Glossary

adaptation
A biological characteristic that improves the chance of survival of an organism and its descendants.
antigen
Any foreign substance that when introduced into the body stimulates an immune response.
antigenic drift
The appearance of mutations in a virus' genome as it replicates over time.
epidemic
A widespread outbreak of an infectious disease where many people are infected at the same time.
evolution
The scientific theory for how groups of living things change over time.
gene
An inherited piece of information contained in a cell's DNA. The information from each gene is used to make a unique type of protein, which has a specific function for the cell.
genetics
The scientific study of heredity. Also, the genetic constitution of an individual, group, or class.
immune system
The parts of the body that prevent and fight disease.
microorganism
Any organism that can only be seen with a microscope; protozoans, bacteria, fungi, and viruses are examples of microorganisms.
mutation
A change in a gene´s structure that may be passed on to future generations.
nucleotide
The basic structural unit of nucleic acids (DNA or RNA).
outbreak
The occurrence of a large number of cases of a disease in a short period of time.
pandemic
An epidemic that affects multiple geographic areas at the same time.
pathogen
Any disease-producing agent; such as, viruses, bacteria, or other microorganisms.
population
A group of organisms of one species, occupying a defined area and usually isolated from similar groups of the same species.
prophylactic
Preventive measure or medication.
protein
Any of a group of complex organic compounds which contain carbon, hydrogen, oxygen, nitrogen and usually sulfur, the characteristic element being nitrogen; widely distributed in plants and animals.
reassortment
The exchange of genetic material between two viruses inside a cell of an organism.
reservoir host
A host that carries a pathogen without injury to itself and serves as a source of infection for other host organisms.
RNA (ribonucleic acid)
A nucleic acid that governs protein synthesis in a cell.
species
A group of individuals, usually identifiable by a set of distinctive features, with a unique evolutionary history. Classically, the members of a species can interbreed only with each other to produce fertile offspring.
vaccine
A substance that contains antigenic components, either weakened, dead or synthetic, from an infectious organism which is used to produce active immunity against that organism.
vector
An organism that transmits a pathogen.
virulence
The degree or ability of a pathogenic organism to cause disease
virus
An ultramicroscopic infectious agent that replicates itself only within cells of living hosts.