Swine flu resistance to medicines increasing
21 June 2011
Increasingly resistant variants of swine flu are being detected in Australia, indicating a possible new threat from the virus, which has been stable since the 2009 pandemic, experts say.
The WHO Collaborating Centre for Reference and Research on Influenza in Melbourne found among 28 strains of influenza A (H1N1) 2009 virus sampled around Darwin, 30 per cent had the mutation S247N. This gives mild resistance to the antiviral medicines oseltamivir (Tamiflu) and zanamivir (Relenza).
Another sample, from an immunocompromised patient who died in Perth in March, had S247N plus another mutation, H275Y, a combination that was 6000 times more resistant than the 2009 strain.
"When you get the two mutations together, like the guy in Perth had, then it has a profound effect," commented Dr Heath Kelly, from the Victorian Infectious Diseases Reference Laboratory.
"It has been a very stable virus with almost no resistance reported - that's why this paper has attracted so much attention."
Continued mutations could lead to clinically significant reductions in the efficacy of medicines, the study authors said.
Last Reviewed: 22 June 2011
- 1. Hurt A, Lee R, Leang S, et al. Increased detection in Australia and Singapore of a novel influenza A(H1N1)2009 variant with reduced oseltamivir and zanamivir sensitivity due to a S247N neuraminidase mutation. Euro Surveill 2011; 16: 19884. http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19884 (accessed Jun 2011).
