Disease-Causes, Determinants, Transmission (7) Flashcards
What is the epidemiological triad?
agent, host, environment
encompasses disease (disease potential)
What are agents?
things that cause disease
all may have varying inherent factors influencing their ability to cause disease
What are agent factors?
infectivity
pathogenicity
virulence
immunogenicity
antigenic state
survival
What is the disease spectrum?
What is infectivity?
a measure of the ability of a disease agent to establish itself in the host
- usually referred to qualitatively (low, medium, high)
agent factors
What is pathogenicity?
used to describe the ability of a particular disease agent of known virulence to produce disease in a range of hosts under a range of environmental conditions
What is virulence?
a measure of the severity of a disease caused by a specific agent
What are host factors?
species
breed
sex
age
conformation
genotype
nutrition status
physiologic status
pathologic status
What is the most common inherited bleeding disorder in dogs? What does this show?
hemophilia A (Factor VII deficiency)
females carry the gene for the disease without showing any signs
host factor
What are environment factors?
What are Koch’s postulates for infectious diseases?
- the agent should be present in all cases of the disease
- it can be isolated and grown in pure culture
- it should be capable of producing the disease when inoculated into healthy animals
- the same organism should be recovered from the diseased animal
What are limitations of koch’s postulates?
- do not apply for inapparent infections or carrier states
- some organisms are tough to grow in pure culture
- rarely apply to viral infections/diseases
- do not apply to multi-factorial etiologies
What are modes of transmission?
direct contact
indirect contact
What is direct transmission?
the physical contact between an infected individual and a susceptible individual, and the physical transfer of microorganisms
What are direct transmission - airborne?
What is direct transmission - droplet?
What is indirect transmission - fomites?
refers to situations where a susceptible person is infected from contact with a contaminated surface or material
T/F: Foodborne transmission is direct
FALSE - indirect
What is indirect transmission?
vector borne - transmission via insect or animal vector
What is an example of multiple transmission modes?
What is the goal of herd/public health?
STOP disease transmission
What is zoonosis?
any disease or infection that is naturally transmissible between vertebrate animals and humans
sounds the exact same as zoonotic disease
