Epidemiology : Dynamics Of Disease Transmission Flashcards
What is a communicable disease
-Illness due to specific biological agent or its toxic product capable of direct or indirect transmission from man to man , animal to man , or from
Environment to man
What is an infection
- entry and multiplication from an infectious agent in the body of man or animal
- does not always cause disease
Gradient / Levels infection
1 colonization
2 sub clinical ie inapparent infection
3 latent infection
4 clinical infection
What is latent, sub clinical and clinical infection
- infectious agent present in body but not causing any overt symptoms. Patient is still infected and can pass on to others
- no detectable signs. Patient is asymptotic
- a stage in pathological condition where infectious agent causes anatomical or physiological changes sufficient to be recognized as signs and symptoms
What is contamination
-presence of an infectious agent on a body surface clothes beddings toys surgical instruments or substances including water and food or soil
What is infestation
-lodgment or development and reproduction of arthropods on body surface or clothes and bed lining
Ascariasis
-invasion of gut by parasitic worms
What is a contagious disease
-disease transmission through contact
What is opportunistic infection
-infection by organism that take opportunity provided by a defect in host defense to enter multiply and cause disease
Nosocomial infections
-hospital acquired
- infection originating in patient while in hospital or other health Care facility
- new disorder has to be unrelated to patients primary condition
List Host conditions
- biological characteristics
- behavioral
- demographic
- socioeconomic
List types of agents
- biological
- chemical
- physical
- nutritional
List types of environments leading to disease
- social
- physical
- biological
What is virulence of agent
What is case fatality rate for infectious disease
- degree of pathogenicity
- disease evoking power of micro organism and in a given host
- numerically is ratio of # of overt cases TO # of total infections
- shows severity of infection
- ratio of infected and died TO # of total infection
What is a host and susceptible host
- a person or animal that affords subsistence or lodgment to an infectious agent under natural conditions
- more likely to succumb to infectious agent so that it can easily achieve parasitism
4 stages of parasitism
1 portal entry
2 lodgment or development inside host
3 portal of exit
4 survival in external environment
What is source of disease
- starting point for the occurrence of a communicable disease
- can be place, person, animal or object from which infectious agent is disseminated to susceptible hosts
What is special host : reservoir
- natural habitat for infectious agents
- any person, place, or animal or combination of these in which infectious agent normally lives , depends primarily on for survival and where it’s reproduces in such a manner it can be transmitted to susceptible host
What is incubation and latent period
- time from exposure to appearance of first signs of disease
- time from exposure to shedding ( onset of infectiousness )
What is a disease
- a particular abnormal condition that negatively affects the function of part or all of an organism not caused by external injury and is associated with specific signs and symptoms
- caused by external pathogen or internal dysfunction
What is a case
-person in population or study group identified as having a particular disease, disorder disorder or condition under investigation
What is a carrier
- infected person or animal that harbors specific agent but without any discernible clinical disease
- serve as source of infection to others
3 elements needed to form a carrier
- disease present in body
- absence of recognizable signs
- shedding of disease in discharge
What causes formation of carrier
-inadequate treatment or immune response and agent not completely eliminated leading to carrier state
Describe animal reservoirs and zoonosis
-zoonosis are infectious transmissible under natural conditions from vertebrae animals to people
What is a vector
-an insect or living carrier that transports that transports infectious agents from other infected hosts, from its food , waste or immediate surroundings to non/infected susceptible host
Non living reservoirs
-soil and inanimate objects can also serve as reservoirs for infections
Type of carriers
1 incubatory
2 healthy
3 convalescent ( recovering )
Exit portals via carriers
- urinary
- respiratory
- intestinal
Duration of carrier state
- chronic
- temporary
Types of cases
1 clinical ( mild / severe-typical / atypical )
2 sub clinical
3 latent
Levels of cases and describe
1 index - patient zero. 1st documented patient within a population of a condition or syndrome
2 primary case - infectious disease that spread from human to human and refers to person who 1st brings disease into a group of people
3 secondary case - occurring of disease due to close contacts of a primary case patient 24 hours after onset of illness in primary case
