seronegative

negative result in a serological test; that is, the inability to detect the antibodies or antigens being tested for.

seropositive

positive result in a serological test.

serotype

the characterization of a microorganism based on the kinds and combinations of constituent antigens present in that organism; a taxonomic subdivision of bacteria based on the above.

slow virus

any virus causing a disease characterized by a very long preclinical course and a very gradual progression of symptoms.

strain

a subgrouping of organisms within a species, characterized by some particular quality.

syndrome

a set of symptoms that may occur concurrently.

tubercle bacillus

the bacterium that causes tuberculosis, Mycobacterium tuberculosis.

variolation

a procedure, not used today, in which material from the pustule of an individual infected with smallpox (variola virus) was scratched into the skin of an infected person to induce immunity to the disease.

vector

a carrier, especially an arthropod, that transfers an infective agent from one host (which can include itself) to another.

vector-borne

transmitted from one host to another by a vector.

virulence

the degree of pathogenicity of an organism as evidenced by the severity of resulting disease and the organism's ability to invade the host tissues.

zoonosis

a disease of animals transmissible to humans.

zoonotic pool

the population of animals infected with nonhuman microbes that present a potential threat of transmission to humans.