The Gap Between Stats and Understanding In Flu Cases

KentuckyFC writes "Bird flu gets all the headlines but ordinary flu kills several orders of magnitude more people each year and represents a significant threat to our society. The frightening thing about ordinary flu is how little we understand about how it spreads. According to a report at the physics arXiv blog, researchers trying to model this process say they still don't know some basic probabilities associated with infection (pdf, abstract). For instance, given that the disease has manifested itself clinically in an individual, what are the chances of that person dying? And if a virus can be caught from a number of different host species (as it might eventually be with bird flu) what is the probability of transmission?"

Comments

Re:Is ordinary flu that dangerous?

[Eukariote]

So investing time and money into understanding and combating both types of flu is understandable.

Indeed, infectious diseases should be carefully researched and closely monitored. But does that warrant the scare mongering enacted in the public media concerning flu and bird flu when the actual risk is very very low in comparison to other common risks? And does that low risk warrant the side effects and cost of all those yearly flu shots people are given?

Why not verify the data that is supposed to show that vaccines are even effective? Here is a book to help you out with that http://astore.amazon.com/medical-bookstore-20/detail/1881217302. Yes, you can interpret statistics in many ways, but the fact of the matter is that vaccines have been sold to the public and policy makers based on statistics of infectious disease reductions that occurred with improvements of hygiene, not with the later introduction of vaccination programs.

Re:how about doing what nature intended instead

[theshowmecanuck]

In one sense I totally agree with you. We need to exercise our "natural" immune system in order for it to become stronger. On the other hand, part of human evolutionary adaptation gave us the ability to modify our situation/environment.

With respect to the bird flu (being mentioned a lot in the replies), one of the best observations I have heard is that the real bird flu threat is the one you contract from KFC and McDonalds Chicken Nuggets, et al. Heart disease and obesity. That probably kills far more than all influenzas and pneumonias in the U.S. and Canada each year. :) A lot of people will need to become immune to all the advertising for that epidemic to die down.

fears seem well placed

[khallow]

Let's take a look at the last century. As I see it, roughly half of the people who died of flu, did so in the 1918 pandemic. In other words, one single variant of the flu killed as much as a century's worth of regular flu. It makes no sense to ignore a flu variant which to all appearances is more lethal than the 1918 flu (all we know is that more than half of the people who we figure out had it die which is much worse in general than the 1918 flu was), even if it is barely contagious. Obviously, there might be a big drop in lethality, if it adapts to humans. But if there isn't, and as in the 1918 flu epidemic, it infects about 20% of humanity (as I dimly recall), then that means 10% of humanity dies (as opposed to about 2% for the 1918 flu).

In fact, things are much worse now

[Kupfernigk]

In 1917-18 human mobility was much less than it is now, and a much lower percentage of humanity lived in large cities. Cheap air, bus and train travel mean that viruses can spread much faster than they could in 1918. Also, the fear of disease is much less and people will less willingly take precautions against exposure. Given the short exposure needed and the rapid incubation of the influenza virus, the spread could be so rapid as to overwhelm government agencies and hospitals. The Black Death reduced the population of medieval Europe by more than a third.

Recent tests of symptomatic treatment of influenza have shown that this doesn't work, i.e. the lethality of the virus is based on its primary action. Given that governments will probably be too afraid or powerless to stop all air travel and movement from affected areas when it starts, this could realistically happen again.

The worst of it is that it will probably start in China , where a major population reduction would probably suit the Communist Party down to the ground. The survivors would be too busy reconstructing society to think about revolution, and the pressure on resources would suddenly drop dramatically. Provided they could protect themselves, the leaders of China would have little reason to try and stop a world wide influenza pandemic.

It's not the shot themeselves.

[DrYak]

It's the vaccine that may be the cause of the arthritis, it may be the adjuvants.

One doesn't develop systematically antibodies against everything that gots injected under the skin. How otherwise would you explain that no reaction happen (most of the time) following tatoos ? That people who develop antibodies against bioengineered drugs only develop them over time (and not right at the first exposure) ?

For the white cells to react, the intruder must be flagged as something worthy of a reaction, otherwise the intruding substance just gets cleaned up silently by macrophages.
For actual microbes (viruses and bacteria) that is mainly due to the destruction they cause. This damage triggers and inflamation which stimulates the immune response.
But a lot of vaccine are often only bioengineered inert proteins. They don't atract the lymphocyte's attention and may end up silently cleaned up. On of the technique consist to ad a special substance that will increase the probability of an immune response, that will boost the tendency of the body to react and produce antibodies.
The problem is that some adjuvant bring a small risk that the bodies over reacts and is stimulated to produce antibodies against other things too, like against it self and thus the dogs in the experiment you mention develop arthritis.
But that depends on the quantity of vaccines they got exposed too, and the composition of the vaccine regarding the response-boosting adjuvants.
Regularly old adjutants (either preservatives or boosters) get phased out and replaced by newer safer methodology.

But the process of vaccination (producing antibodies against foreign substance) isn't dangerous per se. And anyway is happening all the time continuously, whether or not someone gets shots by his doctor or not. If your not sick for long periods of time, that's not because you managed to somehow avoid all bacteria, it's just that your immune system is at work and manage to correctly handle continuously all pathogens present in your everyday environment.

Autoimmune diseases are also at increased risk after a disease, because the immune system got stimulated (and also because of the mimickery some bacteria use to try to hide - Antibodies that work against them may end up working against the body)

Lastly, autoimmune disease depends mainly on the genetic make-up of an individual. There are people at greater risk of autoimmune response and people at lower risk (also for various reason I won't detail here, being female doesn't help). And as I said before, if your at risk (have several family members with diseases like arthritis, lupus, psoriasis, etc.) running away from vaccine won't help, you could develop some as a consequence of a disease.

About Allergy : They are not caused by a depressed immune system. They are a (bad) reaction of the immune system and for that you need a working one. Once again it depends on the individual genetic markup.
But as you point out environmental exposition may play a role in the balance.
The cells involved in allergy (eosinophils) seem to normaly be usefull against parasites. In third world countries, those cells get someting to work on and thus remain busy. In our clean occidental settings, they stay useless. In some people, those cells just stay calm and don't do much. But in people with the wrong genes, the cells may try to work too much and do things they aren't supposed to : this bring you allergy (and the problem with allergy is, unlike a parasites which usually is 1 animal in 1 precies location, the allergenic substance can get in your blood and disseminate and trigger response in the whole body thus provoking anaphylaxis).

Note that, as mentioned before, some way to stimulate the immune response is needed in allergy too. Often this is linked to a family of proteins like lysozyme in the saliva of animals whose fur causes allergy (those proteins are used to kill bacteria but might be very slightly reactive in humans and thus trigger a response).

Probably (as pointed