ch 13

Question 1

1. what is incidence and how do you calculate it?
2. What is prevalence and how do we calculate it?
3. What is morbidity and how to calculate it?
4. What is mortality and how is it calculated?

Answer 1

1. incidence is the number of NEWLY diagnosed cases of a disease. It is used to determine a person’s probability of being diagnosed with a disease during a given period of time. Calculated by taking the number of new cases of a disease divided by the number of persons at risk for the disease
2. prevalence is the number of EXISTING cases in a population (new cases + existing cases/total population).
3. another word for illness (can be any illness or combination of different illnesses). Prevalence is often used to measure morbidity in a population.
4. Mortality is another term for death. A mortality rate is the number of deaths (due to a specific disease) divided by the total population.

Question 2

1. describe a communicable disease:
2. describe a non-communicable disease:
3. explain the difference between direct vs indirect contact
4. name the direct and indirect sources of communicable infectious diseases:

Answer 2

1. when an infected host can transmit the infectious agent to another host and establish infection in that host
   Highly communicable disease is contagious
2. infectious disease does not arise through transmission from host to host. Occurs primarily when a compromised person is invaded by his or her own normal microflora. Contact with organism in natural, non-living reservoir
3. direct is when it comes from physical contact or fine aerosol droplets. Indirect is when it passes from infected host to intermediate conveyor (vehicle) and then to another host
   * Vehicle – inanimate material, food, water, biological products, fomites
   Airborne – droplet nuclei, aerosols
4. direct: contact (ie kissing), droplets, vertical transmission (mom to fetus), and biological vetor like mosquito
   indirect: fomites, food/water, droplet nuclei and aerosols in air

Question 3

1. -6. What are the 6 patterns of infections and describe:

7. what is an acute infection vs chronic?

Answer 3

1. Localized infection – microbes enter the body and remains confined to a specific tissue
2. Systemic infection – infection spreads to several sites and tissue fluids usually in the bloodstream
3. Focal infection – when infectious agent breaks loose from a local infection and is carried to other tissues
4. Mixed infection – several microbes grow simultaneously at the infection site - polymicrobial (dental carries)
5. Primary infection – initial infection (ex: flu)
6. Secondary infection – another infection by a different microbe (ex. flu becomes pneumonia)
7. Acute: comes on rapidly and is severe but short-lived. < 10 days

Chronic: progress and persist over a long period of time with moments of latency

Question 4

1. What are the 4 patterns of infectious disease occurrence?
2. Define endemic:
3. Define sporadic:
4. Define epidemic:
5. Define Pandemic:

Answer 4

1. endemic, sporadic, epidemic, and pandemic
2. disease that exhibits a steady frequency over a long period of time in a particular geographic locale
3. when occasional cases are reported at irregular intervals
4. when prevalence of a disease is increasing beyond what is expected
5. epidemic across continents

Question 5

1.- 4. What are the 4 steps in Koch’s postulates?

Answer 5

1. find evidence of a particular microbe in a disease.
2. isolate the microbe and grow it in the lab
3. inoculate a healthy subject and see what happens
4. reisolate the microbe from the subject

Question 6

1. what is a nosocomial infection?
2. How many cases are there in a year in the US, and how many people die from nosocomial infections?
3. Define prevalence:
4. Define incidence:
5. Define mortality:
6. Define morbidity:
7. what is epidemiology?

Answer 6

1. a hospital acquired infection
2. 2-4 million cases per year, and 90,000 deaths
3. the total number of existing cases as a percent of the total population
4. a measure of the number of new cases over a period of time compared to the general population
5. total number of deaths caused by a disease
6. total number of people afflicted with a certain disease
7. the study of disease

Question 7

1. How do A-B exotoxins work? Which part is the active component?
2. What does A do once released in cell?
3. Give an example of a disease caused by A-B exotoxin:

Answer 7

1. A is active. B attaches to receptor on target. Target ingests A-B complex. A is released once inside of target.
2. A acts on ribosomes and blocks protein synthesis that would kill A.
3. diptheria

Question 8

1. What is ID?
2. Microbes with smaller IDs have greater or lesser virulence?
3. Lack of ID will or will not result in infection?

Answer 8

1. Infectious Dose. Minimum number of microbes required for infection to proceed
2. greater
3. will not

Question 9

1. what are the earliest symptoms of disease?

2. What are signs of inflammation:

Answer 9

1. Inflammation: fever, pain, swelling, sore
2. edema, Granulomas and abscesses (walled-off collections of inflammatory cells and microbes), and lymphadenitis (swollen lyph nodes).

