L7: Epidemiology Flashcards
The epidemiologic triad is a pattern of interaction between: ____, _____, and ____
1) susceptible HOST
2) agent
3) environment
True or False: Getting a microbe via kissing or interacting with in animal is a type of direct contact
True
What’s the difference between a biological and mechanical vector?
Biological vector: involves part of the pathogen lifecycle ; transmission via saliva or feces
Mechanical vector: passive transport of a pathogen on a vector’s body
True or False: The chain of transmission is: source for agent => portal of exit => mode of transmission => portal of entry
True
A continual source of infection is called a ____ of infection
reservoir
Human reservoirs are people who…..
1) have a disease
2) carry a pathogenic microorganism
____ are disease that affect wild and domestic animals and can be transmitted to humans
Zoonoses
True or False: Soil can be a non-living reservoir of C. botulinum, C. tetani, or fungi
True
True or False: Improperly prepared or stored foods can be nonliving reservoirs
True
Respiratory route, saliva, GI, skin to skin, blood-borne are examples of:
A. Vertical Spread
B. Horizontal Spread
B. Horizontal Spread
What is the most common and most difficult to control form of horizontal transmission?
Respiratory route
In the respiratory route of horizontal transmission, the ___ is equal to the ___
Po exit = Po entry
True or False: The larger a droplet nuclei (respiratory secretion or droplet), the longer it remains suspended in the air for longer than 20 minutes and can penetrate and attach to upper/lower respiratory tract
False - the SMALLER droplets remain suspended in the air for ~20 minutes
Which type of infectious disease is not transmitted (or at least not routinely transmitted) from person to person?
Non-communicable infectious disease
How can a non-communicable disease arise from one’s normal flora?
Aspiration of normal flora can lead to pneumonia
Provide an example of an environmental pathogens that can cause a non-communicable disease.
Provide an example of a zoonoses that can cause a non-communicable disease.
Environmental = Tetanus
Zoonoses = Rabies
Communicable disease are those transmissible from person to person. What are the three routes by which a disease can be spread person to person? Which is the most common?
1) Horizontal Spread - most common!
2) Vertical Spread
3) Zoonotic Spread
Which four conditions can be spread via salivary horizontal transmission?
EBV
Oral/genital herpes
CMV
Rabies
What are two horizontal routes by which GI pathogens can spread?
1) Fecal-oral route
2) Aerosolized vomitus
Which two microbes can be horizontally transmitted via: aerosolized vomitus?
H. pylori
Norovirus
True or False: Compromised skin allows for more pathogen access
True
True or False: Staph and Strep can be transmitted via: skin to skin contact
True
True or False: Herpes, HPV, and Dematophytoses can be transmitted via skin to skin contact
True
Which two conditions are anthropod-borne (blood borne)?
Lyme disease (tick = vector)
Malaria (mosquito = vector)
Which two pathogens can be transmitted from human to human via BOTH blood and body fluids?
1) Hep B/C
2) HIV
Which mode of horizontal transmission is helminth (pin worm) typically acquired via?
A. Eye to Eye
B. Fomites
C. Genital
D. Autoinoculation
D. Autoinoculation
HIV and CMV can be transmitted to a child via vertical transmission during:
A. transplacentally
B. parturition
C. breastfeeding
C. breastfeeding
Gonococcal conjunctivitis and Strep B can be transmitted to a child via vertical transmission during:
A. transplacentally
B. parturition
C. breastfeeding
B. parturition
True or False: HIV can be passed to child transplacentally
False - rubella virus can be transmitted this way
___: infections spread from their natural reservoirs (often mammalian) to humans
Zoonosis
True or False: Zoonosis can occur via direct transmission or through a vector
True
- Direct transmission (rabies)
- Vector (tick/lyme)
Human to human spread from an initial zoonotic index can also occur, as in the case of ____
pneumonic plague
____: the indirect effect of protection from infection of otherwise susceptible members of the population and, by extension, population as a whole as a result of presence of immune people
Herd Immunity
True or False: Sufficient herd immunity can be a firewall to spread of an infection
True
What three factors affect herd immunity?
1) Speed of spread - attack rate
2) Host Factors - past exposure? immunized?
3) Environment - hygiene
What are three examples of immunity leading to herd immunity?
- Mumps
- Measles
- Pertussis
- Both of the first two had high attack rates
Which type of epidemic indicates: person to person spread or communicable disease?
Propagating epidemic
What’s the difference between a sporatic and pandemic?
Sporadic is ocassional cases at irregular intervals in random locations
Pandemic is global
_____: epidemic and endemic zoonoses, respectively
Epizootic and enzootic
Which period of disease is critical for building a differential diagnoses and rule in/out potential sources of infection?
Incubation period
What is a benefit of prolonged incubation periods?
Offers the opportunity for immunoprophylaxis or chemoprophylaxis (rabies, tetanus)
_____: defined as the time between exposure to a pathogen and the appearance of the first signs and symptoms of disease
Incubation period
___ has an incubation period of 1-2 days while _____ has an incubation period of 7-15 years
A. Norovirus
B. Rubella
C. Creutzfeldt-Jakob
Norovirus; Creutzfeldt-Jakob
How does a higher inoculation dose affect the length of the incubation period?
Higher dose means shorter IP
How does a faster replication time of an organism affect the length of the incubation period?
Fast replication means shorter IP
If the site of inoculation is closer to the target tissue, the incubation periods will be ____
shorter
Diseases are classified by ___ of occurence
frequency
_____ are important considerations in build a differential diagnosis for an infectious disease. Also helps to identify populations at risk.
Risk factors
_____: the occurrence of new cases during the time period being examined
A. Morbidity
B. Mortality rate
C. Prevalence/Point prevalence
D. Incidence/Incidence Rate
D. Incidence/Incidence Rate
True or False: As incidence increases, so does the probability of getting the disease
True
True or False: Incidence can increased within certain seasons
True
____: total number of cases (old and new) in a population in a defined period
A. morbidity
B. mortality rate
C. prevalence
C. prevalence
____: total # of deaths in a population due to given disease
____: total # of persons afflicted with infectious disease
Mortality Rate
Morbidity
Which disease show prevalence (2001) and seasonality (summer)?
Lyme
_____: the presence of (or rate of) an infection or disease in a population - a constant
Endemic/endemicity/endemic rate
____: a statistically significant increase above the endemic rate of a disease
Epidemic
What are the three type of epidemics?
1) Common source
2) Point source
3) Progressive/propagative
