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Methods of Outbreak Epidemiology
- Clinical observations
- Epidemic curve
- Incubation period
- Attack rate
- Case mapping
- hypothesis formulation and confirmation
- Draw conclusions
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The pattern of symptoms suggests possible infectious agents
Clinical observations
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Possible symptoms of an outbreak include:
- fever
- nausea
- vomiting
- diarrhea
- stomach pain
- headache
- rashes
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A graphic plottin gof the distribution of cases by time of onset.
Epidemic curve
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In conjunction with information about symptoms, provides clues to possible infectious disease agents
Incubation period
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Used frequently to describe the occurence of foodborne illness, infectious disease, and other acute epidemics
attack rate
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Attack rate formula
Ill/(Ill + Well) X 100
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Can be used to locate cases in relation to environmental exposures to pollution, identify contacts of cases, and conduct many other innovative health research investigations
Case mapping
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Using the information gathered, the epidemiologist may formulate a hypothesis regarding the causative agent
Hypothesis formation and confirmation
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Plan for the prevention of future outbreaks
Draw conclusions
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People are exposed continuously or intermittently to a harmful source, brief or long exposure.
Common source
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Intermittent exposure
Epidemic curve with irregular peaks that reflect timing and extent of exposure
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Continuous exposure
Causes cases to rise gradually and plateu rather than peak
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Spread person to person, may have multiple waves with an epidemic curve that has progressively taller peaks an incubation period apart
Propagated
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Ability of a test to identify correctly all screened individuals who actually have the disease.
Sensitivity
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Ability of a test to identify nondiseased individuals who actually do not have a disease.
Specificity
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Proportion of individuals who are screened positive by a test and actually have the disease
Predictive positive value
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Proportion of individuals who are screened negative by a test and actually do not have the disease
Predictive negative value
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Choice of behavioral factors that affect how we live
Lifestyle
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The discipline that examines the social distribution and social dterminants of states of health
Social epidemiology
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The study of the role of behavioral factors in health
Behavioral epidemiology
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Non-REM sleep
- Stage 1- Muscle activity slows down, light sleep awakened easily.
- Stage 2- Starts within 10 minutes, lasts around 20 minutes. Breathing pattern and heart rate start to slow down. Longest stage.
- Stage 3- Brain begins to produce delta waves, large slow wave patterns. Breathing and heart rate at lowest levels.
- Stage four- rhythmic breathing and limited muscle activity. Feel groggy after being awakened from this stage.
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REM sleep
Usually begins 70-90 minutes after we fall asleep. Brain is very active, most dreams occur at this stage.
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Sleep cycle
- Lasts 90-110 minutes
- average person experiences 4-5 cycles each night
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Sleep ranks among the _______ most important considerations in maintaining good healt
3
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___% of US population experience sleep problems
62
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____% of US adults have NEVER discussed sleep problems with their physician
80
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Characterized by persistent sleepiness, general lack of energy
DOES- disorders of excessive sleepiness
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DIMS
Disorders of initiating and maintaining sleep
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Sleep terror disorders and sleepwalking
parasomnias
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Major Sleep Disorders
- Insufficient sleep
- Insomnia
- Sleep apnea
- Shift work sleep disorder
- Restless legs syndrome
- Narcolepsy
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Cannot initiate or maintain sleep
May be transient
May persist
High likihood of psych sequelae
Insomnia
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Self-limits sleep
Transient
Lowe liklihood of sequalae
Insufficient sleep
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Effects of insomnia on health
- Poor concentration
- Decreased QOL
- Contributes to depression and anxiety
- Decrements in work quality
- Increased healthcare utilization
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Sleep apnea percentage by age group
- Children- 2-3%
- Middleaged adults- 5-7%
- older adults- >15%
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Narcolepsy epidemiology
Men or women?
Age of onset?
Prevalence?
- 1 in 2000 in US
- Men and women affected equally
- Can present at any age, but mostly 15-30 years and 6% prior to 10
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Fundamentally a sleep disorder
Results in loss of boundaries between sleep and wakefulness
Can't stay awake during the day, can't sleep during the night
Narcolepsy
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Symptoms of Narcolepsy
- Sleepiness with more or less discrete attacks
- Cataplexy
- Hallucinations
- Sleep paralysis
- Disrupted nocturnal sleep
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Sleep disorders are common
- 70 million adult americans have clincially significant sleep problems
- Insomnia affects 1/3 of the population
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Sleep disorders are treatable
- Pharacotherapy
- Behavioral therapy
- Continuous positive airway pressure
- Surgical therapy
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Sleep disorders are underdiagnosed
95% of people with as leep problem ramin unidentified and undiagnosed
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Populations Pyramid Structure
- Males on the left, females on the right
- Population in five year age bands
- From top to bottom: Old dependants, economically active, young dependants.
