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The Department of Health's Public Health Laboratory Services Branch (PHLSB) today (February 16) detected another case of resistance to oseltamivir (Tamiflu) in a strain of human swine influenza (HSI) virus.
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 10th 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 33-year-old man with chronic illness. He had presented with fever and cough since January 27. He sought medical attention at Queen Mary Hospital (QMH) on the same day and was prescribed with Tamiflu. The man was admitted to QMH for persistent fever on February 1. He was discharged on February 7 in stable condition.
His nasopharyngeal aspirate specimen taken on January 27 tested positive for influenza A virus subtype H1 (human swine influenza), which did not show resistance to Tamiflu. However, the virus in the specimen taken on February 3 was found to be resistant to Tamiflu but sensitive to Relenza. 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 6,800 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."
Ends/Wednesday, February 16, 2011
Issued at HKT 18:47
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