Epidemiology Flashcards
What is the crude death rate?
number deaths/people at risk of dying
What is the age adjusted death rate?
deaths/100K
What does age adjusted rate allow you to compare?
Allows comparison between geographic areas with different proportions of older people who are more likely to die of infectious (or any) diseases
What is the age specific rate?
# deaths (age group x)/
# people (age group x) at
risk of dyingWhat is proportional mortality?
# deaths due to cause x, time t/
# All deaths during same timeWhat is the case fatality rate? When is this measure useful?
tells the number of people who die who get the disease
gives you info about how virulent it is…not necessarily which disease requires the most resources.
What are the steps involved in an outbreak investigation?
- verify the existence of an outbreak
- confirm the diagnosis
- Assemble the team.
- Develop a case definition.
- Count person, place, time
- Communicate Findings
- introduce preliminary control measures
- Design study to test hypothesis
- Form a hypothesis
- surveillance & monitoring
What are the top 10 leading causes of death in 2013?
Heart disease Cancer Lung Dz Stroke Injury Alzheimer's Diabetes Nephritis.. P&I Suicide
What are the top 10 leading causes of death in 1900?
P&I TB Diarrhea&Enteritis Heart Dz Stroke Liver Dz Injuries Cancer Senility Diptheria
T/F The case definition changes as you learn more about the outbreak.
True.
According to a case definition, what makes for a confirmed case?
laboratory confirmed diagnostic evidence of a viral infection etc.
What makes for a probable case?
a PUI (person under investigation) who has symptoms of the disease, or has come in contact with the disease.
What is the name of a curve that shows count (sorta a bar graph) & describes it in terms of person, place, time?
epidemiological curve
T/F case fatality rate can change by population.
True. Maybe this is a population that doesn’t seek medical care.
T/F An incubation period can be estimated from an epidemiological curve.
True.
What does a point source show?
a common source of outbreaks
What is the incubation period of chickenpox?
10-21 days
What is the incubation period of rabies?
1-3 mo
What is the incubation period of influenza?
up to 7 days
What is the incubation period of measles?
about 10 days
What is the incubation period of mumps?
about 17 days
What is the incubation period of rubella?
14-21 days
What is the incubation period of tetanus?
4-21 days
What is the incubation period of whooping cough?
7-10 days
What is an attack rate?
a specific type of incidence rate; calculated for a narrow population. # new cases among pop during the period X 100/pop. at risk at the beginning of the period **measures the probability of risk of becoming a case
When is the attack rate useful?
useful if the course of the current outbreak is similar to other outbreaks
useful to examine vulnerable subgroups
What is the secondary attack rate? What is this useful for?
# cases among contacts of primary cases during period X100/ total number of contacts **important for diseases transmitted person to person (TB measles etc)
What is the natural history of disease?
unchecked progression of the disease in an individual
What are some examples of natural history of disease?
tuskegee
typhoid mary
screening
What is the timeline of the natural history of disease?
stage of susceptibility
exposure
stage of subclinical disease w/ pathologic changes
onset of symptoms
stage of clinical disease (usu time of diagnosis)
stage of recovery, disability or death
What is eradication?
Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent; intervention measures are no longer no longer needed.
What is extinction?
The specific infectious agent no longer exists in nature or the laboratory
What are 6 common reasons for vaccine distrust?
- Hygiene & sanitation (not vaccines) is what caused incidence of disease to be lowered.
- The majority of people who get disease have been vaccinated.
- Hot lots
- Vaccines have unknown long-term side effects.
- Country doesn’t have vaccine-able diseases. I don’t need a vaccine!
- Giving a child multiple vaccinations could overload their immune system.
Which disease is eradicated? Which is almost eliminated? Which is eliminated in Finland?
Eradicated-smallpox
Almost Eliminated–Polio
Eliminated in Finland–Measles
Diphtheria, mumps, rubella, pertussis, Hib what is their status?
well controlled in developed countries
What are 2 diseases that are NOT controlled?
chickenpox
perovirus
What are 2 diseases that are selectively controlled?
Hep B
BCG
T/F There is an animal reservoir of smallpox.
FALSE. Good for its eradication.
T/F Measles could theoretically be eradicated.
True. No animal reservoir & an effective vaccine.
What are 5 possible benefits of modeling infectious disease?
- Gain insight into mechanisms influencing disease spread, and link individual scale ‘clinical’ knowledge with population-scale patterns.
- Focus thinking: model formulation forces clear statement of assumptions, hypotheses.
- Derive new insights and hypotheses from mathematical analysis or simulation.
- Establish relative importance of different processes and parameters, to focus research or management effort.
- Explore management options.
What is the SEIR framework?
S: susceptible
E: exposed
I: infectious–able to transmit pathogen
R: removed–immune or dead individuals
What does lambda stand for in the SEIR framework? Which transition does it represent?
lambda-force of infection
transitions from susceptible to exposed
What does v represent in the SEIR framework? Which transition does it represent?
rate of progression to infectious state=1/latent period
**exposed to infectious
What does gamma represent in the SEIR framework? Which transition does it represent?
rate of recovery=1/infectious period
**transition from infectious to removed
What is Ro? What does it mean if Ro1?
Ro is basic reproductive number.
Ro1: disease can invade
**Expected number of cases caused by a typical infectious individual in a susceptible population
How is Ro calculated?
Ro=CPD
What is C?
C = the number of contacts the infectious person makes per unit time (day, week, month, etc.)
What is P?
P = the probability of transmission per contact with the infectious person
What is D?
D = the duration that the infected person is infectious to others
How is R different from Ro?
R is the effective reproductive number
this is the average number of secondary infections produced by a typical infective index case
In a homogenously mixing pop. how does R relate to Ro?
R=RoS (S is the proportion susceptible to infection)
If R>1 what does this mean? If R<1 what does this mean? If R=1 what does this mean?
R=1 is equilibrium.
R1: moving toward epidemic
We need Reffective to be less than 1 to have herd immunity. What is the equation that represents this?
Reff=Ro XS/N
What is herd immunity?
Percentage of individuals in a population who need to be immunised in order to achieve herd immunity varies and depends on such factors as the effectiveness of the vaccine and characteristics of the disease
For a child who is immunosuppressed in a community, how can they be protected from a disease?
Herd immunity! Everyone around them is vaccinated.
