bloomberg) -- Tamiflu-resistant swine flu was found in a teenager who hadn’t taken Roche Holding AG’s best-selling antiviral medicine, Hong Kong’s health department said.
The city’s Public Health Laboratory Services Branch identified the drug-evading variant during routine surveillance of flu specimens, the department said in a statement today.
This marks the first known case of Tamiflu resistance in a swine flu patient not treated with the drug, which has been stockpiled by governments worldwide to fight pandemic influenza. The specimen was collected from a 16-year-old girl who flew from San Francisco and was intercepted by officials at Hong Kong International Airport on June 11, according to the statement.
“Picking it up in a patient who was not treated is a cause for concern,” Malik Peiris, professor of microbiology at Hong Kong University, said in an interview. “One case doesn’t change the world, but if we are seeing more and more cases in patients who are not treated, then I think it would be more serious.”
The patient, who was admitted to Queen Mary Hospital for isolation, tested positive for the new H1N1 flu strain and opted not to take Tamiflu, Hong Kong’s health department said. She had mild symptoms and was discharged upon recovery on June 18.
Denmark, Japan
Basel, Switzerland-based Roche said on June 29 that a swine flu patient treated with Tamiflu in Denmark showed resistance to the drug for the first time. Japan’s health ministry reported a case of resistance yesterday in a woman from Osaka who had taken a 10-day course.
Studies have shown that Tamiflu-resistant bugs develop in 0.4 percent to 4 percent of adults and children treated for seasonal influenza, Claudia Schmitt, a spokeswoman at Roche, said by phone from Basel today.
It’s likely the few reported cases of drug-resistant swine flu emerged independently, Hong Kong University’s Peiris said.
“The key point is whether the strains will become dominant and then we will have a problem,” he said. “At this moment, I don’t think there is cause for alarm. There is certainly cause for heightened surveillance.”
The new H1N1 pandemic virus and a seasonal H1N1 variant are more likely to develop resistance to Tamiflu than other common flu strains, Peiris said. About 95 percent of the H1N1 seasonal flu viruses circulating around the world evade the Roche pill, according to a March 21 World Health Organizationreport.
Glaxo’s Relenza
No widespread resistance to GlaxoSmithKline Plc’s flu drug Relenza has been reported in seasonal flu, and there have been no reports of resistance in swine flu.
“Constant, random mutation is the survival mechanism of the microbial world,” WHO Director-General Margaret Chan said in an address to a meeting on the flu pandemic in Cancun, Mexico, yesterday. “Like all influenza viruses, H1N1 has the advantage of surprise on its side.”
Tamiflu and Relenza, an inhaled powder, reduce the severity and the duration of flu symptoms by 24 to 30 hours if treatment is started within the first two days of illness, according to the companies.
Both drugs work by blocking a protein on the surface of influenza particles called neuraminidase, which allows the virus to spread from infected cells to other cells in the body.
Scientists say mutant H1N1 viruses have evolved to evade Tamiflu through a single mutation in the neuraminidase that prevents the medicine from clinging to the viral protein, enabling the pathogen to spread.
The case in Hong Kong indicates that the mutant virus is capable of being transmitted among people, said Jennifer McKimm- Breschkin, a virologist at the Commonwealth Science and Industrial Research Organization in Melbourne.
“It’s very disturbing that, fresh into the human population, this one appears now to be able to retain fitness despite having the mutation and to be able to spread,” she said in a telephone interview today.
To contact the reporters on this story: Nipa Piboontanasawat in Hong Kong at [email protected]; To contact the reporters on this story: Jason Gale in Singapore at [email protected].
Last Updated: July 3, 2009 07:46 EDT
By Nipa Piboontanasawat and Jason Gale
July 3 (Bloomberg) -- Tamiflu-resistant swine flu was found in a teenager who hadn’t taken Roche Holding AG’s best-selling antiviral medicine, Hong Kong’s health department said.
The city’s Public Health Laboratory Services Branch identified the drug-evading variant during routine surveillance of flu specimens, the department said in a statement today.
This marks the first known case of Tamiflu resistance in a swine flu patient not treated with the drug, which has been stockpiled by governments worldwide to fight pandemic influenza. The specimen was collected from a 16-year-old girl who flew from San Francisco and was intercepted by officials at Hong Kong International Airport on June 11, according to the statement.
“Picking it up in a patient who was not treated is a cause for concern,” Malik Peiris, professor of microbiology at Hong Kong University, said in an interview. “One case doesn’t change the world, but if we are seeing more and more cases in patients who are not treated, then I think it would be more serious.”
The patient, who was admitted to Queen Mary Hospital for isolation, tested positive for the new H1N1 flu strain and opted not to take Tamiflu, Hong Kong’s health department said. She had mild symptoms and was discharged upon recovery on June 18.
Denmark, Japan
Basel, Switzerland-based Roche said on June 29 that a swine flu patient treated with Tamiflu in Denmark showed resistance to the drug for the first time. Japan’s health ministry reported a case of resistance yesterday in a woman from Osaka who had taken a 10-day course.
Studies have shown that Tamiflu-resistant bugs develop in 0.4 percent to 4 percent of adults and children treated for seasonal influenza, Claudia Schmitt, a spokeswoman at Roche, said by phone from Basel today.
It’s likely the few reported cases of drug-resistant swine flu emerged independently, Hong Kong University’s Peiris said.
“The key point is whether the strains will become dominant and then we will have a problem,” he said. “At this moment, I don’t think there is cause for alarm. There is certainly cause for heightened surveillance.”
The new H1N1 pandemic virus and a seasonal H1N1 variant are more likely to develop resistance to Tamiflu than other common flu strains, Peiris said. About 95 percent of the H1N1 seasonal flu viruses circulating around the world evade the Roche pill, according to a March 21 World Health Organizationreport.
Glaxo’s Relenza
No widespread resistance to GlaxoSmithKline Plc’s flu drug Relenza has been reported in seasonal flu, and there have been no reports of resistance in swine flu.
“Constant, random mutation is the survival mechanism of the microbial world,” WHO Director-General Margaret Chan said in an address to a meeting on the flu pandemic in Cancun, Mexico, yesterday. “Like all influenza viruses, H1N1 has the advantage of surprise on its side.”
Tamiflu and Relenza, an inhaled powder, reduce the severity and the duration of flu symptoms by 24 to 30 hours if treatment is started within the first two days of illness, according to the companies.
Both drugs work by blocking a protein on the surface of influenza particles called neuraminidase, which allows the virus to spread from infected cells to other cells in the body.
Scientists say mutant H1N1 viruses have evolved to evade Tamiflu through a single mutation in the neuraminidase that prevents the medicine from clinging to the viral protein, enabling the pathogen to spread.
The case in Hong Kong indicates that the mutant virus is capable of being transmitted among people, said Jennifer McKimm- Breschkin, a virologist at the Commonwealth Science and Industrial Research Organization in Melbourne.
“It’s very disturbing that, fresh into the human population, this one appears now to be able to retain fitness despite having the mutation and to be able to spread,” she said in a telephone interview today.
To contact the reporters on this story: Nipa Piboontanasawat in Hong Kong at [email protected]; To contact the reporters on this story: Jason Gale in Singapore at [email protected].
Last Updated: July 3, 2009 07:46 EDT
