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The Department of Health's Public Health Laboratory Services Branch (PHLSB) today (February 9) detected a strain of human swine influenza (HSI) virus which was resistant to oseltamivir (Tamiflu).
A department spokesman said the virus was identified during PHLSB's routine sensitivity tests of the HSI virus to oseltamivir and zanamivir.
"This is the eighth case of Tamiflu resistance to HSI virus detected in Hong Kong.
"Tests showed that this strain is sensitive to zanamivir (Relenza)," he said.
The virus was isolated from the specimen taken from a 53-year-old woman who has underlying chronic disease and is on long-term immunosuppressive therapy. She developed flu-like symptoms since January 16. She was admitted to United Christian Hospital (UCH) on January 19 and her nasopharyngeal aspirate specimen taken on January 24 tested positive for HSI virus and was sensitive to Tamiflu. She was discharged on January 24 in stable condition.
The patient was readmitted to UCH on January 28 for shortness of breath. Test results today showed that the virus isolated from the patient's nasopharyngeal specimen on January 29 was resistant to Tamiflu but sensitive to Relenza.
The woman had been prescribed with Tamiflu during hospitalisation and it is likely that Tamiflu resistance emerged during the course of drug treatment.
The spokesman said there was no evidence of further transmission of Tamiflu-resistant HSI from the patient.
The case will be reported to the World Health Organisation (WHO).
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 6,500 HSI 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."
Ends/Wednesday, February 9, 2011
Issued at HKT 19:54
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