New Lethal Flu Virus
By Patricia Reaney
LONDON (Reuter) - Scientists are keeping a close eye on a new influenza virus found in Hong Kong which is similar to strains that killed more than 22 million people this century.
The death of a three-year-old boy in Hong Kong in May is an isolated case, so far. But health organizations around the world have been alerted because the potential of the new virus for causing a pandemic, or global epidemic, in humans is unknown.
``I do not think it is a serious threat, not at this moment,'' Albert Osterhaus of the National Influenza Center of the Netherlands, said in an interview. ``But these viruses have, in principle, potential to be pandemic viruses.''
More than 20 million people died in the world's worst global flu epidemic -- the Spanish flu of 1918. Nearly 40 years later one million succumbed to the Asian flu and in 1967 the Hong Kong flu claimed 700,000 lives.
Scientists do not know what causes a flu pandemic. They believe the new strain originates in birds or pigs and then crosses over to humans who have no immunity against it.
Advances in technology have allowed them to identify new lethal viruses in humans and to launch global warning systems and immunization programs.
Many virologists believe another pandemic is already overdue.
Osterhaus and his colleagues examined the virus that was isolated from the respiratory tract of the boy who died in May. They confirmed that it was a new virus that had not been seen in humans before.
In a letter published in the scientific journal Nature Wednesday, he explained that the viruses responsible for earlier pandemics involved strains from birds that carried a combination of two viral envelope glycoproteins, haemagglutinin (H) and neuramidase (N).
The H1N1, H2N2 and H3N2 combinations caused the previous three major epidemics.
The new virus which virologists identified as H5N1 has a similar combination, and doctors believe the child may have caught it while visiting a chicken farm a week before he became ill.
Experts from the World Health Organization are investigating a similar virus that has killed chickens in Hong Kong to determine if the boy's case was a direct spillover and if there are other people infected with it.
``The contribution of the influenza A H5N1 virus infection to his death is not yet clear. But the virus identification is important as the first documented isolation of an influenza A virus of this subtype in humans,'' said Osterhaus.
So far no other cases how been reported and doctors do not know why the child caught it.
``We have seen in the past similar viruses spilling over from other animal species, including birds and pigs, and these events have led to pandemic spread of such viruses, but at this moment we do not know why the virus is not spreading among people.''
Osterhaus said early news of the new flu strain proved that the international influenza surveillance network set up by the World Health Organization was working. He also emphasized the importance of closely monitoring this and similar viruses in the future.

Immune System
Defenseless Against
New Hong Kong Flu

Highly Unusual Infection Direct from
Poultry, Bypassing Other Mammals

MEMPHIS, Tenn., October 9, 1997
-- A new influenza virus, first found in a now-deceased Hong Kong boy in May and against which the human immune system is defenseless, passed directly and most unusually from poultry to the boy, reported Robert G. Webster, Ph.D., chairman of the St. Jude Children's Research Hospital Department of Virology and Molecular Biology, and other scientists in an article published today by Nature.
"Typically, new influenza viruses pass through and are genetically modified in other mammals, like pigs, before reaching humans. A unique feature of this new virus of the H5 subtype found in Hong Kong, which we call HK97, is that it managed to cross the avian-human species barrier without prior adaptation in another mammalian species," said Dr. Webster.
Previously, only influenza viruses of the H1, H2 or currently circulating H3 subtypes havebeen shown to cause influenza in humans. It is not known how the HongKong boy was infected with the H5 virus. There was an avian flu epidemic a month earlier.
"Fortunately, there are no indications that more infections with HK97 have taken place in humans or that the virus has spread amongst humans, so HK97 does not seem to be a direct pandemic, or world epidemic, threat at present. However, its emergence illustrates the necessity for global influenza surveillance," said Dr. Webster.
According to a U.S. Department of Agriculture report, more than 460 blood samples were taken from people exposed to the boy and another 1,900 samples were taken from people showing flu symptoms, with none revealing new cases of HK97.
The Center for Disease Control (CDC) in Atlanta is developing a lab test for detecting the new virus, and the CDC Advisory Committee on Immunization Practices is scheduled to discuss HK97 when it meets on October 22-23.
Note: Dr. Robert Webster will be available to answer questions from the media on October 8, 1997, 2:30 pm to 3:30 pm, CDT, via teleconference at 800.289.0730. The conference will be replayed for interested listeners beginning 5:30 pm, CDT, October 8, 1997, and continuing for one week until October 15, 1997, by calling 888.566.0825.
St. Jude Children's Research Hospital, in Memphis, Tenn., was founded by the late entertainer Danny Thomas. The hospital is an internationally recognized biomedical research center dedicated to finding cures for catastrophic diseases of childhood. The hospital's work is primarily supported through funds raised by the American Lebanese Syrian Associated Charities (ALSAC). All St. Jude patients are treated regardless of their ability to pay. ALSAC covers all costs of treatment beyond those reimbursed by third party insurers, and total costs for families who have no insurance.

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