Principles of Disease & Epidemiology and Disease Prevention Flashcards
Define the following: Pathogen, Pathology, Etiology
Pathogen - Disease causing organism
Pathology - Scientific study of disease
Etiology - Causative agent of a disease
Define the following - Infection, Disease and Host
Infection: Invasion or colonization of the body by pathogenic organism.
Disease - Abnormal state in which all or part of the body is not functioning properly.
Define the following - Infection, Disease and Host
Infection: Invasion or colonization of the body by pathogenic organism.
Disease - Abnormal state in which all or part of the body is not functioning properly.
Host - Organism that shelters and supports the growth of pathogenic organisms.
Define 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. (Eg. Diarrhoeal diseases)
Define 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 to maintain the reduction. E.g. neonatal tetanus
Define 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. E.g. measles, poliomyelitis
Define eradication and extinction
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. E.g. smallpox
Extinction - The specific infectious agent no longer exists in nature or in the laboratory (no example).
What are normal flora?
Microbes that are on or in a host, but do not cause disease. They can be transient or resident.
Define microbial antagonism and symbiosis
Microbial antagonism - Belief that normal flora benefit a host by preventing overgrowth of more harmful microbes - in vagina, ear and on skin.
Symbiosis - Close relationship between two different organisms.
Lis
List and define the various types of relationships
Commensalism - One organism benefits, the other is unharmed.(harmless)
Mutualism - Both organisms benefit. (Helpful)
Parasitism - One organism benefits and other is harmed (harmful)
Opportunism - Organism don’t cause disease unless appropriate condition exists (potentially harmful).
Give the classification of diseases based on transmissibility
Communicable diseases - Transmitted directly or indirectly from one host to another.
* Contagious diseases - Easily spread from one person to another.
Non-communicable diseases - Not spread from one host to another.
Classify disease based on frequency of occurrence (S.E.E)
Sporadic - Occurring irregularly, haphazardly from time to time and generally infrequently.
Endemic - The constant presence of disease or infectious agent within a given geographical area or population group.
Epidemic - The occurrence in a community or region of cases of an illness, specific health related behavior clearly in excess of normal expectancy
Classify disease based on frequency of occurrence
Classify disease based on frequency of occurrence (S.E.E.P)
Sporadic - Occurring irregularly, haphazardly from time to time and generally infrequently.
Endemic - The constant presence of disease or infectious agent within a given geographical area or population group.
Epidemic - The occurrence in a community or region of cases of an illness, specific health related behavior clearly in excess of normal expectancy.
Pandemic - An epidemic occurring worldwide, or over a wide area, crossing international boundaries and usually affecting a large number of people.
Classify disease based on severity
Acute - Develops quickly/lasts short time
Chronic - Develops slowly/lasts long time
Subacute - In between acute and chronic
Latent - causative agent remains inactive for a period of time and then becomes active to produce symptoms.
Delineate the extent of host involvement
Primary Infection - Acute infection caused by initial illness.
Secondary infection - Caused by opportunistic microbe after host immune system weakened by primary infection.
Subclinical infection - Does not noticeable disease.
What are the stages of disease development?
1: Incubation period - no signs or symptoms
2: Prodromal period - mild signs or symptoms
3: Illness - Death can result if immune responses and/or medical treatments fail
4: Period of Decline
5: Period of Convalescence (mild to no symptoms.(Recuperation)
What are the three routes of disease transmission
Contact: Direct, Indirect, Droplet
Vehicle - Non- living
Vectors
What are the three main routes of disease transmission
- Contact: Direct, Indirect, Droplet
- Vehicle - Non living object that transmits disease causing pathogen.
- Vectors -
What routes do microbes use to exit host
Respiratory tract: Via cough/sneeze
GIT: Via faeces
Urogenital: Via vaginal/penile secretions
Skin: Via open wounds
Blood: Open wounds, Surgery, Syringes
What are nosocomial infections and what proportion of patients acquire them?
Infection acquired during the course of stay in a hospital, nursing home, or other health care facility.
5-15% of patients
What type of organisms are implicated in nosocomial infections
Gram negative opportunistic drug resistant bacteria often involved - Pseudomonas spp
What are the three types of reservoirs for infection
Human, Animal and non-living
