Exam 3 Chapter 37 and 36 Flashcards
1
Q
What is Epidemiology?
A
science that evaluates occurrences, determinants, distribution, and control of health and disease in defined human populations
John snow was the first (studied cholera in london)
Determines:
- causative agent
- source and/or reservoir
- mechanism of transmission
- host and environmental factors
- best control measure
2
Q
Who runs it?
A
USA: Center for Disease Control and Prevention (CDC)
World: World Health Organization (WHO)
3
Q
What is a sporadic disease?
A
occurs occasionally and at irregular intervals
4
Q
What is an endermic disease?
A
maintains a relatively steady low-level frequency at a moderately regular interval
5
Q
What is a hyperendemic disease?
A
gradually increased in occurance frequency above endemic level but not to epidemic level
6
Q
What is outbreak?
A
- sudden, unexpected occurrance of disease
- usually focal or in a limited segment of population
7
Q
What is an epidemic?
A
Sudden increase in frequency above expected number
index case - first case in an epidemic
8
Q
What is pandemic
A
increase in disease occurrance within large population over wide region (usually worldwide)
9
Q
What was the main cause of death around 1900? 2013?
A
1900 = mainy infectious diseasaes (respiratory)
2013 = metabolic / genetic diseases (heart disease and cancer)
10
Q
What is remote sensing and geographical information system used for? Define
A
charting infectious diseases
can be used to study distribution, dynamic and environmental correlates of microbial disease
- Remote sensing (RS) = gathering of digital images of Earth’s surface from satellites and transforming data into maps
- Geographic information system (GIS) = data management system that organizes and displays digital map data from RS
11
Q
What are three important statistical measures of disease frequency to determin if an outbreak, epidemic or pandemic is occuring?
A
- morbidity rate
- # new cases in a time / # individuals in pop.
- prevalence rate = total # infected at one time
- total # of cases in pop / total pop. x 100
- mortality rate
- # deaths due to given disease / pop. size with disease
12
Q
Define infectious disease
A
disease resulting from an infection by microbial agents (bacterial, virus, parasite, fungal)
13
Q
Define communicable disease
A
can be transmitted from one host to another
14
Q
Types of epidemics:
A
- Common source epidemic
- single common contaminated source (food)
- propagated epidemic
- one infected individual into a susceptable gorup, infection propagated to others (strep)
15
Q
What is Herd immunity
A
level of resistance of population to infection and microbe spread because of immunity of large percentage of pop.
16
Q
Level of Herd immunity can be altered by changes in pathogen:… how?
A
- antigenic shift - major change in antigenic character of pathogen
- antigenic drift - smaller antidenic change
17
Q
What is systematic epidemiology?
A
Focuses on ecological and social factors taht influence development and spread of emerging and reemerging disease
numerous factors have been identified
18
Q
Reasons for increases in emerging and reemerging infectious diseases include?
A
- world pop. growth
- increased international travel
- habitat disruption
- microbial evolution and development of resistance
- inadequate public infrastructures
- changes in ecology and climate
- social unrest, wars, and bioterrorism
- chagnes in food processing
- chagnes in human behaviro, techonogy and industry
- mecial practices lead to immunosuppression
19
Q
What is Nosocomial infections?
A
Hospital - acquired
20
Q
What are the sources of Nosocomial infections?
A
- Endogenous pathogen
- exogenous pathogen
- Autogenous infection
21
Q
What is Endogenous pathogen?
A
- brought into hospital by patient or acquired when patient is colonized after admission
22
Q
what is exogenous pathogen?
A
microbiota other than the patient’s
23
Q
What is Autogenous infection?
A
caused by an agent derived form microbiota of patient despite whether it became part of patient’s microbiota following admission
24
Q
What are three types of control measures of epidemics?
A
- reduce or eliminate source or reservoir of infection
- break connection between source and susceptible individual
- reduce number of susceptible individuals
25
How to reduce or eliminate source or reservoir?
