Two people who died of bird flu in Egypt last month had a strain of the H5N1 virus which has shown “moderate” resistance to the frontline antiviral Tamiflu, the World Health Organization (WHO) said on Thursday.
Known as “294S”, the mutated strain was first detected in 2005 in a teenage girl in Vietnam who survived, but this is the first evidence of it spreading beyond Asia, it said.
The United Nations agency said the latest cases did not change its recommendation to treat bird flu patients with Tamiflu, known generically as oseltamivir. Made by Swiss-based Roche, the flu drug is being stockpiled by governments worldwide for use in the event of an influenza pandemic.
“What we’ve confirmed is that H5N1 viruses isolated from two patients in recent cases in Egypt both showed this so-called 294S change,” Keiji Fukuda, coordinator for the WHO’s global influenza program, told Reuters.
In a statement confirming the mutation, the WHO said the public health implications of the findings were “limited”.
“At this time, there is no indication that oseltamivir resistance is widespread in Egypt or elsewhere,” it said.
“WHO is not making any changes in antiviral treatment recommendations for H5N1-infected persons ... because the clinical level of resistance of these mutations is not yet well established. Current laboratory testing suggests that the level of reduced susceptibility is moderate,” it added.
Mutated strain
The mutated strain was found in a 26-year-old Egyptian factory worker and his teenage niece in the Nile Delta province of Gharbia, both of whom died in December along with another female relative, according to Fukuda.
The uncle and niece, who lived in the same house, were given Tamiflu in the second hospital in which they were treated, after the disease was already more developed, he said.
Egypt, which announced on Wednesday it was treating another bird flu patient, has recorded 10 deaths among 19 confirmed human cases — the largest toll outside Asia.
Worldwide, there have been 161 fatalities among 267 known cases since 2003, according to the Geneva-based WHO.
The WHO reaffirmed last May that patients should get Tamiflu as a frontline treatment, but said in certain cases, doctors may consider using it along with amantadine, an older class of effective flu drugs.
Its recommendations, based on a consensus of international experts, also said that zanamivir -- marketed as Relenza by GlaxoSmithKline — was a second choice.
Both Tamiflu and Relenza belong to a new drug class called neuraminidase inhibitors and can prevent the virus from infecting cells in the first place.
