Tachycardia - Rapid beating of the heart, conventionally applied to rates over 100 per minute.
Teratogenicity -The property or capability of producing fetal malformation.
Thrombocytopenia - A condition in which there is an abnormally small number of platelets in the circulating blood.
Toxoid - A modified bacterial toxin that has been rendered nontoxic (commonly with formaldehyde) but retains the ability to stimulate the formation of antitoxins (antibodies) and thus producing an active immunity. Examples include Botulinum, tetanus, and diphtheria toxoids.
Tracheitis - Inflammation of the lining membrane of the trachea.
Urticaria - An eruption of itching wheals, usually of systemic origin; it may be due to a state of hypersensitivity to foods or drugs, foci of infection, physical agents (heat, cold, light, friction), or psychic stimuli.
Vaccine - A suspension of attenuated live or killed microorganisms (bacteria, viruses, or rickettsiae), or fractions thereof, administered to induce immunity and thereby prevent infectious disease.
Vaccinia - An infection, primarily local and limited to the site of inoculation, induced in man by inoculation with the vaccinia (coxpox) virus in order to confer resistance to smallpox (variola). On about the third day after vaccination, papules form at the site of inoculation which become transformed into umbilicated vesicles and later pustules; they then dry up, and the scab falls off on about the 21st day, leaving a pitted scar; in some cases there are more or less marked constitutional disturbances.
Varicella - An acute contagious disease, usually occurring in children, caused by the varicella-zoster virus, a member of the family Herpesviridae, and marked by a sparse eruption of papules, which become vesicles and then pustules, like that of smallpox although less severe and varying in stages, usually with mild constitutional symptoms; incubation period is about 14 to 17 days. Syn: chickenpox
Variola - Syn: smallpox.
Variolation - The historical practice of inducing immunity against smallpox by “scratching” the skin with the purulency from smallpox skin pustules. The first inoculation for smallpox is said to have been done in China about 1022 B.C.
Viremia - The presence of virus in the bloodstream.
Virion - The complete virus particle that is structurally intact and infectious.