* quaratine and isolation of cases and carriers
* destruction of animal reservoir
* treatment of sewage
* therapy that reduces or eliminates infectivity of cases
26
How to break connection between source and susceptible individual?
* Chlorination of water supplies
* pasteurization of milk
* supervision and inspection of food and food handlers
* destruction of insect vectors with pesticides
27
What is reduce number os susceptible individuals?
* raised herd immunity - vaccinations
* passive immunity following exposure
* active immunity for protection
28
What do vaccines do?
attempt to induce antibodies and activated T cells to protect host form futher infection
29
What is Adjuvants?
mixed with antigens in vaccines to enhance the rate and degree of immunization
* can be any nontoxic material that prolongs antigen interaction with immune cells and stimulates the immune response to the antigen
30
When shoudl vaccinations begin?
~2 months, further vaccinations depends on relative risk
31
What are whole cell vaccines?
* Most current vaccines active against bacteria and viruses consist of two microbes that are either inactivated (killed) or attenuated (live but avirulent)
* Considered gold-standard but may be problematic
* may not protect
* immunosuppressed at risk of getting disease
* attenuated may revert to virulent (full pathogen again)
32
Explain Acellular or Subunit Vaccines
* use of purified molecules from microbes avoids some of the risks of whole-cell vaccines
* Forms of subunit vaccines
* capsular polysaccharides
* recombinant surface antigens
* inactivated exotoxins (toxoids)
33
What are recombinant - Vector Vaccines?
Pathogen genes that encode major antigens inserted into nonvirulent viruses or bacteria which serve as vectors and express the inserted gene
- released gene produts (antigens) can elicit cellular and humoral immunity
34
Explain DNA vaccines
* DNA directly introduced into host cell via air pressure or gene gun
* DNA taken into nuclus and pathogen's DNA gragments is expressed
* host immune system responds to foreign proteins produced
* Many DNA vaccine trials are currently being run
35
What are characteristics that favor use of bioterrism?
* invisible, odorless, and tasteless
* difficult to detect
* take hours or days before awareness that they have been used
* fear and panic associated with the anticipation that they were used
36
What are two goals of clinical microbiologists?
1. Rapid and accurate identification of disease-causing microorganism from clinical secimens
2. Accurate antimicrobial susceptibility testing of those isolated organisms
37
Who developed the standard microbiological practices for working with specimens?
Center for Disease Control and Prevention (CDC)
38
Describe the specimen
* Represent diseased area and other appropriate sites
* be large enough for carrying out a variety of diagnostic tests
* be collected in a manner that avoids contamination
* be forwarded promptly to clinical lab
* be obtained prior to administration of antimicrobial agents, if possible
39
Explain the specimin collection:
* specimen shoudl represent the diseased area
* quantity should be adequate
* colleciton to avoid contamination
* proper container, promptly sent to lab
* obtained sepcimen before antimicrobial treatment
40
What are direct measures for identification of microbe?
* growth and biochemical characteristics
* microscopy
* molecular methods
* bacteriophage typing
* immunologic test
41
What are indirect identificaiton methods?
* Serology
* immunofluorescence
42
Explain grwoth and biochemical characteristics
* Tequniques used depend on nature of pathogen
* for some pathogens, culture-based techniques have limited use
43
What can culturing bacteria provide?
