Chapter 9 continued

Question 1

Bacteria

Answer 1

Prokaryotic, unicellular

• some are obligate intracellular parasites some are free living
  ex: streptococcal, staphylococcal, tetanus, pneumonia, typhus

Question 2

Viruses

Answer 2

Noncellular, nonliving, infectious particles

• contain DNA/RNA
• smaller than prokaryotes
  ex: AIDS, influenza, hepatitis, polio, smallpox

Question 3

Prions

Answer 3

infectious proteins

• NOT cells
• no DNA/RNA
• cause certain proteins in host brain to fold incorrectly
  ex: CJD, Kuru, chronic wasting disease (elk,deer,moose)

Question 4

disease source

Answer 4

the person, animal, object, or substance that disseminates/passes the infectious agent to the host
-can be the same as reservoir

Question 5

Reservoir

Answer 5

animate/inanimate habitat that the infectious pathogen is naturally found in.

Question 6

Endogenous Source

Answer 6

infectious pathogen came from host’s own body
ex: misplaced microbiota (skin microbiota entering through wound)
disrupted microbiota & opportunistic pathogens (vaginal yeast infection)

Question 7

exogenous source

Answer 7

pathogen came from source external to host’s own body

• Environmental: contaminated food/water, soil, med equipment
• Animals: zoonotic disease spread to human
• Humans: communicable diseases

Question 8

Disease transmission

Answer 8

how the pathogen is spread to the host

Question 9

Direct contact transmission

Answer 9

host physically comes into contact with the source of pathogen

• person-person: saliva, touching, sex
• animal-person: bite, scratch, zoonotic
• environment-person: swimming, soil
• Vertical: mother to child in utero, breastmilk, vaginal delivery

Question 10

indirect contact transmission

Answer 10

pathogen spreads with out host’s direct physical contact to the source

• airborne: pathogen enters through respiratory route
• vehicle: pathogen introduced through host’s contact to contaminated object
• biological vector: part of pathogen’s lifecycle is in an animal and other part in human (mosquito bite, tick bite)
• mechanical vector: pathogens lifecycle is outside host and it catches a ride( roaches,flies)

Question 11

5 stages of infectious disease

Answer 11

1. incubation period
2. prodromal
3. acute
4. decline
5. convalescence

Question 12

incubation period

Answer 12

time of exposure to infectious pathogen til the 1st sign of symptoms

• varies by person
• varies by pathogen
• challenging to determine incubation time due to variables
• disease can spread

Question 13

prodromal period

Answer 13

early symptoms/signs develop

• mild symptoms/signs due to activation of immune system
• pathogen continues multiplying
• infection can still be spread

Question 14

Acute period

Answer 14

full experience of signs/symptoms

• symptomatic
• asymptomatic
• some diseases that are asymptomatic on one host can be deadly in another

Question 15

Decline period

Answer 15

pathogen replication decreases

• host begins to feel better
• patients usually stop antibiotics during this period causing the infection to return full force or the pathogen to mutate and become antibiotic resistant

Question 16

Convalescence Period

Answer 16

pathogen is usually eliminated at this stage but can be kept latent in the host’s body (usually viruses)
-disease can reactivate at a later time if latent in the body

Question 17

chronic carrier

Answer 17

mostly asymptomatic with sporadic recurrences

-can infect others ( HSV2)

Question 18

asymptomatic carrier

Answer 18

pathogen stays latent in carrier showing no symptoms

-can infect others (streptococcus pyrogenes)

Question 19

epidemiology

Answer 19

“the study of what is upon the people”
Hippocrates wat the 1st epidemiologist
-understand and prevent illness in communities

Question 20

Goals of epidemiology

Answer 20

1. describe the nature, cause, and extent of new/existing diseases in populations
2. intervene to protect and improve health in populations

Question 21

examples of host factors in epidemiological triangle

Answer 21

general health, sex, lifestyle, age, ethnicity, occupation

Question 22

examples of environmental factors in epidemiological triangle

Answer 22

climate, geographical location, availability of transmitting vector, water source, food source

Question 23

how can epidemiological triangle be broken

Answer 23

education, quarantine, vector control

Question 24

roles of public health

Answer 24

investigates, diagnoses, prevents, and works to reduce health related problems in community

Question 25

rate

Answer 25

measures occurrence of an event over time

Question 26

ratio

Answer 26

presents the occurrence of one group compared with another group
ex: in US the people age 65^ are 0.77male/female

Question 27

proportion

Answer 27

a percentage of a whole

ex: 80 out of 100 women/80% of women with gonorrhea are asymptomatic

Question 28

why are epidemiological measurements useful

Answer 28

they provide insight as to where public health campaigns or prevention efforts are needed most

Question 29

measures of frequency

Answer 29

gives information about occurrences of a disease in a population during a certain period of time

• reveals degree of morbidity (existence)
• prevalence rate

Question 30

prevelance rate

Answer 30

describes morbidity in a given population during a specific time

• total # of cases in a given time divided by total #of people in the defined population during that same time
• not a measure of how dangerous the disease is
• impacted by incidence rate and duration

Question 31

incidence rate

Answer 31

the number of new cases in a defined population during a defined time frame
-new cases in a defined pop during specific time divided by susceptible hosts in the population during the same time

Question 32

duration

Answer 32

how long the infection lasts

Question 33

morbidity

Answer 33

existence of the disease

Question 34

measures of association

Answer 34

tell what factors may be linked with cases of the disease showing who may be at risk for developing an illness.

• helps providers diagnose correctly for patients showing general signs/symptoms
  ex: pt living in certain area presents with joint pain and fatigue, doc will ask if pt spends much time outdoors or noticed any tick bites bc Lyme disease is associated with tick bites

Question 35

mortality rate

Answer 35

most common association measure

-the number of deaths during a specific time period

Question 36

crude mortality

Answer 36

general death rate in a population, not determined based on specific causes of death

Question 37

cause-specific mortality rate

Answer 37

deaths due to a specific cause, in a given population, during a specified period

Question 38

infant mortality rate

Answer 38

death rate of children under age 1, as compared to number of live births

Question 39

maternal mortality rate

Answer 39

maternal deaths per 100,000 live births, from any cause related to pregnancy or management of pregnancy

Question 40

case fatality rate

Answer 40

percentage of people with a particular diagnosis who die in a specified time period after diagnosis

Question 41

correlation does not imply causation

Answer 41

just because 2 things occur around the same time or place doesn’t make the variables correlated or linked
ex: autism spikes and vaccines

Question 42

descriptive epidemiology

Answer 42

who is infected, where cases occur, and when cases occur
-goal is to describe occurrence/distribution of disease so a hypothesis about causes, prevention, treatment can be developed and tested

Question 43

analytical epidemiology

Answer 43

investigates what caused the disease, why people get it, and how to prevent or treat the disease