Epidemiology Flashcards
Epidemiology definition
Study of Distribution of determinants of health related states or events in specified populations and the application of the study to control health problems
Five questions to ask yourself in epidemiology
who has the health condition where is the health condition found when does the health condition occur why does the health condition exists how can Health condition be prevented
Three questions to ask yourself in disease specific epidemiology
What causes the disease
how is the disease transmitted
how do we break the transmission cycle
Objectives of epidemiology
Identify cause of health condition
determine extent of health condition in a community
study the natural history and prognosis of health condition
evaluate existing and newly developed preventive and therapeutic measures
provide foundation for public policy
Top 10 causes of death in Ghana
Malaria lower respiratory infection neonatal disorders ischemic heart disease Stroke HIV aids tuberculosis diarrheal diseases roads injuries diabetes
The five major cause of death in Ghana in children
Malaria diarrheal diseases respiratory infections anemia malnutrition
Type of prevention
primordial prevention
primary prevention
secondary prevention
tertiary prevention
Primordial prevention
You prevent occurrence of risk factors
Primary prevention
You prevent initial development of a disease
Secondary Prevention
You detect early existing disease to reduce severity and complications
Factors involved in interaction to form disease
Hosts
agents
environment
Host characteristics that could lead to disease formation
Age sex religion Occupation marital status genetic profile immune status
Type of agent that could lead to disease fornation
Biological agents
chemical agents
physical agents n
nutritional agents
Environmental factors that could lead to disease formation
Housing crowding neighborhood water source toilet facilities
Transmission
Mechanism by which an infectious agents is transferred from one person to another OR from one Reservoir to a new host
Type of mode of transmission
Direct indirect intermediate host vectors zoonosis
Direct transmission
From human to human or auto infection
Indirect transmission
From single, multiple, or continuous exposure to one common vehicle
Intermediate host transmission
Transmission from snails, copepods,animals, worms
Vector transmission
From an insect to man
Zoonotic Transmission
Animal disease now presents in man
Transmissible by bites or food
How can a host resist to a disease
Through acquired immunity like infection vaccination or passive immunity from mother to child
Factors that can Impact the hosts immunity
Age sex pregnancy nutrition trauma fatigue herd immunity
Type of environment
Physical
biological
social
Physical environments
Nonliving part like air water soil temperature
Biological environment
Living things like plants animals micro organisms
Social environment
Man-made lake community culture government
Factors that can affect environment
Climate like temperature
seasonality which includes interaction of climate food culture
education with knowledge that can cause modified behaviors
resources like poverty
Susceptibility to disease
Measure of a person risk of acquiring a disease
Factors that determine susceptibility to disease
Genetics
nutrition
immune system
Stages of disease
Preclinical
subclinical
persistent disease
latent disease
Clinical disease
Disease with signs and symptoms
Carrier status is
Individual has disease organism but is not infected as measured by serological studies or by evidence of clinical illness
Levels of disease
Sporadic endemic hyperendemic epidemic pandemic
Endemic disease
Is this a bit chilly present within geographical area
Epidemic disease
Excessive presents of a disease from what is expected
Pandemic
Worldwide epidemic
What can cause a disease outbreak
A common vehicle exposure
Characteristics of an outbreak from a common vehicle with single exposure
Explosive (Sudden and Rapids)
limited (Only people that share a common exposure)
Herd immunity
Resistance of a group of people to a disease because a large proportion of the members of the group are immune
Conditions for herd immunity
Disease agent only in single host species
Direct transmission
Solid immunity after infection
Incubation period
Time interval between contracting an infection and onsets of clinical illness
Epidemic curve
Distribution of time of onset of disease
Attack rate formula
Number of suspected person exposed to illness who became ill/ number of persons exposed overall
Case distribution
Case distribution on terms of time and place
Control measures of epidemics
Control of current outbreak
Prevention of future oitnreak
System used when there’s several possible causal agents to an outbreak
Cross tabulation in outbreak investigation
Prevention definition
Measures not only to prevent occurrence of disease such as risk factor reduction, arrest it’s progress , reduce its consequences once established
Levels of prevention
Primordial
Primary
Secondary
Tertiary
Primordial prevention
Prevention of risk factors
Change in social and environmental conditions
Primordial prevention important for what type of diseases
Chronic diseases
Primordial Prevention définition
Prevention of the emergence of living patterns that contribute to increased risk of disease
Types of primordial Prevention
Legislation taxation code of practice health promotion Avoidance of risks genetic counseling diet nutrition
Primary prevention Purpose
Limits the incidence of disease by controlling causes and risk factors
Two strategies of primary prevention
Average risk population strategy
high-risk individual strategy
Advantages of average risk population strategy
It’s radical
large potential for a whole population
behaviorally appropriate
Disadvantages of average risk population strategy
Small benefits to individuals

poor motivation of subjects
poor motivation of physicians
benefits to risk Ratio low
High-risk individual strategy advantages
Appropriate for individuals
subject motivation
physician motivation
favorable benefits to risk ratio
High-risk individual strategy disadvantages
Difficulty in identifying high-risk individual
temporary effects
limited effects
behaviorally inappropriate
Secondary prevention
Cure patients and reduce the more serious consequences of this is through early diagnosis and treatment
At what time In disease timeline do you use secondary prevention
During onset of diseaSe and normal time of diagnosis
What type some type of secondary prevention
Opportunistic or targeted screening
Improving uptake of services
allowing affordable self-care
Clinical services
What are the clinical services in secondary prevention
National technical guidelines
available clinical and preventive services
quality of care
institutional capacity
available and affordable drugs and diagnostic tests
quality of generic drugs
drugs prophylaxis
laboratory available
personnel available
Tertiary prevention
Reducing the progress of complication of an established Disease
Try to reduce impairment,
disabilities, suffering,
and promotes patients adjustments to incurable conditions
Some type of tertiary prevention
Surgery prosthesis occupational therapy physiotherapy speech therapy
What are the 3 steps in epidemiology
Count number of events in population