- Usually in % to make for easier comparisons between countries
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Slope of the pyramid indicates
death rate
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WIdth of the base is related to
birth rate/fertility rate
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Height of the graph can indicate
life expectancy
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Proportions of men and women can suggest
male or female migrations
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"kinks" indicate dramatic
reductions in brith rate or increases in death rates in the past
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Area of graph indicates
total population
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Overall shape can indicate
whether it is an economically more developed country or an economically less developed country
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A broad base population pyramid means:
- Increase food production
- Build more homes and schools
- Plan fo rmore job oppurtunities for the young in the future
- Implement birth control program/campaigns
- Usually agricultural with problems of overpopulation
- Many dependants
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Triangle shaped pyramid is
typical of countries in poorer parts of the world (LEDCs)
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In triangle shaped pyramids with a shortened base, what is happening?
The gobernement is encouraging couples to have smaller families.
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A narrow based population pyramid means:
- Work out incentives to encourage more births
- Hiring foriegn labor
- Proper medical services and health care for the aged
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Population pyramid with both low birth and low death rate
Typical of MEDCs in richer parts of the world
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Characterized by high birth and high but fluctuating death rates. When births only slightly exceed deaths, the population gros slowly.
Stage 1
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Declining death rates with high birth rates
2nd stage
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Birth rate falls and death rate remains low, population size levels off
Stage 3
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Very low birth and death rates. Very slight % increases in population
4th stage
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Human Genome Project
Jointly coordinated by the US department of Energy and the National Institutes of Health
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One goal of HGP
TO identify all of the genes in human DNA
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A subfield of epidemiology that uses molecular markers in additiont o genes to establish exposure-disease relationships
Molecular epidemiology
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Genetic Marker
Used in reference to susceptibility genes
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Field concerned with the identification of inherited factors that influence disease and how variation in the genetic material interacts with environmental factors to increase or decrease risk of a disease.
Genetic epidemiology
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Examples of conditions with a genetic bases
- hemophilia
- Tay-Sachs
- Sickle cell
- Down's syndrome
- BRCA1 and BRCA2 genes
- COngenital malformations
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Sex-linked disorder
hemophilia
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Hemophilia
- Affected persons are always males
- Males inherit the trait from mothers who are carriers
- Females inherit the carrier gene from affected fathers
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Treatment for hemophilia
- Prophylaxes- continued injection of clotting factors
- After injury- transfusion of clotting factors
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Denotes those diseases for which two copies of an altered gene are required to increase risk of the disease
Autosomal recessive
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Examples of autosomal recessive diseases
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Refers to a situation in which only a single copy of an altered gene located on a non sex chromosome is sufficient to cause an increased risk of disease
Autosomal dominant
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Down's syndome
Caused by the presence of an extra 21st chromosome
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Results of Down's syndrome
- Heart disease
- Visual/hearing impairments
- Ahlzheimer's
- Thyroid problems
- diabetes
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Edward's syndrome
Caused by abnormality in chromosome 18, low survival rate, similar to Down's
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Congenital malformations
Defects present at birth
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Causes of congenital malformation
- Genetic/chromosomal
- Environmental
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Incidence
- 2-3% newborn
- 40-60% have unknown cause
- Genetic cause- 10-15%
- Environmental cause- 10%
- Multi- 20-25%
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Major Structural Birth Defects
- Result from a malformation, deformation, or disruption in one or more parts of the body
- Are present at birth
- Have a serious adverse effects on health, development, or functional ability
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Refers to the study of diseases and conditions that are linked to environmental factors.
Environmental epidemiology
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Effects of radiation on unborn children
- Microencephaly
- Skull defects
- Spina bifida
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Effects of atomic bomb in Japan
- 25% aborted
- 25% had abnormalities of CNS
- 25% died by <1 year
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Any infection can by pyrogenic, hyperthermia can be
teratogenic
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6 criteria pollutants
- CO- vehicle exhaust
- Sulfur dioxide- coal burning
- Nitrogen dioxide- vehicle/industry
- Ozone- smog
- Particulate matter
- Lead- gasoline additive
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Air pollution consequences
Mortality, coronary heart disease, chronic obstructive pulmonary disease, asthma, and lung cancer
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Factors contributing to global warming
- Use of fossil fuels
- Widespread deforestation
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Global warming linked to
- Northward movement of disease-carrying arthropods
- Melting glaciers
- Extreme climatic conditions such as heat waves
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Alcohol effects on unborn child
Fetal alcohol syndrome
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DDT
Use discontinued because of possible adverse animal and human health effects, eg, damage to bird species
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Dioxins
Possible disrupters of immune, endocrine, reproductive, and nervous systems.
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Polychlorinated biphenyls
Dioxin-like chemicals designated as probable human carcinogens
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Lead
Exposure is assoicated with serious central nervous system effects and other adverse health consequences, even when ingested at low levels.
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Mercury
Highly toxic metal that is particularly hazardous to the unborn children of pregnant women.
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Nuclear facilities
- Include weapons production palnts, tests sites, and nuclear power plants
- Potential sources for exposure of the population to ionizing radiation
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Focuses on adverse health outcomes associated with the work environment.
Epidemiology and Occupational Health
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Potential hazards at work
- High noise levels
- Fumes and dusts
- Toxic chemicals
- Biohazards
- Stress
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studies the distribution and determinants of injuries (intentional and unintentional) in the poulation
Injury epidemiology
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5th most frequent cause of mortality in the US
Unintentioal injury
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