Prague, 27 July 2005 (RFE/RL) -- Russia’s chief epidemiologist, Gennadii Onishchenko, confirmed at a Moscow news conference on 25 July what had been suspected for several days: the first cases of bird flu ever recorded have now hit Russia.
"It is a fact that we have registered the H5 virus in our country. The virus affects birds and to date, there have been no human infections. To date -- at 7 a.m. I spoke with Novosibirsk -- the situation has not changed. No new cases among birds have been registered in the past two days thanks to measures we have taken. And our medical observations show that there have been no human cases," Onishchenko said.
The outbreak was initially detected last week in the western Siberian region of Novosibirsk.
So far, over 1,000 domestic fowl have died -- mostly ducks and geese. No human infections have been recorded.
Onishchenko said scientists believe this is because the bird flu strain detected in Russia is different, and weaker, than the one that has hit large parts of Asia. Most importantly, according to Onishchenko, there have been no cases of this variety ever infecting human beings.
Scientists believe that the bird flu virus, once it enters the human body, could mutate or mix with a human flu virus, creating an entirely new flu strain that could be easily passed between people.
The deadly Asian bird flu virus is known to scientists as H5N1. The Siberian variant has been categorized as H5N2, as Onishchenko stressed.
"To date, in all the available [scientific] literature, and in our medical community, there was never been a case of H5N2 being passed to humans," Onishchenko said.
Bird flu viruses are carried by wild, migratory birds. When the birds come into contact with domestic fowl or other animals, the virus can spread.
The Siberian outbreak is thought to have originated in Asia, like its deadlier cousin H5N1.
Despite Onishchenko’s reassurances, scientists around the world are concerned about the Russian outbreak and say it has the potential -- like other bird flu viruses -- to spark a deadly pandemic that could kill millions of people.
Albert Osterhaus, of the Erasmus Medical Center in Rotterdam, is one of the world’s top virologists. He explained how scientists categorize the family of viruses collectively known as “bird flu.”
"I think it's important to realize that all these viruses, in principle, come from wild birds and the 'H' and the 'N' that we mention relate to proteins on the surface of these influenza viruses in wild birds. And so far we have found 16 'H' molecules in different viruses and we have found 9 'N' molecules in different viruses. They come in different combinations, so you have H1N1, H2N3 etc," Osterhaus said.
That adds up to 144 permutations, or 144 varieties of bird flu. Eight years ago, the first cases of bird flu in humans were detected in Hong Kong. The strain was H5N1.
Of the 18 people who became infected in that first human outbreak, six died. The death toll was so high because humans have no natural immunity to H5N1 -- or any other strain of bird flu -- because until 1997, the disease never affected humans.
H5N1 remains the most-watched strain in Asia and it remains extremely deadly to the people who contract it.
So far, some 100 people have become infected and half of them have died. But Osterhaus notes that other strains of bird flu have also entered the human population and there is no reason why H5N2 -- the strain now active in Siberia -- could not do the same.
"We have now seen, since '97, that there are these viruses that can cross the species barrier, meaning they can also get into humans and they can cause disease and even death in humans. So, we know now that for instance the H7N7 in the Netherlands here caused one fatal case in humans," Osterhaus said. "We know now that the H5N1 virus in southeast Asia has caused more than 100 cases in humans, of whom more than 50 have died in the meantime. And now we see in Russia that another virus, another combination -- the H5N2 -- is causing problems there. And so far, we have not seen that these H5N2 viruses can cause disease in humans but I think it's far too early to say that this could not happen."
What is the link between human cases of bird flu and a possible flu pandemic? Scientists believe that the bird flu virus, once it enters the human body, could mutate or mix with a human flu virus, creating an entirely new flu strain that could be easily passed between people.
If that happened, the new virus would spread like wildfire -- as happened during three flu pandemics in the 20th century -- since no one would have any natural immunity.
To minimize the risk of this happening, Doctor Osterhaus recommends close monitoring of domestic animals in areas where bird flu outbreaks are detected. People should be monitored closely as well, so that they can be isolated and treated if they become infected.
"What you can do is first of all monitor the situation, both in wild and domestic birds. That's one thing. And try at least in the domestic birds to keep it under control. That's one thing. The other thing you can do, of course, is monitor in humans, at a very early stage, whether these things are happening," Osterhaus said. "And if it happens, although at this moment we don't have a vaccine yet and it will take time before we can develop one, you can take measures in the area where this might start. I think there are possibilities there. And I think the world community, in principle, should think about that."
At present there is no way of predicting which of the bird flu viruses could mutate or when this could occur.