Ch. 14 - Principles of Disease and Epidemiology Flashcards
Define: Pathology
the study of disease; relationship between pathogen and host
Define: Etiology
the study of the cause (origin) of a disease; involved in naming of pathogen
Define: Pathogenesis
the development of disease (a process)
Define: Infection
invasion or colonization (attachment) of the body by pathogens
Define: Disease
an abnormal state in which the body is not performing normal function
TWO TYPES:
infectious disease: caused by pathogen
non-infectious disease: not cause by pathogen (ex: cancer, diabetes)
Define/know key differences between normal microbiota and transient microbiota
Normal microbiota: microbes that are always present in/on the human host; cause no harm if they remain in a certain area
Transient microbiota: microbes that take up temporary residence and remain in the body for only hours to months
Where in/on the human body would you expect to find transient microbiota?
skin, because transient microbiota take up temporary residence and skin sheds often
Define: Symbiosis
relationship between microbe and the host
What are the “3 types” of symbiosis?
Define them and include examples
Commensalism (Normal Microbiota)
- one organism benefits and the other is unaffected (host doesnt benefit)
- Staphylococcus epidermidis (human provides home)
Mutalism (Normal Microbiota)
- both organisms benefits
- E. coli (make vit. K)
Parasitism
- one organism benefits at the expense of the other
- Influenza virus
Define/Describe Koch’s: Germ Theory of Disease
a specific pathogen is capable of causing a specific infectious disease that is associated with specific symptoms
Define: Kochs Postulates
Four criteria designed to establish a causasive relationship between a microbe and a disease
Explain, in correct sequence, all four of Kochs Postulates. What was the objective/purpose of Koch’s Postulates?
- The SAME pathogen must be PRESENT in every case of the disease
- The pathogen must be ISOLATED from the DISEASED HOST and GROWN in pure culture
- The pathogen from the pure culture MUST CAUSE the disease (and same symptoms) when its inoculated into a HEALTHY HOST (labratory animal)
- The pathogen must be ISOLATED from the inoculated animal and must be shown to be the ORIGINAL ORGANISM
PURPOSE: to determine the cause of an infectious disease (specific pathogen causes a specific disease)
What are the exceptiosn to Kochs postulates?
- some pathogens can cause severase disease conditions
-> Streptococcus Pyogens can case Scarlet Fever and Strep Throat - some pathogens cause disease only in humans (would need to use human subject instead of lab rats)
- some microbes cannot grow on artificial media
Define: Symptoms
Include examples
- changes in body function that are felt by a patient (not observed/measured)
- ex: pain, fatigue
Classifying Infectious Diseases
Define: Signs
Include examples
- changes in a body that CAN be measured or observed
- ex: temperature, weight, blood pressure
Classifying Infectious Diseases
Define: Syndrome
Include examples
- a specific group of signs and symptoms that accompany a disease
- ex: Down syndrome, AIDS
Classifying Infectious Diseases
Define: Communicable Disease
Include examples
- a disease that is spread from one host to another
- Contagious disease: disease that is easily and rapidly spread
- ex: chickenpox (airborne)
Classifying Infectious Diseases
Define: Noncommunicable Disease
Include examples
- a disease that is NOT spread from one host to another
- ex: tetanus; diabetes
Classifying Infectious Diseases
Define: Incidence
- number of people who develop a disease during a specific time period
Occurance of a Disease
Define: Prevalence
- number of people who develop a disease at a certain time, regardless of when it dirst appeared; takes into account both old and new cases
- indicates how widespread the disease is
Occurance of a Disease
Which one of these terms (incidence or prevalence) refers to a larger time period?
prevalence
Define: Sporadic Disease
Include examples
- disease that occurs only occassionaly; randomly
- ex: Mad Cow Disease (prions)
Occurance of a Disease
Define: Endemic Disease
Include examples
- disease constantly present in a population
- ex: Malaria (along the equator)
Occurance of a Disease
Define: Epidemic Disease (“Outbreak”)
Include examples
- disease acquired by many people in a given area in a short time; spreads quickly
- ex: Influenza
Occurance of a Disease
Define: Pandemic Disease
Include examples
- worldwide epidemic; global scale
- ex: COVID-19; AIDS
Occurance of a Disease
Define: Acute Disease
Include examples
- symtoms develop rapidly but the disease lasts only a short time
- ex: Influenza
Severity/Duration of a Disease
Define: Chronic/Persistant Disease
Include examples
- symptoms develop slowly and last long time
- ex: TB (tuberculosis)
Severity/Duration of a Disease
Define: Subacute Disease
- intermediate between acute and chronic disease
Severity/Duration of a Disease
Define: Latent Disease
Include examples
- pathogen is inactive for a time, but then activates and produces symptoms (bc pathogen become dormant/hide in body)
- ex: Shingles
Severity/Duration of a Disease
Define: Herd Immunity
- immunity where entire population is protected
- accomplished through vaccinations
How is Herd Immunity accomplished?
Include examples
- if most of the population gets immunized, then the entire population is protected (include the healthy, non-immunized)
- ex: chickenpox, measles
Define: Local Infection
Include examples
- pathogens are limited to small area of the body; doesn’t spread
- ex: skin infection
Extent of Host Involvement
Define: Systemic (Generalized) Infection
- infection throughout the body (bc pathogen spread through blood stream)
Extent of Host Involvement
Which type of infection is worse: Local Infection or Systemic Infection
Systemic Infection
Define: Sepsis/Septicemia
uncontrollable spread of pathogen in the blood = life threatening condition
Type of Systemic Infections
What are the different types of Sepsis/Septecemia?
