Midterm2

Question 1

What are Kochs postulates used for?

Answer 1

To prove the cause of an infectious disease

Question 2

Kochs postulates

Answer 2

1) The same pathogen must be present in every case of the disease
2) The pathogen must be isolated from the disease host and grown in pure culture
3) the pathogen from the pure culture must cause the disease when it is 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 3

Incidence

Answer 3

Describes the rate of development of a disease in a group over a period of time; new cases
♣
(Number of persons develop a disease/ total number at risk)*unit time

Question 4

Prevalence

Answer 4

♣ Count of the # of person w/ disease
- Is the most frequently used measure in epidemiology
♣ New and old cases
(# of persons w/ a disease/total # in grp

Question 5

Morbidity rate

Answer 5

o incidence of illness (disease) in a population. It includes both fatal and nonfatal diseases; could refer to either prevalence or incidence

Question 6

Mortality rate

Answer 6

Incidence of death in a population

♣ (# of persons dead/ total # in grp)x unit time

Question 7

Case fatality rate

Answer 7

the number of confirmed cases that died of the disease

Question 8

Sporadic disease:

Answer 8

disease that occurs only occasionally

Question 9

Endemic disease

Answer 9

disease constantly present in a population

Question 10

Epidemic disease

Answer 10

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

Question 11

Pandemic disease

Answer 11

worldwide epidemic

Question 12

Acute disease

Answer 12

symptoms develop rapidly but the disease lasts only a short time

Question 13

Chronic disease

Answer 13

symptoms develop slowly

Question 14

Subacute disease

Answer 14

intermediate btw acute and chronic

Question 15

Latent disease

Answer 15

causative agent is inactive for a time but then activates and produces symptoms

Question 16

Herd immunity

Answer 16

immunity in most of a population

Question 17

Case definition

Answer 17

important and not trivial

Question 18

Local infection

Answer 18

pathogens are limited to a small area of the body

Question 19

Systemic (generalized) infection

Answer 19

an infection throughout the body

Question 20

Focal infection

Answer 20

systemic infection that began as a local infection

Question 21

Sepsis

Answer 21

Toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins from a focus of infection

Question 22

Bacteremia

Answer 22

bacteria in the blood

Question 23

Septicemia

Answer 23

also known as blood poisoning growth of bacteria in the blood

Question 24

Toxemia

Answer 24

toxins in the blood

Question 25

Viremia

Answer 25

viruses in the blood

Question 26

Primary infection

Answer 26

acute infection that causes the initial illness

Question 27

Secondary infection

Answer 27

opportunistic infection after a primary infection

Question 28

Subclinical disease

Answer 28

no noticeable signs or symptoms

Question 29

Predisposing factors (make the body more susceptible to disease)

Answer 29

o	Gender
o	Inherited traits such as the sickle cell gene
o	Climate and weather
o	Fatigue
o	Age
o	Lifestyle 
o	Nutrition
o	Chemotherapy

Question 30

• Development of Disease

Answer 30

o Incubation period: interval btw initial infection and first signs and symptoms
o Prodromal period: short period after incubation; early, mild symptoms
o Period of illness: disease is most severe
o Period of decline: signs and symptoms subside
o Period of convalescence: body returns to its pre-diseased state

Question 31

o Human reservoirs

Answer 31

♣ Carriers may have unapparent infections or latent diseases
♣ By vaccinating youre changing the dynamic of sideade and provide immunity for the community
♣ Influenza virus that are similar enough to humans can sometimes make that cross

Question 32

Animal reservoirs

Answer 32

Zoonoses are diseases transmitted from animals to humans

Question 33

Nonliving reservoirs

Answer 33

♣ Soil and water

Food

Question 34

Transmission

Answer 34

o Direct contact: requires close association btw the infected and a susceptible host
o Indirect contact: spreads to a host by a nonliving object called a fomite
o Droplet transmission: transmission via airborne droplets less than 1 meter (sneeze)
o Vehicle: transmission by an inaminate reservoir
♣ Waterborne, foodborne, airborne

Question 35

Healthcare-associated infections

Answer 35

o Acquired while receiving treatment in a health care facility
♣ Also known as nosocomial infections

Question 36

Emerging infectious diseases

Answer 36

diseases that are new, increasing in incidence, or show a potential to increase in the near futues

most zoonotic
of vital origin
likely vector borne

Question 37

• Centers for Diesease control and prevention (CDC)

Answer 37

o Collects and analyzes epidemiological information in the US
o Morbidity and Mortality Weekly Report
o Notifiable infectious disease: diseases In which physicians are required to report ocurrence

Question 38

Molecular strain-typing techniques; when to use

Answer 38

♣ Simplicity – simpler to execute and simpler to trainpeople to use(e.coli in brazil 1 month v 6)
♣ High throughput – capacity of tet to process a large number of specimens simultaneously
♣ Cost- widespread use of molecular bio reagents reduced costs. PCR have all the same reagents except for primers
♣ Appropriateness –
• The capacity of a test to addres epidemiologic problems not possible to address by conventional methods
• If conventional test possible then no need
• Often DNA sequences allow unambiguous identification of new ingectious agents and evolution of these agents

Question 39

Molecular strain-typing techniques; how to select

Answer 39

♣ Typeabiliy: ability of a technique to generate an unambiguous result for an isolated test
♣ Reproducibility : ability to produce identical results
♣ Ease of interpretation: serve as stratum
♣ Ease of use: simplicity
♣ Stability: character us no subject to rapid evolution or lost from host
♣ Epidemiologic concordance: effectively group outbreak related strains
♣ Typing system concordance: molecular typing compares favorably with a previously validated test
♣ Validity: correctly predict or identify those who truy have the characteristics