Contaminated objects harboring infectious agents.
The study of the causes of disease.
The cause/origin of disease.
This is the occurrence of a disease in a community or region of a group of illnesses, which is clearly more than the normal
occurrence or expectancy of a disease. Defining a disease as epidemic depends on the disease itself and it’s known
occurrence. Ten cases of small pox is an epidemic. Ten cases of influenza is not.
This is a disease or an infectious agent within a geographical area that is expected to be around to some degree. An example
of this is the plague. This is a disease that is endemic unless an outbreak occurs then it can become an epidemic.
This is a disease that exists throughout a wide area, such as the cities, countries or the world.
Isolated incidence of a disease.
Incidence Rate
= New cases of a disease in a population during a specified time period/ Persons at risk of developing the disease during that time period X 1000
Prevalence Rate
#?/Persons in the population at the time X 1000
Mortality Rate
= Deaths from all causes occurring in a
population during a given time. Period (year) / Average number of people in the population during that period (at midyear) X 1000
Morbidity Rate
= Cases of a disease existing at a particular time, or cases occurring in a defined period of time/ 100,000
Modes of Transmission/Exposure
Fecal/oral, droplet contamination, exudates of mucous membranes, bloodborne, vectorborne, dermal exposure, contaminated food/water, direct contact, contaminated fomites, secondary infection.
Incubation Period
The period between infection and the appearance of signs/symptoms of disease
Duration of Symptoms
Length of time symptoms last
A person or animal that harbors a specific infectious agent in the
absence of discernible clinical disease and serves as a potential source of
infection. The carrier state may exist in an individual with an infection that
is inapparent throughout its course (commonly known as healthy or asymptomatic
carrier) or during the incubation period, convalescence, and
postconvalescence of an individual with a clinically recognizable disease
(commonly known as incubatory carrier or convalescent carrier). Under
either circumstance, the carrier state may be of short or long duration
(temporary or transient carrier, or chronic carrier).3*
Asymptomatic carrier shows no symptoms/signs of illness. Can transfer disease to others.
The time needed to return to health after illness
Period of Communicability
The time period at which the disease can be transfer to others.
Intermediate hosts/vectors
Hosts in which the parasite is in a larval or asexual state.
AKA secondary host
Droplet Contamination
exposure to and inhalation of respiratory aerosols containing infectious agents
pathogens are passed from fecal particles of one host to the oral cavity of second host
Direct Transmission
direct contact, droplet contamination
Indirect Transmission
Animate objects (vectors), inanimate objects (vehicles, airborne, fomites).
Exudes of Mucous Membranes
Transmitted through mucous excretions from mucous membranes. (eyes, nose, ears, vagina, etc.)
Transmitted through blood
Transmitted by a vector
Dermal Exposure
Transmitted through the skin
Contaminated food/water
Ingestion of contaminated food or water. (vehicles)
Secondary Infection
An infection by a microorganism that follows an initial infection by another kind of organism.
contaminated fomites
contact with contaminated objects that are harboring infectious agents
direct contact