Define them
Bacteremia: bacteria in blood
Toxemia: toxins in blood
Viremia: viruses in blood
Types of Systemic Infections
Define: Primary Infection
Include examples
- acute infection that causes the inital illness
- ex: HIV/AIDS (due to HIV virus)
Extent of Host Involvement
Define:Secondary Infection
Include examples
- caused by opportunistic pathogens (ex: fungal infection in lung) after a primary infection
- ex: AIDS-related opportunistic infections = death
Define: Predisposing Factors
factors that make the body more susceptible to disease
Name all the examples of Predisposing Factors and give an example of who/what is more susceptible
GAPLIC
- Gender
-> female: ovarian cancer
-> male: prostate cancer
- Age
-> elderly: shingles
- Poor sanitary conditions
-> parasitic worm infections
- Lifestyle
-> intravenous drug users: bacteremia
- Inherited Traits
-> diabetes
-Climate and Weather
-> warm/tropical: malaria
Identify on a graph, the 6 stages of disease and be able to describe key evenets occuring during each stage
check slide 20 on Ch. 14 for graph
1. Incubation Period
- no signs and symptoms present, but pathogen is growing; interval between inital infection (youre infectious) and first signs and symtoms
2. Prodromal Period
- first appearance of signs and symptoms
- early, mild SXS; short period after incubation
3. Period of Illness
- Most severe signs and symptoms; start producing Ab
4. Peak of Illness
- highest number of microbes present and will lead to either: Period of Decline or Death
-> Ab titer the highest
5. Period of Decline
- Signs and symptoms subside/decrease
6. Period of Convalescence/Recovery
- Body returns to its pre-diseased state
-> Pathogen leaves the body and host feels betters, but is still highly infectious. Host is considered asymptomatic/chronic carrier
Define: Reservoirs of Infection
continual sources of infection (location of pathogen)
Name and Describe the three categories of reservoirs.
Human Reservoir
- sick people or “carriers” that have no signs or SXS
Animal Reservoir
- Zoonoses: ability to transmit pathogen from animal to huamns (zoonotic transmission)
-> ex: Bird Flu
Non-living Reservoir
- contaminanted inanimate (nonliving) objects
-> ex: contaminated soil, air, water, food
Define: Transmission of Disease
pathogens from reservoirs of infection can be transmitted to a susceptible host
List the 3 principle routes of disease transmission
Contact Transmission
Vehicle Transmission
Vector Transmission
Name and describe the different types of Contact Transmission
Direct Contact Transmission
- requires touching between infected person and suceptible host
-> ex: shaking hands
Indirect Contact Transmission
- spreads to host by contaminated non-living objectes, called fomite
-> ex: contaminated doorknob, utensils
Droplet Transmission
- transmission via airborn droplets LESS than 1 meter
Define: Vehicle Transmission
Name and describe the dirrerent types of vehicle transmissions
Vehicle Transmission: transmission by contaminated inanimate reservoir
-> Airborne
- transmission via airborne droplets MORE than 1 meter
-> Waterborne
-> Foodborne
Define: Vector Transmission
(ex: How is it accomplished)
Name and describe the different types of vector transmission
Vector Transmission: accomplished by arthropods (living animal)
-> ex: fleas, ticks, mosquitos (have pathogen in/on them)
Arthropods transmit disease by two general methods:
Mechanical Vector Transmission
- arthropod vector carries pathogen outside (on) its body
- called “passive transport” of pathogen
-> ex: pathogen on foot of fly
Biological Vector Transmission
- athropod vector varries pathogen inside (in) its body
- called “active transport” of pathogen
-> pathogen transmitted via bites
What is a HAI?
Heathcare-Associated Infections
- an infection acquired in the hospital/clinic cenvironment
-> affects 1in 25 hospital patients
-> 1.7 million/year infected; 99,000+ deaths
List the 3 major common causes of HAIs
- improperly cleaned healthcare setings
- weakened immune status of host
- trasmission of pathogens
What is the major site of HIAs in the human body? What are some other common HAIs?
Contaminated equipment
- Surgical-site infections (22%)
- Pneumonia (LRT infection; 22%)
- C. Difficile infections (Gastrointestinatl infection, 17%)
Name the bacterium responsible for the greatest percentage of infections involving HAIs
Surgical Related Bacteria
- Staphylococcus Aureus (16%)
- Clostridium Difficile (15%)
Define: Epidemiology
the study of when and where diseases occur and how they are transmitted in populations (studying population affected by DZ)
What is the purpose of the CDC?
CDC = Center for Disease Control and Prevention
- collected and analyzed epidemiological information in the US
Compare and Contraste Morbidity and Mortality
Morbitidy: number of people/incidence of a notifiable disease (number of sick people)
Mortality: number of deaths from notifiable diseases
What is a Nationally Notifiable Infectious Disease?
List 3 STD examples that are nationally notifiable diseases
Nationally Notifiable Infectious Disease
- disease where physicians are required, by law, to report occurance to CDC
-> Includes any STD
-» HIV infection
-» Gonorrhea
-» Syphillis
Define: Compromised Host
a host with a weakened immune system
