Disease, Infections, and Antibiotics, Part I

 

Today we move from talking about computer and network technology to a completely different topic: disease, infections, and antibiotics.

 

First off: explain what a bacteria is (gram positive vs. negative, cocci vs. bacilli) and viruses. Illustrations: http://www.ucmp.berkeley.edu/bacteria/bacteriamm.html

 

Then:

1. Disease has been around for thousands, or even millions, of years.
2. Many bacterial and viral diseases may actually be mistakes! Organisms that either work with us (symbionts) or even those that mooch off us (parasites) work better if they don't kill us!
1. Examples: E. coli; various other parasites. In fact, there is strong evidence that many diseases are not as bad now as they once were.
2. Lots of things live on us/in us which could make us sick, but only do so "opportunistically." (see http://www.bact.wisc.edu/Bact303/Bact303normalflora)
3. Our book takes something of old-fashioned view about the history of medicine. It assumes that medical treatment prior to roughly the turn of the century was all deadly.
4. This is probably not exactly the case. Results were highly variable, and depended on where you were. Some cultures are better at treating some things than others!
1. Example: Egyptians using moldy bread for wounds
2. Example: Chinese acupuncture. Also, basic small pox vaccine.
3. Example: just not doing anything, except "the usual": rest, fluids, etc.
4. Example: willow bark tea in America, a folk remedy for fever. (Contains a natural form of aspirin.)
5. Even bleeding can help a few illnesses, believe it or not.
5. Note, too, that two things dramatically aggravate the situation: large populations (over 60,000) and travel. Note Columbus's effect on America, w/ measles, smallpox, and flu.

 

6. Important early people:
1. Leeuwenhoek (Dutch): first decent lenses and observations of microscopic things
2.  Jenner (English): First decent smallpox vaccine in the west. Used cowpox. (Used his own son for experiments! L )
3. Pasteur (French): Does lots of things, including a rabies vaccine.
4. Semmelweis (Austria) and Lister (Scotland) develop antiseptics.
5. Koch: staining bacteria, among other things.

 

7. Treating actual diseases:
1. Ehrlich (German): combines a dye with arsenic in 1910 to combat syphilis.  The first "chemotherapy."
2. G. J. Domagk (German/Polish): first antibiotic--sulfa drugs! Saves the life of his own daughter. In wide use by the mid-1930's, and saved millions of lives.
3. Flemming/Florey/Chain (Scottish and British): Penicillin! Note, however, that it was Pfizer in the U.S. (in Peoria, Illinois!) who actually got it to work well enough for wide use. 
4. Schatz/Waksman (U.S.): streptomycin, which cured things at penicillin couldn't. (However, it is also more toxic.)

 

8. Vaccines and antibiotics have had a tremendous impact on our daily lives. Many of us--and many of our children--would not be alive today without them!! Also allowed the sexual revolution, for better or for worse. However, there are problems:
1. Vaccines can take a long time to produce, and not everything can be treated with them. Some diseases mutate quickly (like the flu); others change so quickly, or have so many varieties, that you can't make a vaccine (like the common cold).
2. Some diseases are not caused by the germ, but by the body itself (some forms of hepatitis, rheumatic fever).
3. Perhaps worst of all, our antibiotics are losing effectiveness. Reasons:

                                                               i.      patient allergies increasing over time.

                                                             ii.      lots of antibiotics exist, but they cannot be used internally.

                                                            iii.      overuse, esp. against things live viruses (colds, etc.) where they don't even work.

                                                           iv.      bacteria getting smarter, by swapping DNA.

                                                             v.      worst of all: tremendous overuse in farm animals.

4. People are now looking for new ways to kill the germs:

                                                               i.      new antibiotics from sharks and frogs.

                                                             ii.      phages, which are viruses that attack bacteria.

                                                            iii.      nanobubble, which seem to be depth charges for bacteria! (Stay tuned on this one…)

 

 

From http://www.botany.hawaii.edu/faculty/wong/BOT135/Lect23.htm

There are 100,000 tons of antibiotics produced, world-wide, each year, with gross sales that amount to $4.2 billion, in1980. The annual gross, in the United States alone is $1 billion. Most of the sales involve cephalosporin, ampicillin and tetracyclines. Note that  penicillin is absent from this list, and even though it is the most well known and its use is still very important in medicine, it is not among the top three antibiotics, with respect to sales. Although the antibiotics that are, in use, are of great economic significance, a great deal of expenditure is also utilized in the development of new antibiotics.

Prior to 1960, approximately less than 5% of the antibiotics developed were useful. In the following years, the number of antibiotics discovered remained constant, but the number of antibiotics that actually came on the market decreased to 2.6% between 1961-65, and between 1965-1971, dropped to 1%. The reason for the drop was due to cost. The average cost of developing an antibiotic is between $10,000,000-$20,000,000 and 8-10 years of time and resources. Thus, this decrease, in products being marketed, can be attributed to increase in cost of development and clinical testing, and other resources utilized in developing antibiotics. The pharmaceutical manufacturers now only market those products that they believe will be most clearly of value in therapeutic treatment.

9. What about viruses?
1. Viruses are generally much, much smaller than bacteria.
2. They are like little mines, drifting along until they come in contact with a cell.
3. Not only do they make us sick with colds, they can cause cancer (up to 20%--HPV, HCV.). They may also be responsible for some types of kidney disease, high blood pressure, etc.
4. However, simply staying clean may not be the whole story… note polio, for example!
5. Most viruses are very specific--they can only infect one type of cell (such as liver cells, in the case of hepatitis) in one type of organism (say, humans). They are also extremely variable in how contagious they are.
6. A few can "jump" between species:

                                                               i.      colds

                                                             ii.      the flu

                                                            iii.      sometimes AIDS or (ugh!) ebola

 

10. Viruses are all over the place. While they don't really do anything creative, they may be responsible for moving genes around between species. Some think that 95% of our DNA is "junk" viral DNA! (nature's own version of "spam…?"

 

11. The book spends a chapter talking about "emergent" killer viruses like ebola. Note, however, that super-lethal viruses MAY not be as easy to spread as one would think, because it kills the host before it can spread. And the worst (SO FAR) seem to require some sort of exchange of bodily fluid, either sexually or by needles (ebola, HCV, AIDS).

 

12. However, is somebody or something let loose any easy-to-spread version of ebola in New York or London, this could be devastating. We will talk more about this later, however.

 

13. Perhaps more significant are the "common viruses" that we are more used to hearing about: influenza, hepatitis, polio, measles. (Note that smallpox is probably gone.) Note the concept of a "reservoir" for some viruses (flu) but not others (smallpox, polio). If animals can get it, it is much harder to get rid of it. This may be especially true in Asia, due to their intensive farming practices.