Chapter 12: Epidemiology of Infectious Diseases Flashcards
What does the 3 factor epidemiologic triangle consist of?
- Agent
- Host
- Environment
What is an agent?
a factor that must be present for an infection to occur
What are characteristics of infectious disease agents?
- infectivity (Ingrid)
- pathogenicity (Payton)
- virulence (Victoria)
- toxigenicity (Toni)
- resistance (Renee)
- antigenicity (Anne)
Antigenicity?
the ability of the agent to induce antibody production in the host
Host?
the person or animal who is capable of developing an infection following exposure to an agent
immunity?
concerns the resistance of the host to a disease agent. can be either passive/active or natural/artificial
active immunity?
when exposure to a disease organism triggers the immune system to produce antibodies to that disease
- long lasting but takes time to develop
- Alex and Imogen were at the race line ready to start. As soo as they both heard the gunshot, it triggered them to begin running
passive immunity?
when a person is given antibodies to a disease rather than producing them through their own immune system
natural active immunity?
results from an infection by the agent; someone is exposed to a live pathogen, develops the disease, and becomes immune
artificial active immunity? (vaccine induced immunity)
results from an injection with a vaccine that stimulates antibody production in the host. the person can build resistance to a disease following an immunization
natural passive immunity?
Preformed antibodies during pregnancy are transferred across the placenta to the fetal bloodstream to produce short-term immunity in the newborn. immunity from mother to child
artificial passive immunity?
Preformed antibodies against a specific disease are administered to an exposed individual to confer protection against a disease. injected antibodies created w/in a different person or animal
What is the environment?
the domain where the disease causing agent may exist, survive, or originate. In some instances, it serves as a
reservoir or niche that fosters the survival of infectious disease agents
Modes of transmission? (of diseases)
- airborne
- droplet
- direct contact
- vehicle (food, etc.)
- vector (insects, animals, etc.)
direct transmission of diseases?
the spread of infection through physical (person to person) contact
-sexually transmitted (touching,kissing,sex, etc)
indirect transmission?
the spread of an infection though an intermediary source: vehicles, vectors, and fomites
vehicle spread?
a method for transmitting an infectious disease agent. spread by food, water, air, etc.
what is a vehicle?
the medium that contains the agent
Ex: water, food, infected blood
what is a fomite?
an inanimate object laden w/ disease causing agents
Ex: doorknob, clothing, etc.
what is a vector?
an animate, living insect or animal involved w/ transmission of the disease agent
portals of exit?
sites where infectious agents may leave the body. includes respiratory passages, the alimentary canal, the genitourinary openings, and skin lesions
What is an inapparent (subclinical) infection?
one that hasn’t penetrated the clinical horizon. it diesn’t have clinically obvious symptoms.
Incubation period?
the time interval between exposure to an infectious agent and the appearance of the first signs or symptoms of disease
Herd immunity?
the immunity of a pop., group, or community against an infectious agent when a large proportion of individuals are immune. Happens when immune people prevent the spread of a disease to unimmunized people
Generation time?
the time interval between lodgment of an infectious agent in a host and the maximal communicability of the host
Colonization?
the multiplication of an infectious agent on the surface of the body w/o invoking a tissue or immune response
Infestation?
the presence of a living infectious agent on the body’s exterior, on which a local reaction may appear
iceberg concept of infection?
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secondary attack rate?
measure the spread of a disease w/in a household or similar circumscribed unit. pertains to the spread of disease in a family, household, dwelling unit, dormitory, or similar circumscribed group.
case fatality rate? (CFR)
a proportion formed by the # of deaths caused by a disease among those who had a the disease; expressed as a percentage
basic reproductive rate (R0)?
a measure of the # of infections made on average by by an infected individual in the early stages of an epidemic when all contacts are susceptible
Virulence?
an agent’s capacity to induce disease in the host
Infectivity?
the capacity of the agent to enter and multiply in a susceptible host and thus produce infection or disease.
Pathogenicity?
concerns the capacity of the agent to cause overt disease in the infected host
Toxigenicity?
denotes the capacity of the agent to produce a toxin or poison
Resistance?
signifies the ability of the agent to survive adverse environmental conditions
Cholera is another example of what kind of disease?
a water or foodborne disease; an acute enteric disease w/ sudden onset, occasional vomiting, rapid dehydration, acidosis, and circulatory collapse
What are STDs or STIs?
Sexually transmitted disease/infections. Diseases spread by sexual activity or sexual intercourse
What are the 3 stages of HIV?
- acute
- chronic
- AIDS
Vaccine preventable diseases?
infectious diseases that vaccinations can aid in controlling -Measles Chicken pox -Hepatitus A/B -Pertusis
What is zoonosis?
a disease that, under natural conditions, can be spread from vertebrate animals to humans.
Arboviral diseases?
diverse group of diseases that involve transmission of arboviruses
emerging/re-emerging infections?
infectious diseases that have been identified or have come back
