Infection is the invasion of an organism’s body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is an illness resulting from an infection.
Infections can spread, directly or indirectly, from one person to another. Many are caused by pathogenic microorganisms such as bacteria, viruses, parasites or fungi. Other infections can be caused by agents such as prions. Infection is distinct from contamination, which is the presence of a pathogenic organism or other harmful agent on a surface or object.
