Any microorganism that infects the body and causes disease is called a Choose...parasiteinfection viruspathogen . Colds, flu, and hepatitis are infectious diseases caused by Choose...virusesbacteriaprotozoa worms , whereas pneumonia, typhoid fever, and gonorrhea are caused by Choose...virusesbacteriaprotozoa worms. Different kinds of Choose...virusesbacteria protozoa worms infect at least a billion people worldwide and another 300 million people are infected by water-borne parasites that cause serious disease. Antibiotics are used primarily to treat infections caused by Choose...viruses bacteria parasites worms, however, these microorganisms are becoming resistant to many previously effective antibiotics. For example, the drugs rifampin and isonazid, widely used to treat Choose...gonorrheapneumoniatuberculosishepatitis are no longer effective in many cases. Hepatitis is a disease of the Choose...liverpancreas stomach lungs caused by any one of several different viruses. The most serious forms of hepatitis are contracted from contaminated Choose...foodwater air blood.