deoxyribonucleic acid, a carrier of genetic information (i.e., hereditary characteristics) found chiefly in the nucleus of cells.

DNA virus

a virus that contains only DNA as its genetic material.

droplet nuclei

the very small particles of moisture expelled when a person coughs, sneezes, or speaks that may transfer infectious organisms to another person who inhales the droplets.



enzyme-linked immunosorbent assay. An immunological technique used for the quantitation of antigen or antibody in a sample such as blood plasma or serum. In the assay, enzyme-labeled antigen or antibody is bound to a solid surface (such as beads, tubes, or microplate wells). After addition of the sample and a substrate, the presence of the desired antigen, antibody, or antigen-antibody complex is indicated by a color change based on a reaction of the enzyme with the substrate.


the condition in which a disease is present in a human community at all times.


developing or originating from within the individual.


refers to a disease (can be either low or high morbidity) that is endemic in an animal community.


the condition in which a disease spreads rapidly through a community in which that disease is normally not present or is present at a low level.


a disease of generally high morbidity that spreads rapidly through an animal population.

escape mutant

refers to the formation of a mutation in a population of microorganisms that allows the mutant organism to escape the immune response directed against it.

etiologic agent

the organism that causes a disease.


the cause or origin of a disease.



a class of antibiotic.


genetic adaptability

the ability of a microorganism to adapt to its environment, often allowing it to avoid detection or an immune response generated against it.


the complete genetic composition of an organism (e.g., human, bacterium, protozoan, helminth, or fungus), contained in a chromosome or set of chromosomes or in a DNA or RNA molecule (e.g., a virus).


refers to the inability of a microorganism to accept a certain stain. This inability is related to the cell wall composition of the microorganism and has been useful in classifying bacteria.


refers to the ability of a microorganism to retain a certain

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement