Re: California Dairy herds positive for the dairy virus

On 9/18/2024 11:11 AM, *Hemidactylus* wrote:

RonO <rokimoto557@gmail.com> wrote:

On 9/17/2024 1:18 PM, x wrote:

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[snip]

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Ok.  Sorry to have implied that about a joke.
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What is going on with the flu strains with a 50% fatality rate?

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There is an Asian and European H5N1 strain of avian influenza that has
been responsible for over 800 human deaths (50% mortality of known
infected humans).  Infection is not a common occurrence and requires
contact with infected birds.  Wild bird migration brought this virus to
North America, but the virus that infected the Dairy cattle was a
recombinant with another North American avian influenza strain.  It
inherited the H5 and N1 antigen genes from the Asian virus, but around
half of it's genome comes from another influenza virus.  This is likely
why it doesn't have a 50% mortality when it infects humans.  So far
humans have only exhibited mild symptoms, but the worry is that the
virus will mutate to better infect humans and become more pathogenic.
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Is that something involving low numbers of infected and statistics
or is that something real about the nature of those flu strains?

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As noted above the Asian H5N1 has infected fewer than 2,000 people in
Asia and Europe, but over 800 of them died due to the infection.
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Does that involve differences in antigen presentation?

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Due to the recombinant half, the dairy virus is antigenically different
than the Asian H5N1, but initially the H5 antigen was neutralized by
related H5 virus that the CDC had already banked for vaccine use.  One
thing that they are not making a big deal about is that the latest human
case (without known animal contact) in Missouri has a couple of amino
acid substitutions relative to the original dairy H5 and the Missouri H5
can avoid the existing H5 antibodies, and those antibodies are now 10 to
100 times less effective in neutralizing an infection.  This just means
that they have to start working up a vaccine strain with the new H5
mutations.
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Do they have symptoms similar to other flu but more severe
or can they have vastly different symptom sets in comparison
with other colds or flus?
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Most of the humans infected with the dairy virus have mild symptoms with
most of them having only itchy eyes.  The virus was not isolated from
nasal swabs so the infection had not become respiratory.  Virus has been
isolated from eye swabs of infected individuals.  The latest Missouri
example is different.  Apparently the virus was detected in samples
taken normally to check for respiratory infections, but the patient was
not exhibiting the normal respiratory symptoms.  Instead the patient had
"nausea, vomiting, diarrhea and weakness".  The CDC has noted that these
are not the normal respiratory symptoms of influenza, but they do not
note that these are symptoms that have been associated with the H5N1
Asian virus with a high human mortality.  The CDC seems to have the goal
of downplaying how bad things probably are.
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So the common misnomer of “stomach flu” applied to norovirus would actually
apply in cases where influenza infection actually does result in digestive
symptoms?

Yes, influenza virus can be associated with "stomach flu" symptoms, and as I noted the H5N1 avian influenza virus that has a high mortality in humans has produced these symptoms.
https://my.clevelandclinic.org/health/diseases/22401-bird-flu
Until the Missouri case the dairy H5N1 had not been associated with those symptoms, but they have occurred in the high mortality cases of humans infected by the Asian strain of H5N1.

 So if someone says “I have stomach flu” I would now reply “I sure hope
you’re wrongly calling noro that, because actual H5 stomach flu is much
worse!”
 

The Asian H5N1 has a 50% mortality in humans.  As I have noted the Dairy H5N1 is a recombinant and around half of it's genome comes from another avian influenza virus.  The Dairy H5N1 had only been associated with mild symptoms until the Missouri case, and the CDC is trying to claim that the Missouri patients symptoms were due to something else other than the dairy virus.  They are probably wrong because another person (close contact of the hospitalized patient) exhibited the same symptoms but was never tested.
Ron Okimoto