1. A pandemic (from Greek παν pan all + δήμος demos people) is an epidemic of infectious disease that spreads through populations across a large region; for instance a continent, or even worldwide.

2. epidemic (from Greek epi- upon + demos people) occurs when new cases of a certain disease occur in a given human population, during a given period, substantially exceed what is "expected," based on recent experience (the number of new cases in the population during a specified period of time is called the "incidence rate").

3. sporadic: occurring occasionally, singly, or in irregular or random instances

4. carrier a person, animal, or plant that harbors and transmits the causative agent of an infectious disease; especially : one who carries the causative agent systemically but is asymptomatic or immune to it

5. reservoir an organism in which a parasite that is pathogenic for some other species lives and multiplies without damaging its host; also : a noneconomic organism within which a pathogen of economic or medical importance flourishes without regard to its pathogenicity for the reservoir

6. vector an organism (as an insect) that transmits a pathogen from one organism or source to another 3 : an agent (as a plasmid or virus) that contains or carries modified genetic material (as recombinant DNA) and can be used to introduce exogenous genes into the genome of an organism

7. contact union or junction of body surfaces

8. Contamination is the presence of a minor constituent in another chemical or mixture, often at the trace level. In chemistry, the term usually describes a single chemical, but in specialized fields the term can also mean chemical mixtures, even up to the level of cellular materials.

9. Isolation the action of isolating or condition of being isolated 2 : a segregation of a group of organisms from related forms in such a manner as to prevent crossing

10. Infection an infective agent or material contaminated with an infective agent2 a: the state produced by the establishment of an infective agent in or on a suitable host b: a disease resulting from infection: an act or process of infecting also : the establishment of a pathogen in its host after invasion

11. Infectious disease a disease caused by the entrance into the body of organisms (as bacteria, protozoans, fungi, or viruses) which grow and multiply there

12. Communicable disease an infectious disease transmissible (as from person to person) by direct contact with an affected individual or the individual's discharges or by indirect means (as by a vector)

13. Contagious disease an infectious disease communicable by contact with one who has it, with a bodily discharge of such a patient, or with an object touched by such a patient or by bodily discharges

14. Incubation period the period between the infection of an individual by a pathogen and the manifestation of the disease it causes

15. Suspect One which is suspected, especially of causing a condition, disease, or injury

16. Prodromal period The time during which a disease process has begun but is not yet clinically manifest.

17. Vehicle of transmission an organism (as an insect) that transmits a pathogen from one organism or source to another