Doctors in Denmark have recorded the first case where swine flu has proven resistant to the leading antiviral drug used to protect the public from the infection.
Dr Carolyn Bridges, of the US Centers for Disease Control and Prevention (CDC), said the strain is thought to have developed in a patient who was taking the Tamiflu drug to prevent illness, and it has not spread to others. The patient later recovered.
There would be cause for greater concern if the patient had not been taking Tamiflu and had instead picked up a drug-resistant strain already spreading through the public, according to Dr Bridges.
Swiss pharmaceutical giant Roche, the makers of Tamiflu, also said it was not a mutation that included pieces of both seasonal flu and the new pandemic form of the virus.
There have been fears the new swine flu might exchange genes with seasonal or other types of flu and perhaps mutate into a more dangerous or more infectious form.
The drugs Tamiflu and Relenza are the best available defense against the swine flu virus until an effective vaccine is developed.
However, the situation in Denmark is isolated and Tamiflu continues to be recommended by the CDC and the World Health Organisation as a suitable treatment.
Copyright Press Association 2009