Ch 14 Study Guide Principles of Disease and Epidemiology

Question 1

Etiology

Answer 1

cause of disease

Question 2

Pathogenesis

Answer 2

manner in which disease develops

Question 3

Infection

Answer 3

invasion or colonization of the body by a pathogenic microbe

Question 4

Disease

Answer 4

infection results in any change from a state of health
- Part or all of the body is incapable of performing its normal functions

Question 5

Communicable disease

Answer 5

disease that is spread from one host to another

Question 6

Noncommunicable disease

Answer 6

a disease that is not spread from one host to
another.
Ex. Tetanus (Clostridium tetani)

Question 7

Symbiosis

Answer 7

is the relationship between normal microbiota and the
host

Question 8

Commensalism, example?

Answer 8

one organism benefits, and the other is unaffected

ex: bacteria on the skin

Question 9

Mutualism, example?

Answer 9

both organisms benefit

ex” bacteria in stomatch

Question 10

Parasitism, example?

Answer 10

one organism benefits at the expense of the other

ex: tape worm

Question 11

Is this typical of subacute, chronic, or acute infection?

The patient experiences a rapid onset of malaise; symptoms last 5 days.

Answer 11

Acute

Question 12

Is this typical of subacute, chronic, or acute infection?

The patient experiences cough and breathing difficulty for months.

Answer 12

chronic

Question 13

Is this typical of subacute, chronic, or acute infection?

The patient has no apparent symptoms and is a known carrier.

Answer 13

subacute

Question 14

Among hospital patients who have infections, one-third do not enter the hospital with the infection but rather acquired it in the hospital. How do they acquire these infections?

Answer 14

Hospital patients may be in a weakened condition and therefore predisposed to infection

Question 15

What is the method of transmission of these hostpital infections?

Answer 15

Pathogenic microorganisms are generally transmitted to patients by contact and airborne (indirect) transmission

Question 16

What is the reservoir of infection for these hospital infections?

Answer 16

The reservoir of infection is the hospital staff, staff and other patients.

Question 17

Distinguish symptoms from signs as signals of disease.

Question 18

How can a local infection become a systemic infection?

Answer 18

An infection that is spread through the bloodstream

Question 19

Why are some organisms that constitute the normal microbiota described as commensals, whereas others are described as mutualistic?

Answer 19

Mutualistic microorganisms are providing a chemical or environment that is essential for the host.

Commensal organisms are not essential; another microorganism might serve the function as well.

Question 20

Put the following in the correct order to describe the pattern of disease: period of convalescence, prodromal period, period of decline, incubation period, period of illness.

Answer 20

1) Incubation period
2) Prodromal period
3) Illness period
4) Decline period
5) Convalescence period

Question 21

Normal microbiota

Answer 21

permanently colonize the host and do not cause disease
under normal conditions

Question 22

How do people acquire normal microbes (human microbiome)

Answer 22

during birth and the first years of life. They’re acquired from food, people and pets.

Question 23

What are three ways normal microbes are beneficial to us?

Answer 23

1. Competing for nutrients with other microbes
2. Producing substances that are harmful to invaders
3. Affecting the environment, pH or available oxygen to keep invaiders away

Question 24

opportunistic pathogen

Answer 24

do not cause disease in their normal habitat in a
healthy person but may do so in a different environment

Question 25

What can allow opportunistic pathogens to cause disease?

Answer 25

when the pathogen is displaced in an unusual location or the host has a weakened immune system

Question 26

What are Koch's 4 postulates?

Answer 26

1. The same pathogen must be present in every case of the disease. 2. The pathogen must be isolated from the diseased host and grown in pure culture. 3. The pathogen from the pure culture must cause the disease when it’s inoculated into a healthy, susceptible laboratory animal. 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

Question 27

What are some important exceptions to Koch’s postulates?

Answer 27

1. Some diseases caused by a variety of microbes 2. Some pathogens can cause several disease conditions 3. Some pathogens cause disease only in humans (would be unethical to test in humans) 4. Some microbes have never been cultured

Question 28

Whats Koch's 1st Postulates?

Answer 28

1. The same pathogen must be present in every case of the disease.

Question 29

Whats Koch's 2nd Postulate?

