ABSTRACT

Infectious diseases arise from microscopic organisms, or fragments of such life, which interact with cells in ways that cause dysfunction to occur. The microscopic organisms are called bacteria, if they can reproduce on their own (outside of a host cell), and are called viruses if they need to commandeer the DNA of another cell to affect reproduction. Recently, mere fragments of protein, called prions, have been found to cause disease (Prusiner, 1995). These entities reproduce purely enzymatically, without any genetic code at all. All of these different kinds of disease "vectors" can cause cells to fail in some way that results in illness or death to a larger host organism.