Slight mutation worries experts

A slight mutation in the avian flu virus is worrying international influenza experts, but the World Health Organisation has not yet increased its pandemic alert level.

The WHO has confirmed that a virus taken from one of the first two people who died of avian influenza in Turkey shows mutations at the receptor-binding site.

The mutation took place on part of the hemagglutinin (H) of the virus, which is the protein on the virus' external coat that allows it to attach to a cell it intends to infect.

The world health body also pointed out that one of the mutations had been seen previously in viruses isolated from a small outbreak in Hong Kong in 2003 and from last year's outbreak in Vietnam.

However, it said, all available evidence indicates that no sustainable human to human transmission was taking place in any country experiencing human cases.

"Contact with infected birds is the principal source of infection," it said.

Guenael Rodier, the head of WHO's mission to Turkey, told Reuters that when a child got infected, the virus was being given more chance to adapt to human beings. "Giving it this chance could help create conditions for the emergence of a new virus," he said.

Contacted yesterday, consultant microbiologist Chris Barbara said such minor mutations to the virus were expected.

"It is well known that the influenza virus goes through minor mutations," he said, adding that as a member of the European Influenza Surveillance Scheme, Malta would be informed of any mutations.

Dr Barbara, the head of St Luke's Hospital's virology unit, said the minor mutations could enable the virus to attach to human cells. The more cases of bird flu there were, the bigger the risks of it changing.

However, he said there was no cause for alarm, with mutations taking place all the time. These mutations do not mean that a pandemic has started, he insisted, a comment that was reiterated by National Influenza Pandemic Standing Committee chairman Tanya Melillo.

Dr Melillo said that so far the evidence showed that people were contracting the virus straight from poultry. When contacted, she pointed out that the WHO, which is avidly monitoring the situation, had not raised its pandemic alert from level three.

She stressed that until now not enough data had been made available to the experts, but hopefully they would be able to carry out more biological studies in Turkey. She said it was important to determine whether family members of infected people and healthcare workers were becoming infected with the virus but were not showing symptoms.

"Hopefully the experts will have a better idea about the virus and the way it is spreading," she said.

Dr Melillo said it was well known that the virus would either change suddenly or over a period of time through gradual mutations. A lot of small mutations over a period of time could lead to a significant change. She said every human case could mean a greater risk for the virus to change into one that is transmitted easily from person to person.

Amid fears about the spread and mutation of the H5N1 virus, the tests on the Turkish victims have shown that the virus was sensitive to treatment by antiviral drugs. The Guardian yesterday quoted Hugh Pennington, of Aberdeen University, saying that the best method is administering amantadine and oseltamivir (Tamiflu) at the same time.

Australia's The Daily Telegraph said the virus, taken from the two teenage siblings who died earlier this month in eastern Turkey, responded to treatment by Tamiflu.

Meanwhile, the local Food and Veterinary Regulation Division said yesterday that according to a European Commission decision on Wednesday, Malta should suspend imports of poultry and poultry products from specific regions of Croatia - the counties of Viroviticko-Podravska and Osjecko-Baranjska.

"This measure has been taken in view of the fact that Croatia has notified the Commission of the suspicion of highly pathogenic avian influenza in that part of its territory, following the isolation of H5N1 virus collected from a clinical case in a wild species," it said.