Bird flu can mutate to infect humans
31/03/2008 16:02

MOSCOW. (RIA Novosti interview with Professor Dmitry Lvov) - The international medical community has met in Bali for the Sixth International Bird Flu Summit to discuss the possibility of mutations in the avian flu virus leading to human pandemics.

Attending the summit was Dmitry Lvov, director of the Ivanovsky Research Institute of Virology at the Russian Academy of Medical Sciences.

The danger of mutations, Lvov warns, is considerable, and the situation is potentially highly alarming.

"The H5N1 virus needs only one or two amino acid changes to become transmittable between humans, to produce mutations and hybrid cells," Lvov said. "Nobody knows when these killers may appear, for everything depends on the specific features of the virus's receptors. So far, it can provoke pathologies after reaching the lower parts of the respiratory tract. The ordinary flu virus hits the upper sectors."

The scientist said: "Since H5N1 mutations never stop, the virus could eventually 'learn' to hit the upper parts of humans' respiratory tract. This would be very bad, but in the worst scenario bird and flu viruses will infect the same recipient, for example a pig, whose organism is susceptible to both viruses. There is one chance in a million of that, but this one chance could result in a global catastrophe that would claim millions of lives."

"The scale of danger is huge. Any country will be completely defenseless against the disease, because quarantines will not help, as the Spanish Flu pandemic of 1918-1919 showed," Lvov said.

Question: The virus has not yet overcome the genetic barrier, yet humans are dying of bird flu, although mainly in East Asia. Why?

Answer: About 400 humans have contracted bird flu. So far, it is extremely difficult to contract bird flu, for molecular and genetic reasons. You must have direct contact with an infected bird to catch the disease, for example, by drinking the infected bird's blood (some nations do this) or "kissing" the infected hen. I was told that a girl started giving the kiss of life to her favorite hen, which she had nurtured since it was an egg. As a result, the child died.

In other words, hygiene has now become a matter of life and death. So far, there have not been any cases of virus transmission between humans.

Q: Bird flu has existed since prehistoric times. What has provoked the appearance of its current, highly virulent form?

A: Birds are the natural carriers of bird flu. The virus and birds have lived together for 300 million years, so that wild fowl have become immune to it. But when conditions change, the bird flu genome changes too, producing new, highly virulent strains. To keep living, viruses must mutate. Sometimes new and dangerous strains infect humans, spreading across the globe incredibly fast.

Scientists reported 40 years ago that birds carry all the pandemic flu strains, although not all scientists accepted that view immediately. The first proponents of this theory were Robert Webster, of St Jude's Children's Research Hospital, Memphis, Tennessee; Professor Graeme Laver of Australia; and myself. We were ridiculed then. Unfortunately, we have now been proved right.

Q: You also predicted the threat of a panzootic, an outbreak of an infectious disease of animals that spreads across a large region (for example a continent), or even worldwide.

A: My institute warned of the danger of a panzootic in September 2003, three months before the first cases were reported. I said in my report at the international flu congress in Japan that Russian scientists had isolated the low pathogenic H5 flu virus in wild fowl in the Altai region (southwest Siberia) and the southern regions of the Maritime Territory in Russia's Far East. We also predicted that the virus might hit the poultry farms of Southeast Asian countries, and that it might quickly become highly pathogenic. Unfortunately, our forecast was later confirmed.

Q: Epidemics can be fought with the help of vaccines. Do we have them for bird flu?

A: Creating a vaccine is a fundamental project, which our institute is involved in. Russia has a program of poultry vaccination and is producing eight times more vaccine than it needs. It can export the rest.

We don't have, and cannot have, a human vaccine, because we don't know which pandemic strain will hit humans. Bird flu is adjusted to its carrier, the bird. We are studying bird flu areas and relations between the virus and birds, other animals and humans in different ecosystems.

In the event of a pandemic, we'll need two or three months to create the human vaccine. This is the fastest a civilized country can launch its large-scale production.

Q: How is the H5N1 virus behaving now? Has the risk of dangerous mutations increased?

A: The virus is changing, and not in the direction we had hoped for. It is becoming more virulent, although this is nonsense theoretically. Nobody can change the evolution of the flu virus or prevent a pandemic now. The worst thing is that H5N1 has reached wild fowl, which migrate between their winter and summer areas and infect poultry in the process.

Russia felt the impact of this in 2005, when the virus reached the country from Lake Kukunor in Qinghai, China. Later that Qinghai-Siberian cocktail went on to spread throughout the world.

The most important information is that when the highly virulent H5N1 flu virus reaches a natural bio-community, it does not eventually peter out. It continues to circulate there, and retains its high pathogenic potential.


Original article: RIA Novosti
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