A medical question

D

Darth_Infernus

Disciple
Okay,

I hope this one doesn't turn out the same way as my previous thread did, and I hope THIS is a better topic to talk about.

Well, we see nowadays that some viruses and bacteria which cause diseases are growing resilient to drugs. Now the question I ask is: When these tiny bacteria and viruses are able to adapt themselves to be able to resist drugs (i.e. evolve), why can't our body made of thousands of cells evolve to better resist such bacteria/viruses?

For example, many of us have caught the flu more than once in our life. Malaria, Typhoid, Jaundice all have a chance of re-occuring in your body if one does not take the proper care. If our body was resisting these, then with each infection the effects of the disease should become less and less to the point that our body will be able to effectively repeal any virus/bacteria that tries to infect the body. However, this is not the case at all.

Now, in my discussions with a medical student, I learnt that the body is able to adapt itself to an extent that for certain bacteria, it can create some antibodies which will destroy the next infection bacteria which causng the same disease within 2 seconds. However, he also said that this does not work for all kinds of bacteria/virus.

Now, can anyone here studying/practising medicine elaborate on WHY the human body is not evolving to resist such infections? I mean, diseases are not an uncommon thing, and when some problem becomes common, usually the body must evolve to get around this "obstacle" to their fitness and health. It is only due to drugs and medicines that we are able to survive today. Many diseases have been known for quite a few years now and not a single time has there been any proof that humans have evolved to resist such diseases. It is only through evolution that we are what we are, and so it is natural that we should evolve to be above and beyond the vulnerability caused by diseases without using drugs or medicines.

Can anyone tell why? I know, its kind of a complex question, but I hope I can get a clear answer here. :)
 
evolution comes thru procreation.

bacteria multiply quickly and so the chances for their genes to mutate are much higher, with the genes improving with each generation on a much faster rate.
 
well actually virus feds on your body's resources, making you weak and more unhealthy, like a cycle, ofcource you can be immune to certain bacterias but viruses are a different matter.
 
The reason that our body is unable to adapt to certain diseases is because many diseases require our body to lower it's shields first, either through poor eating habits or hygiene. Something that our body really can't do much about no matter how many times you suffer the disease.

Also, genes don't retain information about immunizing against diseases.
 
well there is no simple answer to such a situation....

viruses n bacteria have many mechanims by which they evade the immune system and drugs....
for example....the hiv virus infects and mutiplies inside the very cells used by the body to fight an infection...and as the virus mutiplies inside a cell they baby viruses(the progeny) maybe never leave the cell infact it will just pass from within one cell to inside of another cell....never been exposed to the actual immune response...

Also the DNA n RNA structure of most viruses n bacteria is quite simple as compared to the human genome and simple additions or deletions of nucleic acids may change the stucture of the infecting organism...
eg : the influenza virus undergoes slight genetic change every 10 yrs or so which leads to drugs resistance and flu pandemics...

Also for our immune system to be able to distinguish between self n foreign organisms....the foreign organisms have to have certain characters which will identify them as foreign...if an orgamins alters a characteristic which usually points to it beign forgein it becomes difficult for the immune system or drugs to identify the organism as a threat...

Another example is that similar bacteria or viruses might be able to exchange or transfer certain properties to to each other (i.e from bactria to bacteria) by certain processes which can make a previously non infections organism infectious....
Well these just some of the mechanisms....
 
You'd think our human _brains_ should've evolved by now to stop warring and work towards the development of mankind, helping the environment, elimination of poverty, raising the standard of society..
 
plus bacteria are smaller forms of life = less cells , they can change easy ..... human body has to trouble shoot a lot of mechanisms to find the problem and then fight it
 
Evolution in many celled organisms takes significantly longer than in a single celled organism simply because there are too many cells present.

Plus the life cycle of an RBC is 120 days which prevents it from evolving since 120 days is too less of a time to evolve.

The trouble with the HIV virus is that it mutates rapidly, therefore its difficult to combat it with simple medicines. What might be effective one day, will ease to be affective the other day because the damn thing has changed itself.

"""it can create some antibodies which will destroy the next infection bacteria which causng the same disease within 2 seconds"""

What he explained is a phenomenon called passive immunity (I think, not touched bio for 3 years now, might also be active immunity).

What basically happens is that the first time you're exposed to an infection, the body takes time to detect it and takes even longer to initiate an imune response. However during this time the body is able to identify the antigens present on the organism.

An antigen is basically a substance which initiates an immune response, so the next time the same organism decides to infect you, the body recognizes the antigen and the resulting immune response is many times faster and stronger.

Passive immunity is the basis of vaccination, where heat killed/weakened bacteria are inserted into the body so that the body can identify the antigens and prepare a proper immune response once you're exposed to the real thing.
 
Also... These viruses, are now mutating at a much faster rate due to fighting the medicines that we take, so this causes them to become a lot stronger and more resistant.

This isn't a perfect analogy.. but it works on a more basic level...

Take shaving for example... when men first start shaving their faces, their facial hair is somewhat sparse, and not very thick... but the more you shave the faster and thicker the hair grows back.

The viruses today are stronger and harder to kill because they are more resistant to anti-virus's/vaccines... etc...

The common cold or flu today, is far more severe than it was 100 years ago, there are people that believe that we should be avoiding things such as flu-shots, because in the long run it is going to spur the growth of super-flu's, that will be far more dangerous than the ones we have today.
 
biosbhai said:
evolution comes thru procreation.

bacteria multiply quickly and so the chances for their genes to mutate are much higher, with the genes improving with each generation on a much faster rate.
Click to expand...

I think that sums it up nicely (though its been 6 years I last studied genetics :ashamed: ).

There is a large population of bacteria; one of it by a recombination of genetic material develops resistance to the drug and is selected over others as the rest die in a hostile (antibiotic containing) environment.

The growth and multiplication of our body cells through cell division does not involve a genetic recombination. Genetic recombination occurs in the... what do you call it? (6 years!) ... the er.. 'sexual' cells in human which form by a cell division to reduce the chromosome numbers by half, to be brought back to the full number by combining with another cell from the other parent, leading to a new genetic combination.
 
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