Resistant swine flu found
The first case of Tamiflu-resistant swine flu developing in someone given the drug prophylacticly has been reported by Canadian doctors.
Tamiflu was given to all family members of a young boy who had developed swine flu. But a day later his father developed flu-like symptoms and he tested positive for H1N1.
His virus had a single amino acid change (H275Y mutation) of its neuraminidase protein.
The resistant strain of the virus was 400 times less sensitive to the neuraminidase inhibitor than the wild type virus, according to doctors in Quebec writing in the New England Journal of Medicine. It remained sensitive to zanamivir (Relenza).
The researchers believe resistance developed because the patient had sub-therapeutic blood levels of Tamiflu at the time of being infected – allowing the virus to mutate.
Study leader Dr Mariana Baz, an infectious disease physician at the University Hospital of Quebec, said there was a need to ‘limit the indications for post-exposure prophylaxis'.H1N1 virus H1N1 virus