Divide number of events by number of person in that population
Compare rate from different population and infere about existing differences
Types of measures used in health and disease
Count Proportion Ratio Rate Prevalence Incidence Mortality rates Cumulative incidence Risk Incidence density Adjused rates Public health indices
What is count
Number of cases of a disease or health problen being studied
What is proportion
Fraction in which numerator is included in denominator
Usually expressed as percentage
Why are counts still useful in epidemiology
For some disease even one case is still a problem like smallpox
Can lead to investigations of usual disease
What is a ratio
Fraction in which the numerator is not included in the denominator
What is rates
Numerator over a denominator over a perdiod of time
What is prevalence
Proportion of individuals in a population who have the disease at a specific point in time or over specified period
Numerator has new and old cases
What is incidence
Number of cases at particular time who newly have the disease
Numerator has only new cases
When is prevalence useful
In case of chronic disease
When is points prevalence useful
In case of episodic prevalence
When is period Prevalence useful
In case of lifetime prevalence especially suitable for cases in which type of onset of illness is not known especially for psychiatric cases
Incidence rates definition
Number of new cases of disease in a group over a certain time. Over the amount of personal time during which the new cases arose
Why is it important to know characteristics of person and the time in the incidence rates
Because the denominator exclude any individuals had already disease of interest or are not capable of developing the disease in a specific period of time
What is incidence density
Number of new cases of disease in specified period of time over the number of person time at risk during the period
What is cumulative incidence
Number of new cases of disease in specific time over the total number of disease-free individuals at the beginning of the specified time
What is the probability that an individual disease-free beginning of time. Will develop the disease in that given period time
What is the relationship between prevalence and incidence
Prevalence depends on incidence rates and duration of the disease
What are two examples of public health rates
DALYs
QALYs
What is DALYs
Disability adjusted life years which is the measure of the burden of disease on a population and the effectiveness of intervention
What is QALYs
The quality adjusted life years which is the adjustment of life expectancy taking into account the presence of chronic conditions causing appointment disability or handicap
What is the only event in life with long-term probability of one with certainty for a living person’s
Death
Counts as a mortality measure
Count the number of deaths from particular disease
Rates in mortality measure
Number of deaths due to particular disease over a group over a period of time
What is the annual mortality rates
Is the all cause mortality rate for sub groups based on age or gender or area
What is the cause specific mortality rates
It is it is it specific mortality rates which is limited to a particular diagnosis
Case Fatality rates
Proportion of persons with a particular disease that die from the disease
Proportionate mortality
Proportion of all deaths caused by specific diseases in a period
Years of potential life lost
Measure of premature mortality
Mortality rates
Incidence rates of the witches number of deaths over mid yyear population
Crude mortality rates
Ratio of number of deaths during the year over average population in that year
Age specific mortality rates
Natality rate calculated for specific age bands
Age adjusted mortality rate
Process to even out the effect of different age distribution went to a more mortality rates from two different populations are being compared
Odds of disease
Number of new cases of disease in. Time over the number of persons with did not become a case during the time. But could have potentially become cases
What are some public health indices
Crude mortality rates birthrates fertility rates infant mortality rates neonatal mortality rates maternal mortality rates
What are the two big divisions of epidemiological studies
observational
experimental
What are the two division of observational epidemiological studies
Descriptive
analytical
What are the possible study done in descriptive observational epidemiological studies
Case Reports Case series Cross sectional Prevalence studies Ecological studies
What are the different type of observational analytical epidemiological studies
Case control
cohort studies
cross-sectional
What are the different type of experimental epidemiological studies
Clinical trials
field trials
community trials intervention
What are the different components of epidemiological studies about
Study factor
study subjects
exposure
Health outcome or disease
Is observational studies manipulated randomized?
Neither
Is experimental studies manipulated or randomized
Yes both
Is quasiexperimental studies manipulated or randomized
manipulated but not randomized
What factor can have a relationship with disease
Exposure
In observational studies who determines the exposure
The subjects
Why are most epidemiologic studies observational
Because experimental studies are mostly impractical and unethical
Advantages of observational studies
Natural setting No ethical concern Low Cost Convenience Data already existing
Disadvantages of observational studies
No randomization
What is descriptive studies
Study that presents occurence and distribution of disease
Organizes and summarizes data accordiing to person , place and time
3 questions in descriptive study
Who has been affected
Where have they been affected
When have they been affected
When is descriptive studies for individual useful
To show individuals healths characteristics
estimate disease frequency
extent of public health problem
identify populations at greatest risk
estimate time trends
planning and health care resource allocation
suggest hypothesis about causation
What’s do you use to perform descriptive study analysis
Tables
rates
Measures of central location of dispersion
graphic charts maps
How do you determines where whos at risk in descriptive study
Demographics (Age, sex,ethnicity) socioeconomic background (Education ,occupation ,access to services ) Other factors (blood group ,vaccination status ,smokers)
How do you present data from who is at risk in Descriptive study
Tables or graphs
How important is age in descriptive study and why
Very important as it reflects susceptibility, differences in exposure ,latency incubation period
How does sex play into descriptive study
Men and women are different in susceptibility physiological response exposure due to habits, occupation service utilization
How do you present that comparing men and women in descriptive study
table
What information does place gives in descriptive study
Geographic distribution
cluster of cases
dissemination route
What means of presentation do you use to show place impact in descriptive study
Maps
Charts
How does time play into descriptive study
Variation of a time of health events which could be annual seasonal daily hourly
interested in onset of symptoms date of reporting