|Battle Against Disease|
Harmful microorganisms enter the body in one of four ways:
|Through air, as in droplets of water from the nose or mouth (whooping cough, measles, mumps, influenza, tuberculosis and half of all human infections)|
|Through unclean food and polluted water (cholera, dysentery, typhoid fever, diphtheria, mad cow disease)|
|Through the bites of infected animals and insects (malaria, rabies, bubonic plague, Rocky Mountain spotted fever, Lyme disease)|
|Through direct personal contact (Ebola, herpes, syphilis, AIDS)|
Sometimes the bodys response is not strong enough to fight off the disease. Medical science has developed vaccines to bolster the immune system. Three types include
|Vaccines from live bacteria|
|Vaccines from dead bacteria|
|Vaccines from inactivated toxins produced by bacteria|
Some bacteria become harmless after being grown for awhile in a laboratory, and when injected can produce immunity. In the 1980s a leprosy vaccine was developed this way. Dead bacteria are used in the vaccination against whooping cough, and diphtheria and tetanus vaccines are made by growing the bacteria in a laboratory, isolating the toxins they produce, and inactivating these toxins.
Others ways we have prevented the spread of disease include treating sewage, preserving food, and purifying water.