"Passage" through humans can increase the virulence of a new flu strain.

[Ladyhawk]

I'm not a scientist. I'm only going to repeat what I've read from the book by John M. Barry: The Great Influenza.

Many epidemiologists believe the 1918 flu virus (an H1N1 Influenza A virus like the one that just emerged) started in Haskell County, Kansas. It was so severe that the county doctor, Loring Miner, reported it even though influenza was not a reportable disease at the time. Epidemiologists believe that conscripted soldiers brought a milder form of the disease to a nearby cantonment.

The first "wave" of the flu was mild.

However, because flu viruses can mutate so quickly, the 1918 virus was able to mutate back to a more efficient form. As it passed through generations of humans, natural selection made it better at what it did. Of course, if a virus becomes too good at killing, it can burn out quickly. Ebola actually becomes less severe as it passes through humans and eventually, it simply fizzles out.

What concerns me are the parallels of this new virus to the emerging virus. Like the 1918 virus, it was more virulent when it first made the leap from animals to people. And, like the 1918 virus, it seems to have mutated to a less virulent form. The 1918 virus emerged in April. This virus emerged in March. In 1918, the first "mild" wave killed more people than a "normal" flu virus does, but it wasn't severe enough to warrant attention from authorities. Then in August and September, after passing through several generations of humans, the virus mutated back to a more lethal form. The second wave was devastating. The third, only a bit less so.

Even if the current virus is "mild," it still bears watching due to the ability of flu viruses to mutate quickly and the evolutionary effects of "passage" through human hosts.

FWIW, Ladyhawk

[xchrom]

1. the remnants of this virus will probably change as the year goes on.

whether it gets worse i don't know.

but it is most certainly a possiblity.

[Ladyhawk]

2. It could simply fizzle out, too.

:shrug:

There's really no way to predict what this virus will do.

[xchrom]

4. it could -- but i wouldn' bet on that. nt

[Ladyhawk]

8. No. I'm waiting to see what the virus does.

It's gonna do what it's gonna do.

[Liberal Veteran]

3. Or it could decrease the virulence of a new flu strain.

It surely bears watching, but it could go either way. If I understand it correctly, it depends on the type of environmental pressure it is under. It could mutate into something more virulent, but much milder. And the opposite is true as well.

[Ladyhawk]

6. Absolutely true.

From Mr. Barry's book: "But the phenomenon is complex. The increase in killing efficiency does not continue indefinitely. If a pathogen kills too efficiently, it will run out of hosts and destroy itself....Initially Ebola has extremely high mortality rates, but after it goes through several generations of human passages, it becomes far milder and not particularly threatening....So passage can also weaken a pathogen."

This wasn't the case with the 1918 strain of Influenza.

More: "Lethality lay within the genetic possibilities of this virus; this particular mutant swarm always had the potential to be more pestilential than other influenza viruses. Passage was sharpening its ferocity. As it smoldered in the roots, adapting itself, becoming increasingly efficient at reproducing itself in humans, passage was forging a killing inferno."

There's no way to know what this new virus will do.

[dos pelos]

23. Population density determines virulence

Consider this:in an environment of easy transmissibility,whether due to crowded conditions,behavior,or sanitation a virus whose strategy is to replicate as fast as possible at the expense of its' host will easily proliferate.In such an environment a virus which is slower to replicate,which is less harsh on its' host,is out competed by the faster,harsher virus.The environment selects which viral strategy will dominate.In an environment of low transmissibility,the faster,harsher virus will tend to perish in its host,which may also die.The virus which is slower,gentler on its host will proliferate in such an environment.Thus the environment determines virulence.I think basic public health strategies are designed to create environments of lower transmissibility,thus selecting for the less virulent forms of
a viral disease.The ease of transmission in a given environment determines virulence.Basic public health methods and good civil engineering are the most powerful defenses against viral pandemics and are the reason why crowded unsanitary Mexico City has these deaths and the US does not.

[Ladyhawk]

26. The 1918 virus had a tinderbox due to the first World War.

It was able to truly explode in the cantonments and close conditions in the trenches. That would seem to support what you wrote. By the way, where did you get this information? I'd be interested in learning more.

In the 1889 flu pandemic, the second wave was also more virulent than the first, possibly due to "passage." I can't think of any crowded conditions that would have caused this phenomenon.

I would love to see the Swine Flu get weaker and fizzle out, but there is a possibility that passage through human hosts could make it stronger. The author of The Great Influenza expressed concern that this might happen again, as it did in 1889 and 1918:

http://www.nytimes.com/2009/04/28/opinion/28barry.html

"In all four instances, the gap between the time the virus was first recognized and a second, more dangerous wave swelled was about six months. It will take a minimum of four months to produce vaccine in any volume, possibly longer, and much longer than that to produce enough vaccine to protect most Americans. The race has begun."

