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The Department of Health's Public Health Laboratory Services Branch (PHLSB) today (March 2) detected the 13th case of resistance to oseltamivir (Tamiflu) in a strain of human swine influenza (HSI) virus in Hong Kong.
A department spokesman said the virus was identified during PHLSB's routine sensitivity tests of the HSI virus to oseltamivir and zanamivir.
"Tests showed that this strain is sensitive to zanamivir (Relenza)," he said.
The virus was isolated from the specimen taken from a 58-year-old woman who had developed flu-like symptoms since February 6. She was admitted to Prince of Wales Hospital on the same day and her nasopharyngeal specimens taken on February 6, 8 and 9 tested positive for Influenza A virus subtype H1N1 (i.e. human swine influenza) and were sensitive to Tamiflu.
Further test results today showed that the virus isolated from the patient's nasopharyngeal aspirate on February 11 was resistant to Tamiflu but sensitive to Relenza. She had been prescribed with Tamiflu during hospitalisation and it is likely that Tamiflu resistance emerged during the course of drug treatment.
The patient has been transferred to Shatin Hospital in stable condition.
There was no evidence of further transmission of Tamiflu-resistant HSI from the patient.
The case will be reported to the World Health Organization.
The spokesman said that Hong Kong has an intensive surveillance system for antiviral-resistant influenza viruses. The PHLSB conducts routine sensitivity tests on specimens taken from confirmed HSI patients.
"So far more than 7,000 HSI virus samples have been tested for antiviral sensitivity in Hong Kong," he said.
"We will closely liaise with the WHO and overseas health authorities to monitor the global development of antiviral-resistant HSI virus."
From March 3, any cases of Tamiflu resistance that are detected will be reported in the Centre for Health Protection's weekly report, "Flu Express", which monitors and summarises the latest local and global influenza activities. The report is available at the Centre's website (www.chp.gov.hk).
Ends/Wednesday, March 2, 2011
Issued at HKT 18:25
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