Skip to content

Detection of human swine influenza virus resistant to Tamiflu

Detection of human swine influenza virus resistant to Tamiflu
A spokesman for the Department of Health (DH) said the department's Public Health Laboratory Services Branch (PHLSB) today (September 9) detected a strain of human swine influenza (HSI) virus which was resistant to oseltamivir (Tamiflu).

The virus was identified during PHLSB's sensitivity test of HSI virus to oseltamivir and zanamivir, the spokesman said.

"The is the third time Tamiflu resistance in HSI virus found in Hong Kong and this is the second local case.

"Tests showed that this strain is sensitive to zanamivir (Relenza)," he said.

The virus was isolated from the specimen taken from a 38-year-old man who had no history of taking Tamiflu.

The patient developed flu-like symptoms on July 26 and his respiratory specimen taken at a Designated Flu Clinic was tested positive to HSI on July 30.

Investigation revealed that four other family members also suffered from laboratory confirmed HSI including his wife, son, and two younger brothers sequentially at end of July. One of his younger brothers, aged 32, who had onset of flu like symptoms on July 23 had received a full course of Tamiflu treatment.

Except for this patient, all available isolates from other members of the family, including the specimen taken from the younger brother before he received Tamiflu treatment, were tested to be sensitive to Tamiflu.

The patient and all other affected members had mild illnesses and recovered.

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

The spokesman said that PHLSB conducted routine sensitivity tests on specimens taken from confirmed HSI patients.

So far more than 3000 HSI samples had been tested for sensitivity in Hong Kong.

The case will be reported to the World Health Organization (WHO), the spokesman said.

He reiterated that Hong Kong had an intensive influenza surveillance system on antiviral resistant influenza viruses.

"We will closely liaise with WHO and overseas health authorities and monitor the global development of antiviral resistant HSI virus," he said.

Ends/Wednesday, September 9, 2009