Epidemiology Overview Quiz

Study Notes

Epidemiology

Study of the occurrences, distribution, and determinants of health-related states or events in specified populations.
It’s key for preventing disease.

Epidemiologic Triad

Host - Intrinsic factor (humans are usually the primary host)
Agent - Etiologic factor (virus, bacteria, fungi, parasites, etc.)
Environment - Extrinsic factor

John Snow

Anesthesiologist known as the “Father of Epidemiology”.
Studied the cholera epidemic in the Golden Square of Soho district, London (1854).

In Epidemiology

Distribution (Descriptive Epidemiology) - Answers the questions WHEN, WHERE, WHO:
- Time (when): When did the disease occur?
- Place (where): Where did the disease occur?
- Person (who): Who was affected by the disease?
Determinants (Analytic Epidemiology) - Answers the WHY and HOW:
- Discovers causes, risk factors, and modes of transmission.
- Includes causes (including agents), risk factors (including exposure to sources).

Descriptive vs. Analytic Epidemiology

Descriptive epidemiology identifies patterns among cases and populations by time, place, and person. Surveys are used to understand the population affected by a particular disease, noting age, sex, and occupation.
Analytic epidemiology focuses on searching for causes and effects (the why and how).

Patterns of Occurrence and Distribution

Sporadic - Intermittent occurrence of a few isolated (scattered) and unrelated cases.
Endemic - Continuous occurrence throughout a period of time of the usual number of cases in a given locality. It refers to the constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area.
Epidemic - An unusual, large number of cases in a relatively short period of time, usually in weeks.
- Point source: Food poisoning
- Cyclical pattern: Dengue fever
- Secular trend: Influenza
- Propagated: HIV/AIDS
Pandemic - Simultaneous occurrence of an epidemic of the same disease in several countries, affecting a large number of people.
- Pandemic diseases:
  - MERS-CoV
  - Asian Flu
  - Spanish Flu (1918-1919) - 40 to 50 million deaths
  - Antonine plague
  - Meningococcemia
  - AH1N1
  - Black Death / Bubonic plague caused by Yersinia pestis
  - HIV/AIDS
  - Ebola and COVID-19 caused by SARS-CoV-2

RA 3573 (Law on Reporting of Notifiable Diseases)

Report to provincial and duty health office
Midwife reports under the supervision of the nurse
REPORT Measles and Polio within 24 hours
REPORT Tetanus Neonatorum, Severe and acute diarrhea, and HIV within a week.

RA 11332 (Mandatory Reporting of Notifiable Diseases)

Mandatory Reporting of Notifiable Diseases and Health Events of Public Health Concern Act
Surveillance and Response to Notifiable Diseases, Epidemics, and Health Events of Public Health Concern

Chain of Infection

Agent - Any microorganism capable of producing a disease (Bacteria, virus, fungi, parasites).
- Disinfection: Killing of microorganisms but NOT their spores.
- Sterilization: Killing of ALL MICROORGANISMS including spores.
- Autoclaving: 15 pounds pressure, moist heat, and 250 degrees Fahrenheit (121°C). Black strips suggest a successful autoclave.
Reservoir - Natural habitat where an agent normally lives, grows, and multiplies.
- Human reservoirs: Measles, mumps, HIV, and STIs.
- Animal reservoirs: Anthrax (sheep) and rabies (dogs).
- Environmental reservoirs: Histoplasmosis (soil).
Carrier - A person or animal that harbors a specific infectious agent WITHOUT discernible clinical disease and serves as a potential source of infection.
Portal of exit - Path by which a pathogen leaves its host. Many portals of exit are identical to portals of entry.
- Influenza and TB exit the respiratory tract.
- Cholera bacteria exit in feces.
Modes of transmission - Considered the WEAKEST link. It can be easily broken by HAND WASHING.
- Hand washing is the NUMBER ONE way to stop the transmission of infections.
- Hand hygiene is the single MOST effective and important technique in preventing and controlling the transmission of infection.
Handwashing / hand hygiene:
- 3 elements:
  - Soap (1-3 ml)
  - Water - Running, clean water
  - Friction - MOST important element
- HANDWASHING TIME: (40-60 sec)
  - Minimum time for each hand: 15 seconds
  - Average time: 20 seconds for each hand.