Flashcards in Lecture 14 - Diagnostic Microbiology and Epidemiology Deck (35)
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
How do we classify disease?
-restricted areas and low incidence
-restricted areas and high incidence
-worldwide and high incidence
What is incidence vs prevalence?
-number of new cases
-record of disease spread
-Number of new and existing cases
-record of total disease burden
Faucet and bathtub example
What is mortality and morbidity?
-incidence of death
-fatal cases only
-Incidence of disease
-fatal and nonfatal cases
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
How do pathogens live?
-grow/reproduce only in host
-cause chronic infections
-grow/reproduce outside of the host
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
Where do pathogens live?
-Where they can reproduce, grow, and spread
-Animate = living like lymes disease and ticks
-Inanimate = nonliving like soil
How is disease transmitted?
-person to person = human to human
-zoonosis = non-human to human, human dead-end host
-Vectors = reservoir to human using living carrier
-vehicles = reservoir to human using nonliving carrier
What are the different types of epidemics?
-Inanimate Reservoirs like contaminated water
-quick increase/decrease in number of cases
-Animate Reservoirs like influenza
-longer duration but lower number of cases
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
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
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
How do we calculate the basic reproductive number, R0?
R0 = r*c*d
c=avg rate of contact between ppl
d=duration of infectious stage
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
What public health measures do we take to identify, track, contain and eradicate infectious disease?
1. Control against vehicles
2. Control against reservoirs
How do we control against vehicles?
-HVAC and air masks
How do we control against reservoirs?
-vaccination programs at vet
-bait traps and oral vaccines
How do we use immunization in disease management?
Highly controlled Child Immunization
Booster shots for adult immunization
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
How do we use surveillance in disease management?
Monitor disease incidence and prevalence
-apply disease tracking data
-implement control strategies
CDC in U.S.
What are emerging diseases and what are the types?
Sudden increase in disease prevalence
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
What is biological warfare?
Use of biological agents to kill/incapacitate
-easy to produce/deliver
What is diagnostic microbiology? What are the techniques of diagnostic microbiology?
detection, identification, and characterization of infectious disease
3. Molecular, DNA/RNA
What is the key to diagnostic microbiology?
-ability to recognize single pathogen strain
-no false positives
-Lowest amount of pathogen cells detected
-highest sensitivity=1 pathogen cell
What are the culturing techniques used in diagnostic microbiology?
-only target microbe will grow
-more than one microbe grows but media allows you to tell the difference
How do we determine susceptibility of pathogen using culturing techniques?
-disc diffusion and minimum inhibitory concentration
-periodic reports of pathogen resistance
What are immunoassays used for? What are the types?
detect specific pathogens/pathogen products
-no culture needed
-uses pathogen-specific antibodies
Types of Immunoassays