The Department of Health´s Public Health Laboratory Services Branch (PHLSB) today (September 3) 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 sixth 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 three-year-old boy who developed flu-like symptoms since August 16. He sought medical advice from a general practitioner on August 16 and 20.

The patient was admitted to Queen Mary Hospital on August 20. His clinical diagnosis was pneumonia. He has already recovered and was discharged on August 22.

His nasopharyngeal aspirate specimen tested positive for HSI.

Further test results today showed that the virus was resistant to Tamiflu.

No Tamiflu had been prescribed to the boy by the general practitioner nor during hospitalisation.

The spokesman said there was no evidence of further transmission of Tamiflu-resistant HSI from the patient.

The PHLSB conducts routine sensitivity tests on specimens taken from confirmed HSI patients.

"So far more than 6,200 HSI samples have been tested for antiviral sensitivity in Hong Kong," the spokesman said.

The case will be reported to the World Health Organisation (WHO), he said.

Hong Kong has 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.

Ends/Friday, September 3, 2010