A virulently fatal form of H5N1 bird flu has not
yet appeared in humans. But "flu season" runs from fall through early winter in the northern
hemisphere - so this is the time when new mutations are most likely to appear. Scientists are afraid that H5N1 bird flu will infect someone already
sick with another virus, cross-breed inside the host, and mutate into a form that is easily transmitted human-to-human. A virulent strain will most
likely occur if H5N1 cross-breeds with another flu strain. Authorities are on high alert.
Scientists know that diseases use human bodies as mixing vessels - microbes cross-breed and mutate when a victim has more than one disease. This is
why virulent new diseases tend to appear in over-crowded places without adequate medical care. It's a matter of opportunity.
H5N1 bird flu is a 'new' mutation, different from seasonal flu - as was the 1918 bird flu. Seasonal flu tends to kill only the very young and very
old. But unlike seasonal flu, and like the 1918 bird flu, H5N1 is most deadly in young people roughly between 7 and 40 years of age.
The US government just released a report explaining one way this can happen. In an animal study, scientists infected a group of mice with a mild
virus: the virus killed 0% of the younger mice, and 14% of the older mice. The researchers then extracted the virus from the older infected survivors,
and used it to infect a new group. They found that in its new form (after cycling through a host), the virus killed 43% of younger mice and 71% of
The originally mild virus, or "low pathogenic" form, gained
virulence after passing through the host(s), to become a "high pathogenic"
Discovering What Makes Flu Viruses Lethal
In an animal study, none of a group of younger adult mice infected with a mild strain of a common virus died, but 14 percent of older infected mice
did. The scientists then isolated and studied the mild virus from the infected older mice.
The mild viral strain did not affect young adult mice in previous tests, but the scientists found that after it had cycled through an older mouse
host, it killed 43 percent of other younger mice later infected and 71 percent of other older mice later infected.
The scientists do not know how the viral strain mutated to mimic its virulent cousin in the older mouse hosts, but concluded that because of the
world’s increasingly older population, the potential impact of age-associated viral evolution on public health warrants further investigation.
NOTE: A bird flu is considered "high path" only
if it kills 76% to 100% of chickens infected artificially (ie., 7 or 8 out of 8 infected).
And FYI: Low-pathogenic H5N1 has been confirmed in the United States this year
- including in Michigan, Pennsylvania and Maryland.
* In the USA, the Departments of Agriculture and Interior tests and reports on H5N1 bird flu only
in wild birds;
* The government does not require US poultry producers to test for H5N1 bird flu; and
* Testing food chickens for H5N1 bird flu is totally voluntary in the USA
A bit of an oversight considering how mutation works, dontcha think?
This is the first in a series of 9 new bird flu threads about Mutation; Water Safety; Food Safety; Symptoms; Diagnosis; Medical Treatments;
Traditional, Alternative, and Over-the-Counter Treatments; Molecular Pathology; and Spread.