module 5 Flashcards
what is epidemiology
examines determinants and sitribution of diseases, disabilities, morbidity, mortality, as well as health
core functions include
- public health surveillance
- field investigation
- analytic studies
- evaluation
- linkages
- policy development
what are the three components of the epidemiological triangle
environment, agent, and host
what is the chain of causation
- still includes he triad of host, agent, and environment
- begins by idenitfying the reservoir (where the causal agaent can live and multiply)
- has a portal of exit from reservoir as well as some mode of transmission
web of causality
- focus moved from communicable, infectious didsease to non infectios and conditions
- well suited for chronic disease
incidence
- refers to all new cases of a disease or health condition appearing during a specified point in time or over a period of time
- the primary value of incidence rates is in studies of disease etiology, by comparing how the rates vary among different subgroups or with different exposures
prevalence
- is the number of cases (both newly diagnosed and previously diagnosed in current survivors) within a given population in a defined time period
- reflects the penetration of a particular disease or event within a population and can be used to evaluate the impact that treatments are having on a particular disease
- prevalence data provide an indication of the extent of a health problem. this is useful for determining the health burden in a population and the scope of health services and resources needed in a community such as facilities and personnel
morbidity
presence of disease in a population
mortality
refers to the occurrence of death in a population
passive immunity
refers to short-term resistance that is acquired either naturally or artificially. Newborns, through maternal antibody transfer, have natural passive immunity that lasts up to 1 year for certain diseases
active immunity
long-term and sometimes offers lifelong resistance that is acquired either naturally or artificially.
Naturally acquired active immunity comes through host infection. That is, a person who contracts a disease often develops long-lasting antibodies that provide immunity against future exposures.
Artificially acquired active immunity is attained through vaccine inoculation. (ex. vaccines for polio, diptheria, smallpox, etc)
cross immunity
refers to a situation in which a person’s immunity to one agent provides immunity to a related agent as well. The immunity can be either passive or active. Sometimes, infection with one disease, such as cowpox, gives immunity to a related disease, such as smallpox.
herd immunity
describes the immunity level that is present in a population group.
A population with low herd immunity is one with few immune members; consequently, it is more susceptible to a particular disease. Nonimmune people are more likely to contract the disease and spread it throughout the group, placing the entire population at greater risk. Conversely, a population with high herd immunity is one in which the immune people in the group outnumber the susceptible people; consequently, the incidence of a particular disease is reduced.. The level of herd immunity may vary with diseases. For instance, a level of community immunity of between 83% and 85% may be necessary for rubella, but for diphtheria a level of 85% may be effective.
Mandatory preschool immunizations and required travel vaccinations are applications of the herd immunity concept.
4 basic epidemic control steps for infectious disease
testing: allows public health officials to identify who has a specific communicable disease and if they can spread it to others. Presence of symptoms is not an accurate way to identify the presence of disease
isolating: Isolating those who are positive for the disease from others
quarantine: Isolating those who have been in contact with a positive person but does not yet have a positive result or symptoms. It does seek to control the movement of the person to decrease spread
tracing: The process of identification of persons who have come in contact with an infected person and subsequent collection of further information about those contacts. This is done for all types of infectious diseases that are known to be person-person spread
what are some goals of communicable disease control
Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrheal diseases
Elimination of disease: Reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberate efforts; continued intervention measures are required. Example: neonatal tetanus
Elimination of infections: Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis
Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox
Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none
what is relative risk ratio
statisically compares the disease occurrence in the population at risk with the occurrence of the same disease in people without that risk factor
assists in determining the most effective points for community health intervention in regard to particular health problems. It also provides a more easily understood method for explaining the risk of certain behaviors in the development of illness or injury to the public
