Madrid - A patient infected by a mutant strain of the swine flu A(H1N1) virus has died in Spain, the health ministry said Friday.
"We have registered three cases of mutation, including one which was fatal. These are three isolated cases, there has been no transmission to any other person," a ministry spokesman told AFP.
It is the sixth fatal case of mutated A(H1N1) virus in Europe, after one in the Netherlands and two each in France and Norway.
Last month the World Health Organisation said that mutations had been observed in Brazil, China, Japan, Mexico --, where the swine flu pandemic began -- Ukraine and the United States as early as April.
Italy also reported a non-fatal case on Monday.
"The mutations appear to occur sporadically and spontaneously. To date, no links between the small number of patients infected with the mutated virus have been found and the mutation does not appear to spread," a WHO statement said on November 20.
The WHO also underlined that there was no evidence of more infections or more deaths as a result, while the mutated virus detected up to that point remained sensitive to antiviral drugs used to treat severe flu, oseltamivir (Tamiflu) and zanamivir (Relenza).
Scientists fear that mutations in flu viruses could cause a more virulent and deadly pandemic flu. The global health watchdog reiterated a call for close monitoring.
One of the three patients infected in Spain had a mutation which made the virus resistant to Tamiflu but was successfully treated with another medication, the health ministry spokesman said.
The two other patients, including the one who died, were infected with another type of mutation which was identical to the one detected for the first time in November in Norway, he added.
The patient who survived with this mutation had a "light form" of the disease, he said.
Spain has so far recorded 169 deaths related to the swine flu virus, according to the latest toll issued by the health ministry. It was the first European country to confirm a case of the virus.