Dictionary

visceral pericardium The inner layer of the pericardium.

visceral leishmaniasis See leishmaniasis.

virus, attenuated A virus that has been weakened. A vaccine against a viral disease can be made from an attenuated, less virulent strain of the virus: a virus that is capable of stimulating an immune response and creating immunity but not of causing illness.

virus A microorganism that is smaller than a bacterium that cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations); this ability to mutate is responsible for the ability…

virulent Extremely noxious, damaging, deleterious, and disease causing (pathogenic); marked by a rapid, severe, and malignant course; poisonous.

virulence The ability of an agent of infection to produce disease. The virulence of a microorganism is a measure of the severity of the disease it causes.

virology The study of viruses.

virion A virus particle.

viremia The presence of a virus in the blood. Viremia is analogous to bacteremia (the presence of bacteria in the blood) and parasitemia (the presence of a parasite in the blood). Viremia, bacteremia, and parasitemia are all forms of sepsis (bloodstream infection).

viral infection An infection caused by the presence of a virus in the body. Depending on the virus and the person’s state of health, various viruses can infect almost any type of body tissue, from the brain to the skin. Viral infections cannot be treated with antibiotics; in fact, in some cases the use of…

viral hepatitis See hepatitis, viral.

viral Of or pertaining to a virus. For example, if a person has a viral rash, the rash was caused by a virus.