I. DEFINITION OF TERMS

Communicable Perioda time during which the infectious agent may be transferred directly or indirectly from an infected person to another person, or from an infected animal to man.

Contact - any person or animal known to have been in such association with an infected person or animal having the opportunity of acquiring the infection

COMMUNICABLE DISEASES

—  A  contagious disease transmitted by contact.

—  an illness due to a specific infectious agent or its toxic product arising through transmission of that agent either directly as from an infected person or animal or indirectly through the agency of an intermediate plant or animal host, a vector or the inanimate environment.

—  All ailments which may be transmitted by any means from person to person or from animal to person

Epidemiology -

—  The study of the distribution of a disease or condition in a population.

—  The science that deals with the inter-relationship of the various factors and conditions which determine the frequencies and distributions of an infectious process, a disease or a physical state in a human community.

Epidemiologist -  is a person vested in epidemiology who may also direct measures to control or prevent epidemics.

Channels of infection are means through which the body becomes infected by disease-producing agents. The channels may be the respiratory tract, the digestive tract, exterior surfaces of the body.

HOST. A person or other living organism that can be infected by an infectious agent under natural conditions.

Carrier is a person or animal without apparent disease who harbors a specific infectious agent and is capable of transmitting the agent to others.

Incubation period is the time from the moment of exposure to an infectious agent until signs and symptoms of the disease appear. For example, the incubation period of chicken pox is 14-16 days. `

II. IDENTIFICATION OF COMMUNICABLE DISEASES AND THEORIES OF EPIDEMICS

III. CLASSIFICATION OF CONTAGIOUS, INFECTIOUS AND COMMUNICABLE DISEASES, THEIR SOURCES AND CARRIER

Endemic is the term applied to a specific disease when it normally prevails in a locality and does not fluctuate markedly from the normal expected incidence in the community.

Epidemic is the incidence of a communicable disease among a number of people to an extent that is recognized statistically as being well beyond the normal expectancy for the disease in a community in a definite period of time.

Sporadic implies the occurrence of a few scattered cases of the disease without relationship to other cases; a few cases every now and then.

Pandemic affects large number of people at the same time and transcends community boundaries.

Epizootic - an epidemic among animals.

Zoonosis - an infection or an infections disease of animals transmissible under natural conditions to man.

https://www.ncbi.nlm.nih.gov/books/NBK470303/

http://www.acphd.org/communicable-disease/communicable-diseases.aspx