Public Health and epidemiology Flashcards
What is public health?
The science of protecting and improving the health of people and their communities. This work is achieved by promoting healthy lifestyles, researching disease and injury prevention, and detecting, preventing and responding to infectious diseases
What is epidemiology?
The branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors
The study of distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems
What are the determinants of health?
- income and social status
- social support networks
- employment and work conditions
- physical environment
- education
- healthy child development
- Biology and genetic endowment
- health services
- personal health practices and coping skills
Differentiate physician/veterinarian and epidemiologists
-A physician or veterinarian is concerned with the health of the individual whereas an epidemiologist is concerned with the health of the population overall
What are the components of epidemiology?
- occurrence of disease
- surveillance
- distribution of disease
- determinants
- control/prevention
Describe what is the prevelance of a disease
A statistical concept referring to the number of cases of a disease that are present in a particular population at a given time
- Proportion of disease affecting a population
- Compares # of people with condition to total # studied
- tells you widespread it is = usually a fraction, percentage or # of cases per 1000/ 10,000/100,000
- prevalence of data can help identify and target at-risk populations
What factors INCREASE prevalence?
- longer duration of the disease
- prolongation of life of patients without care
- Increased in new cases(increase in incidence)
- In-migration of cases
- Out-migration of healthy persons
- In-migration of susceptible people
- improved reporting
What factors DECREASE prevelance?
- shorter duration of the disease
- high case fatality rate from disease
- Decrease in new cases (decrease in incidence)
- In-migration of healthy people
- Out-migration of healthy people
- out-migration of cases
- improved cure rate of cases
What is the incidence of a disease?
- Measure of the probability of a given medical condition in a population in a specific period of time
- Tells you about the risk of acquiring it
What are the factors affecting incidence rate?
- New risk factors
- Oral contraceptives as exposure and increase in thrombo-embolism in women
- Food additives and cancer
- New virus( HIV and AIDS)
- Changing habits
- Increased smoking and development of lung cancer
- Fluoridated water and decrease I’m dental caries
What is mortality?
The incidence of death
What are the applications of mortality?
Applications of the darts include:
- Analyze characteristics of those dying: identify high mortality areas
- Enables appropriate responses and resources
- determine life expectancy
- compare mortality trends with other countries
- Looking at the Global Burden of disease
Give examples of mortality rates
- Crude mortality rate
- Counts all deaths
- All causes
- All ages and both sexes
- Denominator includes entire population
- All ages and both sexes
- Counts all deaths
- Cause specific mortality
- Rate at which deaths occur for a specific cause
- Age specific mortality rate:
- counts only deaths in specific age group
- Usually calculated for children less than 5 years of age
- Denominator includes only persons in that age group
- counts only deaths in specific age group
What factors influence death rates?
Increase in deaths is due to:
- Poor medical facilitates E.g. clinics, hospitals etc.
- Poor sanitation
- Poor hygiene and lack of clean water
- Natural disaster eg hurricanes, earthquakes, droughts, floods
- Limited education
- War
- Diseases eg AIDS
- famine severe drought
Explain the mortality rates that aren’t really rates
Live births as the denominator instead of actual group in which deaths are counted
- Infant mortality rate
- counts deaths in children less than 12 months of age, divides the number of live births in same time period - Maternal mortality rate
- counts deaths in women due to pregnancy or childbirth, divides by number of live births in same time period - Under-5 mortality rate
- counts deaths in first 5vyears of life, divides by number of live births in the hypothetical cohort of newborns
What is morbidity?
The rates of disease in a population
-measured by incidence and prevalence
What are the applications of morbidity?
- estimation of mortality
- compare trends
- impact of interventions(education; vaccines; new treatments)
- focus funds and resources
Contrast morbidity and mortality
Morbidity- proportion of illness in a population
Mortality- incidence of deaths in a population
What is public health surveillance?
Public health surveillance is the continuous, systematic collection, analysis and interpretation of health data needed for the planning, implementation, and evaluation of public health practice
What are the functions of surveillance?
- serve as an early warning system fir impending public health emergencies
- Document the impact of an intervention, or track progress towards specified goals
- Monitor and clarify the epidemiology of health problems, to allow priorities to be set and to inform public health policy and strategies
At what level does the methodology of surveillance occur?
Occurs at various Levels:
- local
- ministry of health
-State
- National
- public health service (UK)
- International
- CDC( Control for diseases and prevention and control)
- ECDC (European Centre for disease prevention and comtrol)
- WHO ( world heath organization)
What are the applications of surveillance data?
- Qualification of major health risks
- Monitoring and recording natural history of a disease
- Detecting outbreaks and epidemics
- Basis for research
- Initiation of interventions (education, vector-control etc)
- Deciding where to spend money
What are the types of surveillance?
Passive surveillance
Active surveillance
What is active surveillance?
When a health department is proactive and contacts health care providers or laboratories requesting information about diseases. While this method is more costly and labor intensive, it tends to provide a more complete estimate of disease frequency
What Is passive surveillance?
Health care providers report notifiable on a case-by-case basis. Passive surveillance is advantageous because it occurs continuously, and it requires few resources. However, it is impossible to ensure compliance by health care providers; moreover, cases occurring in people without access to care will frequently go unreported. Consequently, passive systems tend to under-reported disease frequency
What are noticeable diseases?
A specified list of noticeable diseases- diseases that health care providers and/or labs and hospitals are required to report to the state
Why we do notifiable disease surveillance?