It's just something to think about.

[dflprincess]

5. Or the first wave could be mild and by the time a second or third wave shows up

the vaccine will be ready. - Something they didn't have in 1918.

[Ladyhawk]

7. Yes. And the progress of the virus might be slowed because authorities know

of its existence. Right now, it doesn't seem to be as infectious as some other influenza viruses. Of course, the genes that control transmissability could also be honed through passage.

It's anyone's guess as to what will happen. I'm hoping for a good outcome for everyone.

[Sigh Sister]

29. Vaccine development

is a guessing game. They try to predict how the virus will mutate and make a vaccine based on it. Hopefully, they will get it right.

[nadinbrzezinski]

9. Time will tell, but kudos for SOLID info

now take shelter some folks are virulently allergic to facts, no pun

:evilgrin:

[Ladyhawk]

12. Yes. This virus is no joke.

We can't know what this virus will do, but it isn't simply a smoke screen to hide the Republican Scandal du Jour. The emergence of a new flu virus is newsworthy. It shouldn't be on 24/7, but it should be regarded as a serious situation.

We can't know for sure what the virus will do, but 1918 is a stark warning that influenza can be deadly.

[nadinbrzezinski]

13. Well it hasn't been 24\7

been watching news all day on CNBC... and three programs have covered torture in depth

And the rest of the day, they went in and out

Not that you'd know that if you only read DU

:-)

The problem they have is that they are a 24 hour news channel, its own issues

And it is a moving target

[jwirr]

10. As usual I have been busy all day and want to know what is happening

with the flu story. I heard that some students came home from Cancun sick with the swine flu - some news program - is this true? How long is the incubation period for this flu? If you are in Mexico and are exposed how long before you know that it is safe? My daughter is in Cancun right now and we have 5 babies under 3 years old. I am really afraid of what she is bringing home with her.

[nadinbrzezinski]

14. Some answers

yes some folks have come back from all over, not just Cancun, and it has spread, best place to find out, CDC website

http://www.cdc.gov/swineflu/

As to incubation again from them, 24-48 hours

And if this helps, it is concentrating on the young, 20-44 age group

WHO

She will be questioned when they come to the country as to health status and be given a yellow information sheet

She should take that seriously and anybody develops even a cough, go to the doctor

ANTI VIRALS in the first 48 hours are the most effective

Hope this helps

[Ladyhawk]

16. Thanks. The article I read said the incubation period has been revised upward.

The initially virulent strain of the disease (like the 1918 virus) causes death in those with healthy immune systems by what is called a "cytokine storm." When the virus invades the lungs, the immune system throws everything at it, causing the victim to drown in his / her own fluids.

It's important not to use antivirals until a person is actually sick. Flu viruses mutate extremely rapidly and could develop resistance to antivirals within a very short time.

Thanks for good info, nadinbrzezinski.

[nadinbrzezinski]

17. Lady hawk thanks for making me look from Baylor school of medicine

Up to a week for showing symptoms that changed from last night...

http://www.khou.com/news/local/stories/khou090427_mh_swine-flu-reader-questions.118d57377.html

Oh and mods, I posted the whole thing since this is Q&A on public health


BAYLOR COLLEGE OF MEDICINE

Dr. Pedro Piadra with Baylor College of Medicine
Dr. Piedra’s research is focused on influenza and other respiratory illnesses in children. He is principal investigator of a study to protect the community against influenza through universal vaccination of school-aged children, who have the highest infection rates and play a major role in the transmission of the flu throughout the community. He has also worked to investigate candidate vaccines for the control of epidemic influenza.

Questions and Answers:

How do you catch swine flu?

Swine flu is spread by humans to other humans. When we cough, we release both large and small droplets into the air. Swine flu can be carried in these droplets.

How long after coming in contact with the virus does it take to develop symptoms?

Symptoms develop rapidly as swine flu has a short incubation period. The CDC says the incubation period could be up to a week, but symptoms may start showing up in as a few days after contacting the virus.

If someone with swine flu was handling produce sent to us from Mexico, can we get the virus?

No, not from produce sent up from Mexico as the virus cannot live that long. It’s more like catching a cold or a flu, which means that if someone in Houston has the virus and touches something – whether it’s produce or a phone – and you touch it immediately after, you may pick up the virus from there.

I'm seeing reports of some deaths. Is that going to be people who have weak immunities or will an otherwise healthy person be at risk of dying too?