Answer 29

2. The pathogen must be isolated from the diseased host and grown in pure culture.

Question 30

Whats Koch’s 1st exception?

Answer 30

1. Some diseases are caused by a variety of microbes

Question 31

Whats Koch’s 2nd exception?

Answer 31

2. Some pathogens can cause several disease conditions

Question 32

Know what theory from chapter 1 Koch’s work is related to.

Answer 32

Germ theory of disease

Question 33

How is a symptom distinct from a sign?

Answer 33

- Symptoms are subjective and can be perceived only by the person affected. - Signs are objective findings that can be seen or measured

Question 34

What makes a communicable disease contagious?

Answer 34

From one host to another

Question 35

Be able to define endemic disease.

Answer 35

disease constantly present in a population

Question 36

How does an endemic disease become an epidemic?

Answer 36

disease acquired by many people in a given area in a short time

Question 37

Know the difference between acute and chronic diseases.

Answer 37

Acute illnesses generally develop suddenly and last a short time Chronic conditions develop slowly and may worsen over an extended period of time—months to years

Question 38

Which term is used to describe a disease that is dormant because the microorganism is inactive?

Answer 38

Latent disease

Question 39

How would you describe a subclinical infection?

Answer 39

no noticeable signs or symptoms, but infection is present and person can be infectious

Question 40

During which periods is the number of microorganisms increasing?

Answer 40

incubation period Prodromal period

Question 41

In which period does death most likely occur?

Answer 41

Period of illness

Question 42

In which period does a secondary infection most likely set in?

Answer 42

Period of decline

Question 43

Is a person pathogen free during any of the periods?

Answer 43

No

Question 44

What is the difference between the reservoirs?

Answer 44

- HUamn reservoirs invole human carriers - Animal reservoirs involve animals as carriers - Non-living reservoirs involve non-living things such as soil and water

Question 45

What are zoonoses?

Answer 45

are diseases transmitted from animals to humans

Question 46

How do we acquire zoonoses?

Answer 46

Direct contact: Coming into contact with the saliva, blood, urine, mucous, feces, or other body fluids of an infected animal. Examples include petting or touching animals, and bites or scratches.

Question 47

What are the three forms of contact transmission?

Answer 47

- Direct contact: person to person - Indirect contact: transferred by a nonliving object. (FOMITE) ex. syringes - Droplet: microbes spread in mucus droplets. Ex: sneeze; 20k droplets.

Question 48

What are the three forms of vehicle transmission?

Answer 48

- Air: microbes traveling more than 1 meter attached to dust particles - Water: untreated or poorly treated sewage - Food: food imporoperly cooked, poorly refrigerated, unsanitary conditions

Question 49

You should be able to cite many examples of fomites (Indirect contact transmission)

Answer 49

Stethoscopes, tissues, bedding, towels etc. - Contaminated syringes (AIDS and hepatitis B)

Question 50

What is the difference between a biological and a mechanical vector?

Answer 50

Mechanical transmission: passive transport (pathogens on the insect’s feet or other body parts) Biological transmission: active process (bug bites)

Question 51

What is a nosocomial infection?

Answer 51

healthcare-associated infections

Question 52

What 3 factors contribute to nosocomial infections?

Answer 52

1. Microorganisms in the hospital environment 2. Weakened (compromised) status of the host 3. Chain of transmission in a hospital

Question 53

What are some examples of microbes that cause nosocomial infections

Answer 53

E.coli, S. aureus, Klebsiella species, Enterobacter species, Enterococcus species, Streptococcus species, Coagulase-negative Staphylococcus

Question 54

Know the epidemiological studies talked about in lecture

Answer 54

John Snow: Mapped the occurance of cholera in London Ignaz Semmelweis: Showed that handwashing decreased the incients of sepsis Florance Nightingale: Showed that improved sanitation decreased the incidents of epidemic typhus

Question 55

Explain 3 ways bacteria damage host cells

Answer 55

1. Direct damage (viruses lysing host cells) 2. Producing toxins 3. Using the hosts nutrients

Question 56

The prodromal period occurs prior to..

Answer 56

Illness