There still hasn't been much new happening with Bird Flu since 1969. A case or two of transmission from human to human means nothing until it approaches a level which can sustain an epidemic.
I was surprised to hear that these were the "first confirmed human to human transmission", because clearly remembered such transmission occurring during the SARS epidemic which at the time was assumed to be Bird Flu, but has since been discovered to be something entirely unrelated.
The 1918 outbreak was bad enough by itself that deaths Bird Flu over the past 100 years have occurred at a rate comparable to deaths from AIDS over the past 30 years. If a similar virus would get loose today, there would probably if anything more deaths, since there are many more people in the world today and today we haven't something similar to the epidemic of 1889-1890 which provided immunity to the 1918 flu. Actually, I'm a lot more worried about the reconstructed 1918 strain getting out than I am about a new strain developing. Releases of hoof and mouth disease from experimental laboratories show that lab containment procedures are far from perfect, and and the 1918 virus had genes which gave it a very high mortality rate. Like the Ebola virus, it killed directly without having to rely on pneumonia, looking to doctors of the time more like gas poisoning than pneumonia. From the previous link:
During the 1918 influenza pandemic, pathologists observed at autopsy severe destruction of lung tissue unlike that typically seen in cases of pneumonia.
Despite the danger, I'm getting rather tired of the incessant drumbeat that a Bird Flu pandemic is imminent. It is no more imminent than it has been for the past 35 years, and every year we have about a 1 in 75 chance of seeing a Bird Flu epidemic killing over 5 million people, though with a good chance of it being a lot more than 5 million. By the time the big epidemic finally comes, people will probably be so tired of the warnings that they won't listen to them anymore.
It's never been clear that Ebola wouldn't cause a major worldwide pandemic if let loose in a metropolitan area. In the relatively small number of outbreaks seen so far, it has always appeared in a remote area, infected most of the hosts in the village where it appeared, killed most of them, and then, having burnt out its source of available victims, burnt itself out before reaching a major metropolitan area. There was a single person infected in this latest outbreak who reached a major city, but apparently he didn't spread it to anyone.
Ebola is poorly transmitted by air, and usually requires touch for transmission. What has really limited its transmission, however, is simply that it is too virulent. It has a short incubation period, and is transmissible for only a short time before the victim (usually) dies. The new, less virulent strain, therefore, has a much higher chance of causing a major global pandemic than the other strains which have been seen before.
Quarantines result in relatively little drop in the total number of cases, but spread these over a longer amount of time. Nevertheless, based on the 1918 influenza epidemic, this tends to save a lot of lives, because epidemics tend to evolve towards causing less mortality the longer they last. Presumably, if it went on for the year or two it appears that it would take to vaccinate a significant fraction of the population, you could reduce the number of cases significantly as well.
There are always old diseases mutating to utilize a new host. West Nile virus has been in the U.S. only since 1999. It's mostly just luck that while it devastates bird populations, the impact on human health has been relatively minor. Malaria continues to evolve to ignore our treatment drugs. And there are always new diseases which we don't yet know anything about, like AIDS before 1981 or SARS before 2003. The next big plague is actually most likely to be something we haven't heard of yet.
In any case, if our health care system can't handle emergency care on a normal day, I see little chance of it coping with a major epidemic.
Bird flu this...Ebola that. When are we going to see a virus that turns humans into zombies?
It's the end of the world as we know it, and I feel fine
"...treatment opportunities are so much more advanced..."
So you are suggesting that modern medical science might be able to respond to an avian flu pandemic as fast as it has with AIDS?
January 20, 2009. Justice becomes possible.
Why is it that people panic about something like Bird Flu, West Nile, SARS, Ebola, etc, which are highly unlikely to kill them, while still engaging in activities (such as, you know, driving a car, handling a gun, using a ladder) that have very high (relatively speaking) fatality rates?
Ce n'est pas une pipe. C'est une signature.
9
 2
|
Re: Understandings of risk
Sun Dec 23, 2007 at 04:45:49 AM EST
5.00 (informative)
|
US annual chance of death, from your link:
Motor Vehicle Accidents - 1 in 6,535
Falls from ladders - 1 in 749,125
Bird Flu, chance of death in 1918 outbreak:
US: 1 in 120
World: 1 in 25 - 1 in 50
Assuming a 1 in 100 year recurrence interval, chance of death
US death rate : 1 in 12,000
World death rate: 1 in 2,500 -1 in 5,000
Recurrence interval required to make your chance of death from Bird Flu in the US equal to your chance of death from the "higher" probability, falling from ladders: 749,125/120 = once every 6,240 years. Are you seriously suggesting that we see Bird Flu epidemics less often than once every 6,240 years? Because that's what it sounds like to me.
If you take only years where SARS, Ebola, Bird Flu, etc. are not in global epidemic, the risk is of course very low, but those aren't the years we should worry about.
