The world of infectious diseases and the agents that cause them is not so foreign if we take a little time to explore it.
Most of us will probably catch a cold this year. Someone in our family may come down with the flu as well. Those of us over 35 probably remember fevers, headaches, stomachaches, itching skin, and swollen glands as we suffered through the inevitable childhood diseases: mumps, measles, chicken pox, and perhaps others. We learned that by having the disease as children, we were building up immunity so we wouldn't have to suffer later.
Today, most American children are immune to those diseases. Thanks to childhood vaccinations, they have built up immunity without becoming ill. On the other hand, many common illnesses such as coughs and earaches afflict these children and cause sleepless nights for their parents. As treatment, children receive a course of antibiotic, prescribed for a period of days. However, when the symptoms fade in a few days, parental anxiety is relieved and the natural tendency is to stop giving the antibiotic. Thus parents and children treating a cough or ear infection, along with countless others who are prescribed an antibiotic course, unwittingly assist the microbial world to overcome our defensive weapons.
By discontinuing the treatment prematurely, we fail to kill all the microbes, leaving behind those survivors that are best able to withstand the antibiotic. Our priorities do not include fighting invisible and apparently harmless enemies. But the microbes are relentless. Their constant priority is to seek out advantageous living conditions and exploit available resources to achieve maximum growth and multiplication. Thus they turn every human lapse in treatments to a microbial advantage, adapting now just as they have been doing for hundreds of millions of years.
Deseases and disease agents
The roster of infectious diseases is imposing: measles, malaria, hepatitis (A, B, C, E, or G), sleeping sickness, cholera, leishmaniasis, AIDS, tuberculosis, …