epidemiology

Flashcard 1: Epidemiology Definition

Question: What is epidemiology?
Answer:

  • The study of diseases in populations and the factors that influence the frequency and distribution of diseases.

  • Aim: To predict future problems and make recommendations to prevent disease or limit its spread.

Key Definitions

Flashcard 2: Prevalence

Question: What does "prevalence" refer to in epidemiology?
Answer:

  • The total number of individuals in a population who have a disease or health condition at a specific time, usually expressed as a percentage of the population.

Flashcard 3: Incidence

Question: What is "incidence" in epidemiology?
Answer:

  • The number of new cases of a specific disease or health-related event during a particular time period (e.g., month or year).

Flashcard 4: Mortality Rate

Question: What is the "mortality rate"?
Answer:

  • The number or percentage of deaths in a given population.

Flashcard 5: Morbidity Rate

Question: What does "morbidity rate" refer to?
Answer:

  • The number or percentage of people who experience complications or illness from a disease.

Flashcard 6: Outbreak

Question: What is an "outbreak"?
Answer:

  • The occurrence of cases of a disease in excess of what is normally expected in a defined community, geographical area, or season.

Flashcard 7: Epidemic

Question: What is an "epidemic"?
Answer:

  • A sudden increase in the number of cases of a specific disease beyond what is normally expected, leading to rapid spread.

Flashcard 8: Endemic

Question: What does "endemic" mean in epidemiology?
Answer:

  • The usual occurrence of a disease in a specific geographical area.

Flashcard 9: Pandemic

Question: What is a "pandemic"?
Answer:

  • A disease that is widespread across multiple continents.

Types of Epidemics

Flashcard 10: Common Source Epidemic

Question: What is a "common source epidemic"?
Answer:

  • An epidemic arising from a single contaminated site, e.g., cholera.

  • Cases rise rapidly, and after the source is eliminated, the disease persists for about one incubation period.

Flashcard 11: Host-to-Host Epidemic

Question: What is a "host-to-host epidemic"?
Answer:

  • Spread from infected individuals to uninfected individuals, with multiple new sources created.

  • Example: Flu epidemic.

  • Starts slowly, peaks, and then wanes as susceptible individuals decrease.

Herd Immunity

Flashcard 12: Herd Immunity

Question: What is "herd immunity"?
Answer:

  • The resistance to the spread of a contagious disease when a high proportion of the population is immune, either through recovery or vaccination.

  • Protects those who are susceptible and cannot be vaccinated.

Flashcard 13: Epidemic Threshold

Question: What is the "epidemic threshold"?
Answer:

  • The minimum proportion of a population that must be immune to a specific pathogen to prevent an epidemic.

  • Vaccination aims to maintain immunity above this threshold.

Influenza

Flashcard 14: Types of Influenza

Question: What are the three types of influenza viruses, and which causes the most severe illness?
Answer:

  • Types A, B, and C.

  • Influenza A causes the most severe illness.

  • Animals serve as essential reservoirs for Influenza A, enabling pandemics.

Flashcard 15: Hemagglutinin (H) and Neuraminidase (N)

Question: What role do hemagglutinin (H) and neuraminidase (N) play in influenza?
Answer:

  • H (Hemagglutinin): A viral envelope glycoprotein that aids in attachment and adherence (18 subtypes, H1-H18).

  • N (Neuraminidase): An enzyme in the viral envelope that allows the virus to leave the host cell (11 subtypes, N1-N11).

Flashcard 16: Antigenic Drift vs. Antigenic Shift

Question: What is the difference between antigenic drift and antigenic shift in influenza viruses?
Answer:

  • Antigenic drift: Minor genetic changes due to random mutations, leading to small variations in the virus.

  • Antigenic shift: Major changes due to recombination of gene segments from different viral strains, creating new strains.

Case Definition and Study

Flashcard 17: Case Definition

Question: What is a "case definition"?
Answer:

  • A list of common symptoms for a particular medical condition that helps authorities identify if unusual cases are related.

  • It includes time, place, and personal characteristics of affected individuals.

Flashcard 18: Case-Control Study

Question: What is a "case-control study" in epidemiology?
Answer:

  • A study used to determine what factors link affected individuals (cases) and distinguish them from uninfected individuals (controls).

  • Helps identify risk factors for a disease outbreak.

Emerging and Re-Emerging Diseases

Flashcard 19: Emerging vs. Re-Emerging Diseases

Question: What is the difference between an emerging and a re-emerging disease?
Answer:

  • Emerging disease: A new or changing disease that is increasing in importance (e.g., Zika virus).

  • Re-emerging disease: A previously controlled disease that is now causing increasingly serious problems (e.g., multidrug-resistant tuberculosis).

Flashcard 20: Zika Virus Transmission

Question: How is Zika virus transmitted?
Answer:

  • Primarily through infected mosquitoes, but also via vertical (mother-to-baby) and sexual transmission.

Flashcard 21: Ebola Virus

Question: What are the key features of Ebola virus outbreaks?
Answer:

  • Causes hemorrhagic fever with up to 90% mortality.

  • Transmitted through contact with infected individuals or materials, often during burial.

  • Bats are believed to be the main reservoir.

Polio

Flashcard 22: Polio Transmission and Control

Question: How was polio historically transmitted, and how was it controlled?
Answer:

  • Transmitted via the fecal-oral route.

  • Lack of sanitation exposed children before 12 months, and maternal antibodies protected them.

  • Improved hygiene delayed exposure, reducing maternal protection.

  • Polio was controlled through widespread vaccination