11
9
|
Re: Understandings of risk
Sun Dec 23, 2007 at 09:41:02 AM EST
|
My response is largely what TonedEff said, but also that it's not realistic to compare the 1918 death toll to today's death toll, because treatment possibilities are so much more advanced (and the world isn't just recovering from a world war). A much more realistic comparison would be the 1968-69 Hong Kong flu, which had a much lower death toll. Granted, the Hong Kong strain wasn't as deadly as the Spanish flu, but we're also quite a bit further along in med-tech than we were in the late 1960s...
Ce n'est pas une pipe. C'est une signature.
13
11
|
Re: Understandings of risk
Sun Dec 23, 2007 at 03:02:46 PM EST
5.00 (interesting)
|
If modern medicine is so good, why does it work so well with Ebloa?
Treatment is primarily supportive and includes minimizing invasive procedures, balancing electrolytes, replacing lost coagulation factors to help stop bleeding, maintaining oxygen and blood levels, and treating any complicating infections. Despite some initial anecdotal evidence, blood serum from Ebola survivors has been shown to be ineffective in treating the virus. Interferon is also thought to be ineffective. Ribavirin is ineffective. In monkeys, administration of an inhibitor of coagulation (rNAPc2) has shown some benefit, protecting 33% of infected animals from a usually 100% (for monkeys) lethal infection (unfortunately this inoculation does not work on humans). In early 2006, scientists at USAMRIID announced a 75% recovery rate after infecting four rhesus monkeys with Ebola virus and administering antisense drugs.
Regarding the
effectiveness of standard anti-viral agentsAfter following WHO protocols in treating 41 victims of the H5N1 bird flu virus (19% of the world-wide cases of bird flu reported to date), Nguyen Tuong Van, MD, who runs the intensive care unit of the Center for Tropical Diseases in Hanoi, Vietnam concluded that Tamiflu, the drug most widely stockpiled around the world to combat a potential bird flu pandemic, is "useless." According to this article, the WHO confirmed Van's experience stating that Tamiflu has not been "widely successful in human patients", but speculated the drug has not been administered until late in the disease in many Asian countries.
The standard recommended dose incompletely suppresses viral replication in at least some patients with H5N1 avian influenza, increasing the risk of viral resistance and rendering therapy less effective (de Jong et al. 2005). Accordingly, it has been suggested that higher doses and longer durations of therapy should be used for treatment of patients with the H5N1 virus (de Jong et al. 2005, Ward et al. 2005).
Clinical trials for an increased dosage were set to begin in by May 2007. All avian influenza cases in Indonesia, Thailand, and Vietnam will be inducted into the trial. The trial will also include 100 cases of severe seasonal influenza from each of those countries, plus the United States. Half of cases will receive the current standard dosage, and half will receive a double dosage, but for the standard length of time.[7][8]
Chokephaibulkit et al recommend the use of oseltamivir for children with avian influenza, based on experience with one patient.
Modern medicine is still quite good (
though getting worse) at dealing with bacteria, but it deals poorly with viruses. It can't cure herpes or AIDS. Regarding
viral pneumonia:There is no known efficacious treatment for pneumonia caused by SARS coronavirus, adenovirus, hantavirus, or parainfluenza virus; treatment is largely supportive.
Basically, you can give victims fluids, give them antibiotics to prevent secondary infections, give them oxygen to increase the amount of lung damage required before they die, give them some anti-virals that you know don't work and pray. This is, of course, assuming you have enough hospital beds, which we know we don't have.
Of course, the general health of people is generally better today, and the 1918 virus is thought to have spread especially quickly in troop barracks which aren't as common in the absence of a World War. But if general health was enough to save people from dying from it, why did so many (presumably healthy) people of middle age die from it? It didn't just take the weak, like other influenza outbreaks.
Sure, the 1918 virus was spread by troop movements, but what about greatly increased air travel, which would spread the virus around even faster today than in 1918?
In short, I really see no reason to believe we would fare any better today than we did then. We've just been lucky enough to not see a virus as bad as in 1918 recently.
10
9
|
Re: Understandings of risk
Sun Dec 23, 2007 at 07:30:28 AM EST
|
Sorry, but isn't comparing the Spanish influenza pandemic to avian flu just a little bit false? The Spanish flu was an airborne virus spread from human to human. At least thus far, the avian flu has only been transmitted from birds to humans and, I believe, all victims have contracted the flu through some sort of direct contact with birds. Now, if the day comes when bird flu can be passed from human to human through airborne transmission that would be a frightening thing.
12
10
|
Re: Understandings of risk
Sun Dec 23, 2007 at 02:08:53 PM EST
4.00 (informative)
|
The Spanish Flu IS Bird Flu.
14
12
|
Re: Understandings of risk
Sun Dec 23, 2007 at 08:25:20 PM EST
|
I suppose I should have said it was an influenza A bird flu. I suppose it's possible to make the case that only the A(H1N1) subtype is really dangerous and A(H5N1) is really nothing to worry about. The data really doesn't exist to prove one way or the other, because most of the deaths occur in rare events and we haven't sequenced them farther back than the 1918 virus.
