5 Nov 2009
The Department of Health's Public Health Laboratory Services Branch (PHLSB) today (November 5) 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 HSI virus to oseltamivir and zanamivir.
"This is the fifth time Tamiflu resistance in HSI virus found in Hong Kong and is the fourth local case."
"Tests showed that this strain is sensitive to zanamivir (Relenza)," he said.
The virus was isolated from the specimen taken from a 74-year-old man who developed flu-like symptoms on October 4. He was admitted to United Christian Hospital on October 7 for acute exacerbation of his chronic lung condition. He already recovered and was discharged from hospital on October 13.
His nasopharyngeal aspirate specimen was tested positive for HSI.
Further test results today showed that the virus was resistant to Tamiflu. The man had previous history of taking a full course of Tamiflu in late September during another admission for acute exacerbation of his chronic lung condition. His family member was asymptomatic.
The spokesman said there was no evidence of further transmission of Tamiflu-resistant HSI from the patient.
The PHLSB conducted routine sensitivity tests on specimens taken from confirmed HSI patients.
So far more than 5,500 HSI samples had been tested for anti-viral sensitivity in Hong Kong.
The case will be reported to the World Health Organisation (WHO), the spokesman said.
Hong Kong had an intensive surveillance system for antiviral resistant influenza viruses.
"We will closely liaise with the WHO and overseas health authorities to monitor the global development of antiviral-resistant HSI virus," he said.