Basic concepts of diseases Flashcards
(54 cards)
what is disease?
harmful deviation from the normal structure or functional state of an organism
epidemiology
study of incidence, distribution, and control of disease in a population
pathology
the science of the causes and effects of diseases
pathogenesis
the development of the disease and the chain of events leading to that disease
koch’s postulates
- the agent is present in every case of the disease
- the agent must be isolated from a diseased animal
- the cultured microorganism should cause the disease when introduced into a healthy animal
agent (examples)
only have to know a few
- toxicity
- dose
- pathogenicity: ability to cause disease
- infectivity: ability to infect
- immunogenicity: ability to provide immune response
- antigenic stability: agent is stable in environment long enough
- survival: does it cause death too quickly to be passed on
environment (examples)
- weather
- housing
- management
- geography
- air quality
- nutrition
- stock density
- animal movement between groups
host factors (examples)
- age
- sex
- genotype
- behavior
- nutritional status
- health status
- stress status
- reproductive status
- immune status
- innate resistance
steps during “disease” development in an animal
- exposure
- incubation
- prodromal
- decline
- convalescence
asymptomatic
no symptoms
latent
symptoms appear a long time after initial development
clinical
symptoms are present
incubation period
interval from exposure to clinical symptoms
carrier status
usually no clinical symptoms but can transmit infection for long periods
communicable (contagious, transmissible, infectious)
spread from one animal to another
non-communicable
arises from outside of hosts or from opportunistic pathogen
clinical sign (important)
something that somebody else can see, based upon physical findings
symptom (important)
the subjective experience of the patient
ex: the owner believes of what the symptoms are of their animal (animals don’t talk)
lesion
area of tissue with an abnormal structure or function
susceptible
animal at risk of developing a disease, if exposed to the agent
reservior
a long-term natural host for a disease that serves as the source of infection for other hosts
ex: a group of animals who live in that region
- Yellowstone bison can infect cattle
vector
- intermediate carrier of the disease to susceptible animals without showing symptoms of disease
- “individual”
ex: mosquito gave disease to dog
local disease
confined to a small region of the body
systematic disease
widespread disease in multiple systems of the body
