CSP: broad class of diseases whose causative agents may be passed between individuals in many different ways.,NCI: Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body's natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.,NCI: A disorder resulting from the presence and activity of a microbial, viral, or parasitic agent. It can be transmitted by direct or indirect contact. -- 2003 (NCI),MEDLINEPLUS: Infectious diseases kill more people worldwide than any other single cause. Infectious diseases are caused by germs. Germs are tiny living things that are found everywhere - in air, soil and water. You can get infected by touching, <a href='http://www.nlm.nih.gov/medlineplus/foodborneillness.h