- detect disease when and where it happens
- stop disease before it spreads
- study disease to strengthen the science
- improve how we prevent and control disease
- keep people healthy
What is the surveillance loop?
Objectives —> data analysis —> information —> action—> evaluation —> objectives
What are the 5 Ws of epidemiology?
- What = health issue of concern
- Who= person.
- Where = place
- When = time
- Why/how= causes, risk factors, modes of transmission
Explain the “What”- issue of concern of epidemiology
Infectious disease
- transmissible
- Type of outbreak
- Endemic
- epidemic
- pandemic
- Type of outbreak
- Non-transmissible
- Non-infectious disease
- lung cancer
- diabetes
- heart disease
What does endemic mean?
Infection is constantly maintained at a baseline level in a geographic area without external inputs
What dies epidemic mean?
Rapid spread of infectious disease to a large number of people in a given population with8n a short period of time
Cases usually presumed to have a common cause or related to each other in some way
What is a pandemic ?
Epidemic of disease that has spread across a large region; for instance multiple continents, or even worldwide, usually affect8ng a substantial population
Explain the “who-person” of epidemiology
- characteristics of people
- age, sex, ethnicity/race
- biological characteristics(immune. Status)
- acquired characteristics (marital status)
- activities(job, leisure, drug/alcohol/tobacco use)
- conditions (access to medical care, socioeconomic status)
What is the “where” of epidemio?
Geographical isolation and extent of the disease
What is the when 9f epidemiology?
The disease occurrence over time
What is the How of epidemiology?
Causes, risk factors
Give an example of analytical epidemiology
Hepatitis A outbreak
- case-patients had eaten at specific restaurant 2-6 weeks before onset of illness
- interviewed case-control patients to identify what they had eaten.
- interviewed group of people who had eaten there but did not get sick (the control group)
- 94% of case patients had eaten salsa compared to 39% of control
- Green onion implicated as source
What are the types of studies used in analytical epidemiology?
- Environmental
2. Observational
What is an observational study?
- exposure is under natural conditions
- cohort study
- case control study (this was the Hep. A and green onions example)
N. - cross-sectional study
What is an environmental study?
Investigator determines the exposure
-e.g. clinical trial
What are the types of infectious disease?
Emerging infectious diseases
Re-emerging infectious diseases
What are emerging infectious diseases?
These are due to newly identified and previously unknown infectious which cause public health problems either locally or internationally
What are Re-emerging diseases ?
These are those that are due to reappearance and increase of infections which are known, but had formerly fallen to levels so low that they were no longer considered a public health problem
-increasing in incidence relative to precious baseline
What are the basic stages of disease emergence?
Introduction
Establishment
Adaptation to new host and dissemination/spread
Explain the introductory phase of disease emergence
Introduction of agent into a new host population from reservoir:
- environment
- animal
- humans
What are the contributing factors of emergence and re-emergence?
- travel and commerce
- fast travel, more remote areas, wider exposure to foods and vectors
-economic development and land use
- failures in public health measures
- e.g. reduction in vaccine coverage
- global warming/climate change
- climate changes habitat for e.g, vectors
- human demographics and behavior
- overcrowding; mega-cities ; poverty
Microbial adaptation and change
-mutations, gene transfer (antibiotic resistance , toxins, etc)
Deliberately emerging terrorism
(Re)emergence=
Usually an interplay of multiple factors
What microbial factors contribute to emergence/reemergence?
- genetic adaptation and change
- polymicrobial infections
What are the host related factors that play a role in emerging/re-emerging?
- susceptibility
- demographics and behavior
- travel and trade
- bioterrorism
- occupational exposures
- inappropriate use of antibiotics
What are the environmental factors that contribute to emergence/reemergence?
- climate and weather
- land use
- technology and industry
- poverty and social inequality
- lack of public health resources
- animal population
- war and famine
Give an example of an emerging infection
Influenza pandemic
What is an antigenic shift ?
Sudden emergence of a novel/new strain of virus
- potential for epidemics and pandemics
- if the strain then spreads human. —> human
How can antigenic shift occur?
- flu virus from ducks/ birds infects humans
- flu virus from duck/birds infects intermediate host (pigs) and then infects humans
- viruses from ducks/birds and humans recombine in a mixing vessel(usually pugs) and from there infect humans
What is antigenic drift ?
Gradual change in composition of antigens on flu virus surface
What are the contributing factors for re-emergence of dengue?
Decline of vector control programs
- re-infestation
- insufficient financial resources
- rapid growth and urbanization of populations
- poor sanitation
- poverty
- increased travel
- presence of multiple stereotypes
- climate change
Give an example of a re-emerging infection
Dengue fever
What causes decrease in community(herd) immunity?
A sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness ) to make its spread from person to person unlikely. Even individuals not vaccinated(such as newborns and those with chronic illness ) are offered some protection because the disease has little opportunity to spread in the community
What are the communicable diseases that require quarantine?
Federal isolation and quarantine are authorized for these communicable diseases
-cholera
- diphtheria
- infectious tuberculosis
- plague
- small pox
- yellow fever
- viral hemmorhagic fevers (like Ebola)
- severe acute respiratory syndrome ( SARS, NERS, COVID-19)
- Flu that can cause a pandemic
What 8s isolation?
Isolation separates sick people with a quarantinable communicable disease from people who are not sick
What is quarantine?
Quarantine separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick.
How do isolation and quarantine help?
They help protect the public by preventing exposure to people who have or may have a contagious disease