SWINE FLU
Harris County phone bank: 713-212-0200

PDF: Swine flu FAQ

Q&A: Swine flu and you

CDC: Key swine flu facts

Interactive: Swine flu worldwide

Google Map: Swine flu cases

Anti-viral drugs and swine flu

Swine flu tips for travelers

Tips for airline passengers

CDC travel alert

Border Blog: Latest from Mexico

Slideshow: Swine flu outbreak

Informacion En Espanol

Get swine flu updates on Twitter

We do not know the risks yet. So far, what we have been seeing is that the virus has not caused the same problems in the U.S. as it has in Mexico. Predominately, older and people with weak immune symptoms could be the most at risk, but it may still cause problems in healthy individuals.

I have horses, and there are sometimes pigs in my neighborhood as Agricultural projects. Can my horses catch this and transmit it to us?

It is possible for the flu to be transmitted from humans to horses, but the major problem we are seeing now is the virus transferring from human to human. Humans can also pass the virus onto pigs and vice versa.

Would it be beneficial for me to get a pneumonia vaccine in case the flu hits the Houston area? I cannot take the flu vaccine or Tamaflu, due to allergies. I am 55.

If you are in the right age group or at risk, it is prudent to be vaccinated. If a seasonal flu shot is still available in your area, I recommend getting that. It won’t protect against swine flu, but we don’t know if it will help against this strain of the flu. There has been evidence in Mexico that people who had the flu shot seem to recover better, but more tests need to be done to prove this is really the case.

We have a trip booked to a resort in Cancun for July 4th. Should we cancel? Will it be reaching pandemic proportions by then? How likely is it that the US will close its borders?

There has been an outbreak of swine flu in Mexico already. If a pandemic is to occur, it most likely won’t happen until August or September. However, keep in mind that going to Cancun or anywhere in Mexico in July would be risky. You may want to avoid the country until the CDC gives the okay.

This goes for other vacation areas in Mexico such as the Cabo and Puerto Vallarta. The more you travel, the greater risk you have of meeting someone who has been in contact with the virus.

I would like to know how long does the virus live outside of the body? I understand that it has to be transmitted through mucous membranes but it you touch a surface and then touch your mucous membranes or another surface is the virus still alive or contagious?

Swine flu can live outside the body for approximately six to eight hours on a surface such as table or a phone. It doesn’t live as long on the skin.

To help prevent being infected, keep your hands clean and wash them often.

Are the elderly as likely to or more likely to become infected with swine flu as the younger population?

If swine flu becomes a pandemic, everyone is vulnerable. It will affect the very young, elderly and sick, but it could also affect young healthy adults like the Spanish flu did in 1918.

My two year old son has flu-like symptoms including fever, cough, congestion, and blisters in his mouth. He has not been exposed to anyone that has recently been to Mexico that I am aware of - should I be concerned? Do I need to take him to the pediatrician or just ride the virus out if his symptoms do not worsen?

You do not have to be exposed to someone who has been in Mexico to get swine flu. You can get it from what we call second, third or fourth germ spread such as from a doorknob or money. It also can be passed from person to person to person.

To be safe, take your son to the pediatrician to be checked out.

Can I get swine flu from eating bacon? What about pork chops or pork rinds? Really, if I eat anything from a pig, can I get the swine flu?

No. The virus is not spread by eating pork or pork products. You can still eat bacon.

I am sailing Carnival on Sunday with a port call to Cozumel. CCL just said they are not revising ports of call. I feel like I'm being held hostage on board, because the crew and other passengers will get off and bring this back on for me. How can I stay safe?

A cruise is the perfect place for an epidemic to occur. Even if you do not leave the ship in Mexico, if anyone is in contact with the virus, you run the chance of being exposed. Either consider not going or take the risk of exposure. Face masks won’t do much to help you, but do try to get a seasonal flu shot before you board if you do go.

Also Online
Map of where swine flu has been reported
Get up-to-date swine flu information on Twitter
Video Slideshows Blogs
What are the symptoms of the swine flu and has any cases been known in our area?

There are currently no reported cases in Houston. The symptoms are for swine flu are the same as seasonal flu. People who have it will generally have a fever, cough, congestion, sore throat, muscle aches and will feel tired/run down. Some people may experience vomiting and diarrhea.

People from everywhere eat at restaurants. Is this a place where the virus can be spread? Should we avoid places where large groups of people meet?

Right now, the risk in Houston is minimal as there have been no reported cases. If swine flu is introduced into the community, then it would be prudent to avoid places where large groups of people gather.