preliminary infroamtion about biochemical nature of bacterium
- some bacteria are not routinely cultured
(ricketsias, chlamydiae, and mycoplasmas)
identified with special stains, immunologic tests, or molecular methods such as PCR
44
Explain parasite techniques
culture- based techniques not commonly used
45
What can be viewed under microscope? describe methods
* Viewed:
* bacteria, fungi, viruses, parasites
* Method:
* Wet-mount, heat-fixed or chemically fixed with stains often used
46
Explain monoclonal antibodies (mAb)
* Produced by hybridoma cells
* Recognize a single epitope
* fluorescently - labeled mAbs used diagnostically
* technique has replaced use of polyclonal antisera for culture confirmation (polyclonal= very advanced system needed)
47
Explain immunofluorescence
* Process in which fluorescent dyes are exposed o UV, violet or blue light to make them fluoresce
* Dyes coupled to antibody molecules
* can be direct or indirect fluorescent antibody technique
48
Explain parasite identification methods
* Identification by microscopic examination of clinical specimens
* diagnosis obtained by identification and characterization of ova (egg), trophozoites (life) and cysts (hyphenating state) in the specimen
49
What are molecular methods?
* Accurate, routine, used in clinical microbiolgy labs
* comparison of proteins
* Nucleic acid-based detection methods (DNA)
* Widely used tests include:
* Nucleic acid probes; DNA hybridization
* PCR and real time PCR
* ribotyping (based on high level of 16S rRNA)
* multilocus sequence typing
* genomic fingerprinting
* plasmid fingerprinting (# and MW)
50
Explain clinical immunology
* Number, sensitivity, and specificity of serological tests increased due to better understanding of:
* Immune cell surface antigens (CDs)
* lymphocyte biology
* production of monoclonal antibodies
* development of sensitive antibody-binding reporter systems
* Test selection and timging of specimen collection are essential to the proper interpretation of immunologic tests
51
Explain Serotyping
Use of serum antibodies to detect and identify other molecules
can be sued to differentiate serovars or serotypes of microbes taht differe in antigenic composition of structure or product
52
Explain Agglutination
visible clumps or aggregates of cells or particles
ie. rapid plasma reagin test (diagnostic for syphilis)
latex agglutination test (HIV diagnosis, viral hemagglutination)
antibody titer measurements
53
Explain complement fixation
* Binding of complement to an antigen-antibody complex
* basis of diagnostic tests that determine if antibodies to an antigen are present in patients serum
* very sensitive, measures extremely small amounts of antiboides
54
Explain Enzyme-Linked Immunosorbent Assay (ELISA)
* One of the most widely used serological tests
* direct test can be used to detect antigens in a sample
* indirect test can be used to detect antibodies in a sample
* Reaction visualized by addition of chromogen (adds color)
* Example = home preganancy test
55
Explain Immunoblotting (Western Blotting)
* Procedure
* Proteins separated by electrophoresis
* protein bands visualized with enzyme-tagging antibodies
* Samples used include
* distinguish microbes
* diagnostic tests
* prognosis of infection
56
Explain immunoprecipitation test
* Detects soluble Ag reacting with Ab (precipitins)
* Binding of Ab to Ag forms lattice that precipitates
* Lattice formation occurs only in optimal ratio of Ag to Ab
57
Explain immuno diffusion test
* Precipitation reaction that occurs in agar gel media
* two commonly used techniques
* Single radial immunodiffusion (RID) assay (antibody in agar antigen diffuses)
* Guantitates antigen
* Double diffusion agar assay (ouchterlony technique)
* antibody and antigen both diffuse
* identifies antigens
58
Expain Immunoelectrophoresis
* Antigen first separates by electrophoresis accoring to charge
* antigens visualized by precipitation reaction
* has greater resolution than immunodiffusion assay
59
Explain Flow cytometry
* Detects organisms in clinical samples
* Detection based on cytometric parameters or by use of fluorochromes
* fluorochromes often bound to antibodies or oligonucleotides
* Forces suspension of cells through laser beam and measure amount of light scattering of fluorescence
* can detect heterogeneous microbial populations with different responses to antimicrobial treatments
* USE SURFACE MARKERS TO IDENTIFY SPECIFIC ITEMS
60
What is Radioimmunoassay (RIA)
* Purified antigen labeld with radioisotope competes with unlabeled standard for antibody binding
* Amount of radioactivity associated with antibody is measured
* Usualy Iodine 125 as it is easy to work with