Question 10

1. How do people develop their microbiome?
2. What are the 7 steps in the course of an infection?
3. Name factors that contribute to a host’s susceptibility to infection:

Answer 10

1. Babies get first exposed when they’re born by the breaking of fetal membranes and introduction to environmental microbes.
2. portal of entry, adhesion, invasion, multiplication, infection of target, disease, portal of exit.
3. old age, infancy, genetic and acquired defects in immunity, surgery and transplants, diseases like cancer or diabetes, immunosuppressive drugs, stress, other infections

Question 11

1.-4. Name and describe the 4 stages of infections:

Answer 11

1. incubation- hours -years. No symptoms
2. Prodromal stage – vague feelings of discomfort; nonspecific complaints
3. Period of invasion – multiplies at high levels, becomes well-established; more specific signs and symptoms
4. Convalescent period – as person begins to respond to the infection, symptoms decline

Question 12

1. what are portals of entry?
2. ………. agents originate from source outside the body, …………. agents already exist on or in the body (normal flora)
3. What is STORCH, and what does it stand for?

Answer 12

1. conjuctiva, respiratory gastrointestinal and urogenital tracts, pregnancy and birth, and skin
2. Exogenous, Endogenous
3. pathogens that infect during pregnancy. Syphilis, Toxoplasmosis, Other diseases (hep B, AIDS, and chlamydia), Rubella, Cytomegalovirus, and Herpes simplex virus.

Question 13

1. what are virulence factors?
2. …………….. dissolve extracellular barriers and penetrate through or between cells
3. what is toxigenicity?
4. what are the 2 classes of bacterial toxins, how does each work, and an example of each.
5. Are endotoxins create specific effects or general? Exotoxins? Which one is more potent?

Answer 13

1. traits used to invade and establish themselves in the host, also determine the degree of tissue damage that occurs – severity of disease
2. exoenzymes
3. – capacity to produce toxins at the site of multiplication
4. endotoxin- general effects. Not secreted by cell, but rather released after infection starts (LPS)

exotoxin- toxin molecule secreted by live bacterial cells into the infected tissue. Specific to damage target cell (hemolysin and A-B toxins)

5. general, specific, exotoxin

Question 14

1. How does adhesion (step 1) happen?
2. Name some apparatus that aid in adhesion:
3. Name a few ways that pathogenic microbes can survive host defenses:
4. Some pathogens, such as ………….. , produce a secretion system to insert specialized virulence proteins directly into the host cells.

Answer 14

1. microbes gain a stable foothold at the portal of entry; dependent on binding between specific molecules on host and pathogen
2. Fimbrae, Flagella, Glycocalyx, Cilia, Suckers, Hooks, Barbs
3. antiphagocytic factors (glycocalyx). Some have ability to survive intracellular (m. tuberculosis) phagocytosis, and some produce leukocidins (kill white blood cells)
4. salmonella

Question 15

1. -3. What are the 3 signs of infection in the blood?

4. -5. What are the 2 types of septicemia?

Answer 15

1. Leukocytosis – increase in white blood cells
2. Leukopenia – decrease in white blood cells
3. Septicemia – microorganisms are multiplying in the blood and present in large numbers
4. Bacteremia – small numbers of bacteria present in blood not necessarily multiplying
5. Viremia – small number of viruses present not necessarily multiplying

Question 16

1. What are the 5 portals of exit for infections?

Answer 16

1. Respiratory, Skin scales, Fecal exit, Urogenital tract, Removal of blood

Question 17

1. what is a carrier?
2. what is an asymptomatic carrier, and the 3 types of asymptomatic carriers
3. what is a passive carrier?
4. what is a fomite?

Answer 17

1. person who inconspicuously shelters a pathogen and spreads it to others; may or may not have experienced the disease.
2. shows no symptoms. Can be during incubation or convalescent stages or can be a chronic carrier, sheltering pathogen for a long period.
3. contaminated healthcare provider picks up pathogens and transfers them to other patients
4. an inanimate object that can transport a pathogen. Ex: ties, mops, blankets, clothing, stethoscope.

Question 18

1. What is latency?
2. what is a chronic carrier?
3. what is Sequelae?
4. What is a reservoir?
5. What is a source?

Answer 18

1. in a chronic disease, microbes can re-activate and recur.
2. person with a latent infection who sheds the infectious agent.
3. long-term or permanent damage to tissues or organs
4. primary habitat of pathogen in the natural world (human, animal, soil, and water).
5. individual or object from which an infection is actually acquired
   Ex: Door knob, roommate, two year old daughter etc.