Do school students need to stay home?
At the moment, Houston children can continue to go to school. But if the virus spreads to Houston, the answer may change. Children are an excellent vehicle for transmitting viruses.

Are hospitals doing anything to protect patients at hospitals right now?

Yes, Houston hospitals are testing patients that show symptoms and isolating them from other patients.

Is Houston prepared for this?

The city is as prepared as any other major city. Physicians are being proactive to help prevent the spread of the virus if it does appear in the city. Samples are being processed at the CDC or by the state.

[Ladyhawk]

18. Thank you. That was very informative.

I live in California and my health isn't very good. Part of me wants to stay away from people entirely, but there's no way I could do this for several months until the new flu either fizzles out or hits hard (or something in-between).

I guess we're looking at August / September if there's an emergence of a virulent pandemic. That's close to the same thing seen in 1918.

All we can do is keep an eye on the situation and go about our lives.

[nadinbrzezinski]

19. Me personally staying away from crowds if I can

I also live in cali, on ground zero for cali

San Diego

And yes, my chances right now are next to nill, but I struck lightning yesterday

[jwirr]

21. our family will make sure she takes it seriously - thanks.

[Ladyhawk]

15. You'll need to double-check me on this.

"As for the incubation period, from the cases in the United States and even Mexico, the incubation period from the time of exposure to the onset of symptoms seems to be three to four days. They originally thought it was less, but have since determined it is three to four days."

http://www.msnbc.msn.com/id/30439999/

_____

The virus seems to be mutating to a milder form. According to John M. Barry, once a virus has jumped from one species to another, it can weaken. As it passes through the human population, it can adapt and become more virulent.

Could your daughter spend four days quarantined in a motel room? Influenza is usually highly infectious. Airborne virus is enough to infect another person.

Even if she does contract the new virus, there's every possibilty she'll get the milder form. That would put her in good shape if the virus mutates into a deadlier form. In 1918, those who became ill in the first wave had some resistance to the lethal second wave.

[Ladyhawk]

11. Here's what John M. Barry had to say today in his NY Times Op-Ed:

Where Will the Swine Flu Go Next?

John M. Barry (author of The Great Influenza)

AS the swine flu threatens to become the next pandemic, the biggest questions are whether its transmission from human to human will be sustained and, if so, how virulent it might become. But even if this virus were to peter out soon, there is a strong possibility it would only go underground, quietly continuing to infect some people while becoming better adapted to humans, and then explode around the world.

What happens next is chiefly up to the virus. But it is up to us to create a vaccine as quickly as possible.

Influenza viruses are unpredictable because they are able to mutate so rapidly. That capacity enables them to jump easily from species to species, infecting not only pigs and people but also horses, seals, cats, dogs, tigers and so on. An avian virus responsible for the 1918 pandemic jumped first from birds to humans, then from humans to swine (as well as other animals). Now, and not for the first time, pigs have given a virus back to humans.

Mutability makes even existing, well-known flu viruses unpredictable. A new virus, formed by a combination of several existing ones as this virus is, is even less predictable. After jumping to a new host, influenza can become more or less virulent — in fact, different offshoots could go in opposite directions — before a relatively stable new virus emerges.


more: http://www.nytimes.com/2009/04/28/opinion/28barry.html

[dflprincess]

20. One disheartening thing I heard about any possibility of a vaccine is that

flu vaccines are produced in Europe. Apparently the U.S. doesn't have much in the way of facilities for mass producing a vaccine.

Maybe we'll learn a lesson about not making anything here anymore.

[jwirr]

22. It is a matter of national security to be able to provide our own meds

but no one in government seems to see that.

[dflprincess]

24. It's a matter of national security to be able to make our own

steel so we can make our own planes and tanks. Or just to be able to make our own shoes and clothes.

[Ladyhawk]

25. Kicking. nt

[sfpcjock]

27. Now virus can be treated by Tamiflu

...assuming you have visited your doctor, are of a mind to get vaccinated and have done so early in the infection cycle so the Tamiflu is more effective.

What the woman, Laurie Garrett of the Council on Foreign Relations on Charlie Rose, Monday night was saying, I think, is that later the virus could mutate to favor Tamiflu-resistant strains if it sees a lot of exposure to the vaccine.

The virus may also be killed by the seasonal flu vaccine which contained another related H1N1 antigen.

Watch the 10 minute video: http://www.charlierose.com/view/clip/10265">Charlie Rose show, Monday

[Delphinus]

28. You know ...

reading this makes me see that these viruses are alive - not necessarily with collective intelligence but if it can mutate into something else, it's just doing what it needs to do to survive. Or am I looking at this in a weird way?