[MT] Intro to Epi

The study of the distribution of the determinants of health-related states or events in specified populations, and the application of this study to the control of health problems

Epidemiology

Determinants of Health

· Income

· Housing

· Education

· Socio-economic Factors

· Employment

· Sociability

· Environmental Factors

· Gender

· Ethnicity

Epidemiology is derived from Greek word

Epidemic

Epi means

On/upon

Demos means

people

Logos means

study of

means the study of disease in human population.

Epidemiology

Aims: · To describe and measure the magnitude of _________ in human populations

health and disease problems

Aims: · To identify etiological factors in the _________

pathogenesis of disease

Aims: · To provide the data essential to the planning, implementation and evaluation of services for the ___________ and to the setting up of priorities among those services.

prevention and control of disease

______________ Epidemiology was concerned with investigation and management of epidemic of communicable diseases

Originally

______ Epidemiology was extended to endemic communicable diseases and non-communicable infectious diseases

Lately

_____________ Epidemiology can be applied to all diseases and other health related events

Recently

Scope of Epidemiology

Causation of the disease

Natural History of the disease

Heath status of the population

Evaluation of Intervention

Seven land marks:

Seven landmarks: Environment & human behaviors affect health

Hippocrates (460BC)

Seven landmarks: Quantified births, deaths, and diseases

John Graunt (1662)

Seven landmarks: Scurvy could be treated with fresh fruit

Lind (1747)

Seven landmarks: Established application of vital statistics for the evaluation of health problems

William Farr (1839)

Seven landmarks: Tested a hypothesis on the origin of an epidemic of cholera

John Snow (1854)

Seven landmarks: Systematized application of numerical thinking (quantitative reasoning)

Alexander Louis (1872)

Seven landmarks: Suggested criteria for establishing causation

Bradford Hill (1937)

Epidemiological thought emerged in

460 BC

Epidemiology flourished as a discipline in

1940s

Risk factors are present, disease has not yet developed

Susceptibility

No signs nor symptoms, but pathologic changes are already occurring in the host

Subclinical Disease

Signs and symptoms have already developed

Clinical Disease

Outcome of disease may lead to recovery, disability, or death

Recovery, Disability, or Death

· a factor that varies depending on the outcome

Causality

Factors or conditions already present in a host that produce susceptibility or disposition to a disease without actually causing it.

Predisposing

Age - Gender - Previous illness - Immunization

Predisposing

Factors that affect health through environmental influences in either a positive or negative way.

Enabling

Living conditions - Societal support - Services

Enabling

Essential factors for the development of diseases, injuries, conditions, disabilities, and death.

Precipitating

Exposure to pathogen - Lack of seat belt use

Precipitating

Factors that support the production and transmission of disease or conditions.

Reinforcing

Repetitive pattern of behavior: Smoking - Alcoholism - Physical inactivity (negative)

Reinforcing

Peer education - Family counseling - Support groups (positive)

Reinforcing

The microorganism that causes the disease. Either a virus, bacteria, fungi, or parasite.

Agent

E.g. Plasmodium

Agent

The agent infects the host, which then carries the disease and can have symptoms.

Host

E.g. Age, Genetics

Host

External factors that affect the spread of disease but are not directly a part of the agent or the host.

Environment

E.g. Climate, Water quality, Living conditions

Environment

Web of Causation

· Phenotype

· Social organization

· Behavior

· Environment

· Workplace

· Unknown factors

· Genes

· Microbes

· Elimination of specific disease by one or more measures of proven efficiency

Prevention

· Approaches and activities aimed at reducing likelihood of disease affecting individual

Prevention

Level of Prevention: Before risk factors develop

Primordial

Level of Prevention: Before disease develops

Primary

Level of Prevention: Early disease detection & treatment

Secondary

Level of Prevention: Managing established disease

Tertiary

What stage: Eliminate

Agent in the Reservoir

What stage: Reduce communicability

Agent in the Reservoir

What stage: Treatment

Agent in the Reservoir

What stage: Isolation - separation for the period of communicability of the case

Agent in the Reservoir

What stage: Quarantine - limitation of movement of persons who do not have the disease but are exposed to the agent for not longer than the agent's maximum incubation period

Agent in the Reservoir

What stage: Apply environmental control measure

Agent in Transit

What stage: These are usually aimed at the vectors and vehicles of the disease

Agent in Transit

separation for the period of communicability of the case

Isolation

o limitation of movement of persons who do not have the disease but are exposed to the agent for not longer than the agent's maximum incubation period

Quarantine

The antigen is introduced and the body makes antibodies to defend against the infection

Active Immunity

Acquired through the natural history of disease processes

Naturally-acquired Active Immunity

Antigen is deliberately introduced (e.g., live, attenuated virus particles as vaccines in MMR, BCG)

Artificially-acquired Active Immunity

The antibodies for the infection are the ones that are introduced

Passive Immunity

Transfer of antibodies from mother to baby, either through the placenta or through mother's breast milk

Naturally-acquired Passive Immunity

Injection of immune sera as vaccines (e.g., anti-tetanus antibodies, diphtheria antitoxin)

Artificially-acquired Passive Immunity

Strategies in Epidemiology

(1) confirming the existence (surveillance)

(2) developing a case definition and collating data on cases (Data-driven)

(3) analyzing data by time, place, and person (preventive)

(4) developing a hypothesis (containment)

(5) conducting further studies if needed (collaboration)

(6) policy strengthening (workforce, infrastructure, etc.)

Real-time reporting systems (outbreaks)

Disease Surveillance Systems

Monitoring specific populations or locations

Sentinel Surveillance

Using genetic sequencing to track variants of pathogens (e.g., COVID-19)

Genomic Surveillance

Statistical and computational models to predict outbreaks and assess interventions

Epidemiological Modelling

Leveraging machine learning to analyze trends

Big Data & AI

Mapping disease hotspots to inform resource allocation

Geospatial Analysis

Mass immunization efforts to build herd immunity

Vaccination Programs

Reducing disease transmission by targeting vectors

Vector Control

Public awareness campaigns

Health Promotion & Education

Separating infected individuals to prevent spread

Case Isolation & Quarantine

Identifying and monitoring exposed individuals

Contact Tracing

Limiting movement during pandemics

Travel Restrictions & Border Control

Integrating human, animal, and environmental health to prevent zoonotic diseases

One Health Approach

WHO and CDC collaborations to manage global health threats

International Cooperation

Enforcing health regulations (e.g., mandatory vaccination laws)

Legislation & Policy Interventions

Educating healthcare workers on outbreak response

Workforce Training

Building labs, hospitals, and surveillance centers

Infrastructure Development

Addressing health disparities and ensuring access to treatments

Equitable Access to Care

What data is · on-going survey used to assess the population trends

Surveillance Data

What data is · studies that focus on finding risk factors for a particular disease

Research Data

· to monitor key indicators of the health of a population (birth, death and fetal death)

Vital Records

· Completeness and accuracy of information needed to make an informed decision

Vital Records

· All information from _________ constitute the statistics for epidemiological data

vital records

What source: Questionnaire

Individual persons

What source: Survey

Individual persons

What source: Foodborne illness outbreak

Individual persons

What source: CDC's National Health and Nutrition Examination Survey

Individual persons

What source: Health data on U.S. residents

Individual persons

What source: Samples from the environment (river water, soil)

Environment

What source: Sensors for environmental changes

Environment

What source: Collection of water from area streams - check for pollutants

Environment

What source: Air-quality ratings

Environment

What source: Notifications to health department if cases of certain diseases are observed

Health care providers