BIO2720 Epidemiology Study Guide - Flashcards

Practice flashcards covering key epidemiology concepts from the notes.

What is epidemiology?

The study of when and where diseases occur and how they are transmitted in populations.

Historically, what did people think caused contagion or disease?

Evil spirits, bad thoughts or deeds, improper living; emotions and immunity later linked to disease.

Do a large or small percentage of bacteria, viruses, and fungi in the world cause disease?

A small percentage.

What positive uses do bacteria have in everyday life?

Decomposition, food production, medicines, and gut microbiota help vascular development.

Why is John Snow considered the Father of Epidemiology, and which disease did he study?

For his work tracing cholera transmission and pioneering mapping; studied cholera and the Broad Street Pump in London.

Pathology: what is it?

The study of disease.

Etiology: what does it mean?

The study of the cause of a disease.

Pathogenesis: what is it?

The mechanism by which a disease develops.

Infection: how is it defined?

Colonization of the body by pathogens.

Disease: how is it defined?

An abnormal state in which the body is not functioning normally (infection can occur without symptoms).

Transient microbiota, normal microbiota, and symbiosis: define each.

Transient microbiota: present for days–months; Normal microbiota: permanently colonize the host; Symbiosis: relationship between normal microbiota and host.

Name two examples of permanent resident bacteria.

Escherichia coli (from food/environment); Lactobacilli (part of normal microbiota from birth).

Can viruses, bacteria, fungi, protozoans, and prions be transient flora?

Yes, they can all be transient flora.

Define commensalism, mutualism, and parasitism with examples.

Commensalism: one benefits, other unaffected (e.g., Corynebacteria). Mutualism: both benefit (e.g., E. coli in gut). Parasitism: one benefits at the host’s expense (e.g., H1N1).

What is an opportunistic pathogen?

A normally harmless microbe that can cause disease in a susceptible person (e.g., Candida albicans).

Where in the body are normal microbiota found?

Eyes, nose and throat, mouth, skin, large intestine, urinary and genital systems (lower urethra in both sexes and vagina in females).

What is microbial antagonism? How do normal microbiota protect the host?

Competition between microbes; they protect by occupying niches, producing acids, and producing bacteriocins.

Koch’s postulates: what are they?

1) Microorganisms isolated from a dead animal; 2) grown in pure culture; 3) inoculated into a healthy animal; 4) disease reproduced; microorganisms isolated from this animal.

Which organism did Koch study for his postulates?

Bacillus anthracis (anthrax).

Can one organism cause several different diseases? Provide examples.

Yes. Streptococcus pyogenes causes strep throat, scarlet fever, puerperal fever, osteomyelitis; Mycobacterium tuberculosis can affect lungs, skin, bones, and internal organs.

Differentiate a symptom, a sign, and a syndrome.

Symptom: subjective change felt by patient; Sign: objective measurable change; Syndrome: a specific group of signs/symptoms accompanying a disease.

What is a communicable (contagious) disease?

A disease easily spread from one host to another (e.g., chickenpox, genital warts, typhoid fever).

What is a non-communicable disease?

A disease not transmitted from one host to another (e.g., tetanus).

Define incidence, prevalence, sporadic disease, endemic disease, epidemic disease, and pandemic disease.

Incidence: number of new cases in a population/time; Prevalence: total cases in a population at a given time; Sporadic: occasional cases; Endemic: constantly present; Epidemic: many cases in a region in a short time; Pandemic: worldwide.

What is herd immunity?

Immunity in most of a population, reducing disease spread.

Define acute, chronic, subacute, and latent diseases.

Acute: rapid onset, short duration; Chronic: slow development, long duration; Subacute: between acute and chronic; Latent: period of no symptoms with possible later activation.

Local infection vs systemic infection; what is a focal infection?

Local: limited to a small area; Systemic: throughout the body via the bloodstream; Focal: systemic infection that began as a local infection (e.g., teeth, sinuses, appendix).

Define bacteremia, septicemia, toxemia, and viremia.

Bacteremia: bacteria in the blood; Septicemia: growth of bacteria in the blood; Toxemia: toxins in the blood; Viremia: viruses in the blood.

Primary infection vs secondary infection; examples.

Primary: initial illness; Secondary: opportunistic infection after a primary infection (e.g., Pneumocystis pneumonia in AIDS).

What is a subclinical disease?

No noticeable signs or symptoms (inapparent infection).

List some predisposing factors that increase disease susceptibility.

Inherited traits (e.g., sickle cell), climate, fatigue, age, lifestyle, exposure intensity, nutrition, crowding, cultural factors, anatomical factors (short urethra in females), chemotherapy.

What are the five stages of disease development?

Incubation; Prodromal; Illness (acute); Decline; Convalescence.

What is a reservoir of infection and what are the three main categories?

Reservoir: continual source of infection; categories: Zoonoses, Animal reservoirs, Nonliving reservoirs.

What are zoonoses and what does sylvatic mean?

Zoonoses are diseases transmitted from animals to humans; sylvatic means wild.

Give examples of sylvatic diseases.

Lyme disease (ticks), Hanta virus (deer mouse), Ebola; sometimes Lyme involves Ixodes scapularis ticks.

Direct contact vs indirect contact vs droplet transmission?

Direct contact requires close contact; indirect via fomites; droplet transmission via airborne droplets.

What is a fomite?

An inanimate object that can carry infectious agents (clothes, utensils, furniture).

What is a vehicle of transmission and give examples.

Inanimate reservoir that transmits disease; examples include food and water.

What is a vector in disease transmission? Difference between mechanical and biological transmission?

Vector: arthropod that transmits disease (e.g., fleas, ticks, mosquitoes). Mechanical: pathogen carried on the vector’s body; Biological: pathogen reproduces in the vector and is transmitted via bite, feces, or vomit.

What is a nosocomial infection and which bacteria are major culprits?

An infection acquired in a hospital; 5–15% of patients; major bacteria: Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Clostridium difficile.

What measures help control nosocomial infections?

Infection control, aseptic technique, hand washing, staff education, isolation rooms, appropriate antibiotic use.

What is an emerging infectious disease and what factors contribute?

Diseases that are new or increasing in incidence; factors include new strains, antibiotic resistance, climate change, modern transportation, ecological/disasters, public health failures.

What did John Snow, Ignaz Semmelweis, and Florence Nightingale contribute to epidemiology?

Snow mapped cholera in London; Semmelweis introduced handwashing to reduce puerperal fever; Nightingale improved sanitation to reduce epidemic typhus.

What is studied, compared, or reported in descriptive, analytical, and experimental epidemiology; case reporting; and nationally notifiable diseases?

Descriptive: data on occurrence; Analytical: compare diseased vs healthy groups; Experimental: controlled experiments; Case reporting: clinicians report diseases; Nationally notifiable: physicians report to authorities.

What are the roles of the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO)?

CDC collects and analyzes epidemiological information in the US; WHO collects and analyzes epidemiological information worldwide.

Define morbidity, mortality, morbidity rate, and mortality rate.

Morbidity: incidence of a notifiable disease; Mortality: deaths from notifiable diseases; Morbidity rate: cases per population in a given time; Mortality rate: deaths per population.