Lecture 14 - Diagnostic Microbiology and Epidemiology Flashcards Preview

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Flashcards in Lecture 14 - Diagnostic Microbiology and Epidemiology Deck (35)
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1

What is epidemiology?

Study of the Occurrence, Distribution and Determinants of Health and Disease
-Focuses on Public Health
-Health of the Human Population as a Whole

2

How do we classify disease?

Endemic
-restricted areas and low incidence

Epidemic
-restricted areas and high incidence

Pandemic
-worldwide and high incidence

3

What is incidence vs prevalence?

Incidence
-number of new cases
-record of disease spread

Prevalence
-Number of new and existing cases
-record of total disease burden

Faucet and bathtub example

4

What is mortality and morbidity?

Mortality
-incidence of death
-fatal cases only

Morbidity
-Incidence of disease
-fatal and nonfatal cases

5

What do we look at when we are trying to control and eradicate disease?

How do they live

Where do they live

How are they transmitted

6

How do pathogens live?

Host-Dependent
-grow/reproduce only in host
-cause chronic infections

Host-Independent
-grow/reproduce outside of the host
-acute infections

7

What are the stages of disease progression in acute infections?

Infection - pathogen invades, colonizes
Incubation Period - pathogen grows, no symptoms
Acute Period - appearance of symptoms
Decline Period - decline of symptoms
Convalescent Period - host recovery

8

Where do pathogens live?

Disease reservoirs
-Where they can reproduce, grow, and spread

Types
-Animate = living like lymes disease and ticks
-Inanimate = nonliving like soil

9

How is disease transmitted?

Direct Host-to-Host
-person to person = human to human
-zoonosis = non-human to human, human dead-end host

Indirect Host-to-Host
-Vectors = reservoir to human using living carrier
-vehicles = reservoir to human using nonliving carrier

10

What are the different types of epidemics?

Common-Source Epidemics
-Inanimate Reservoirs like contaminated water
-quick increase/decrease in number of cases

Host-to-Host Epidemics
-Animate Reservoirs like influenza
-longer duration but lower number of cases

11

What are the types of host-pathogen coevolution?

Selection pressures for mutual coexistence
-common for host-dependent pathogens
-decreased pathogen virulence and increased host resistance

No selection pressures for mutual coexistence
-common for host-independent pathogens
-pathogen virulence remains high but host resistance remains low

12

What are nosocomial infections?

Infections acquired by patients in hospitals

Selects for highly virulent, antibiotic resistant pathogens - host independent
-Low host resistance
-Many pathogen reservoirs
-Breaching of skin barrier
-Drug usage = antibiotic resistance

13

What is the Basic Reproductive Number R0?

Number of secondary cases from an infected individual
-how many ppl you transmit disease to
-R0<1, disease will die out
-R0=1 disease is maintained
-R0>1, disease outbreak, possible epidemic

14

How do we calculate the basic reproductive number, R0?

R0 = r*c*d

r=transmissibility
c=avg rate of contact between ppl
d=duration of infectious stage

15

What is herd immunity?

Prevent epidemics by limiting pathogen transmission
-the immune individuals protect pl w/o immunity
-increase pathogen virulence = more immune ppl needed to prevent epidemic

16

What public health measures do we take to identify, track, contain and eradicate infectious disease?

Disease Management
1. Control against vehicles
2. Control against reservoirs
3. Immunization
4. Quarantine
5. Surveillance

17

How do we control against vehicles?

Water Purification

Food purity/preparation
-pasteurization

Air Filtration
-HVAC and air masks

18

How do we control against reservoirs?

Domestic Animals
-vaccination programs at vet

Wild Animals
-bait traps and oral vaccines

Insect vectors
-insecticides

19

How do we use immunization in disease management?

Highly controlled Child Immunization

Booster shots for adult immunization

20

How do we use quarantine in disease management?

Restricted movement of disease carriers
-prevent spread of highly contagious disease

Human and Animal Quarantine
-humans w/ active infections
-animals that are disease vectors

21

How do we use surveillance in disease management?

Monitor disease incidence and prevalence
-apply disease tracking data
-implement control strategies

CDC in U.S.
WHO internationally

22

What are emerging diseases and what are the types?

Sudden increase in disease prevalence

Types
-New Diseases
-Reemerging diseases

23

What are the factors of disease emergence?

1. Human demographics and behavior
2. Economic Development and land use
3. International travel
4. Pathogen adaptation
5. Loss of health standards

24

What is biological warfare?

Use of biological agents to kill/incapacitate

Characteristics
-easy to produce/deliver

Delivery
-aerosol
-drinking water
-food

25

What is diagnostic microbiology? What are the techniques of diagnostic microbiology?

detection, identification, and characterization of infectious disease
-clinical microbiology

Techniques
1. Culturing
2. Immunoassays
3. Molecular, DNA/RNA

26

What is the key to diagnostic microbiology?

Specificity
-ability to recognize single pathogen strain
-no false positives

Sensitivity
-Lowest amount of pathogen cells detected
-highest sensitivity=1 pathogen cell

27

What are the culturing techniques used in diagnostic microbiology?

Selective Media
-only target microbe will grow

Differential Media
-more than one microbe grows but media allows you to tell the difference

28

How do we determine susceptibility of pathogen using culturing techniques?

Antibiotic tests
-disc diffusion and minimum inhibitory concentration

Antibiograms
-periodic reports of pathogen resistance
-nosocomial pathogens

29

What are immunoassays used for? What are the types?

detect specific pathogens/pathogen products
-no culture needed
-uses pathogen-specific antibodies

Types of Immunoassays
-Immunofluorescence
-ELISA

30

What is the immunoassay type, immunofluorescence?

Label antibodies with fluorescent tag
Light emitted when antibodies bind
Early detection in vivo