A mechanism of transmission of an infectious agent by particle, dust or
water droplets suspended in the air.
Case:
A person in the population or study group identified as having a particular
disease.
Common Vehicle Spread:
Transmission of an infectious agent from a source that is common to those
who acquire the disease. The common source may be water, milk, food, air,
or syringes contaminated by infectious or noxious agents.
Communicable Disease:
An illness due to a specific infectious agent or its toxic products that
arises through transmission of that agent or its products from an infected
person, animal, or reservoir to a susceptible host, either directly or indirectly
through an intermediate plant or animal host, vector, or the inanimate environment.
Communicable Period:
The time during which an infectious agent may be transferred directly
or indirectly from an infected person to another person, from an infected
animal to man (rabies), or from an infected person to an animal.
Community:
A group of individuals organized into a unit, or manifesting a unifying
trait or common interest. A community could be the catchment area population
for which a service is provided, or more broadly, a province or country.
Control:
Ongoing operations or programs aimed at reducing the incidence of disease
or eliminating it.
Crude Rate:
The number of cases or deaths per 100,000 persons per year without adjusting
for age or other potential confounding factors.
Ecumene:
A geographic term for significantly inhabited regions. Populated areas
are shaded in their appropriate colour providing they have a minimum population
density of about 0.4 person per square kilometres (approximately 1 person
per square mile).
Endemic:
The constant presence of a disease or an infectious agent within a given
geographic region or population group.
Epidemic:
The occurrence in a community or region of cases of disease clearly in
excess of normal expectancy. The community or region, and the period in which
the cases occur, are specified directly. The number of cases indicating the
presence of an epidemic varies according to the agent, size and type of population
exposed, previous experience or lack of exposure to the disease, and time
and place of occurrence. An epidemic is relative to usual frequency of the
disease in the same area, among the specified population, at the same season
of the year.
Epidemiology:
The study of the distribution and determinants of disease in specified
populations, and the application of this study to the control of disease.
Descriptive Epidemiology:
General observations concerning the relationship of disease to basic characteristics
such as age, sex, race, occupation, and social class; also concerned with
geographic location.
Fomites:
Articles which convey infection to others because they have been contaminated
by disease-causing organisms. Examples include a drinking glass, a door handle,
and toys.
Histogram:
A graphic representation of the frequency distribution of a variable.
Incidence:
The number of new instances of illness commencing, or of persons falling
ill, during a given period in a specified population.
Incidence Rate:
The rate at which new cases of disease occur in a population. The numerator
is the number of new cases of disease occurring in a given period; the denominator
is the population at risk of acquiring the disease.
Notifiable Disease:
A disease deemed of sufficient importance to public health to require
that its occurrence be reported to public health officials. The reporting
of notifiable diseases is mandated by the provinces and territories; notifiable
diseases may vary from province to province. Reporting by the provinces and
territories to the federal level is voluntary; however, agreement is reached
by consensus of the Advisory Committee on Epidemiology (ACE), which comprises
representatives from all provinces and territories.
Number of Cases:
The number of cases/deaths of a disease in a given time period.
Public Health Surveillance:
The ongoing, systematic collection, analysis and interpretation of data
essential to the planning, implementation, and evaluation of public health
practice, closely integrated with the timely dissemination of these data
to those responsible for prevention and control.
Rate:
The proportion of a group affected over a period of time. For notifiable
diseases, the period of time is one calender year (January 1 to December
31). It is usually expressed as the number of new cases per 100,000 people
per year.
