Diagnosis of Viral Infections (Ex1) Flashcards
1
Q
Risk Group 1
A
- no or low individual and community risk
- a microbe that is unlikely to cause human or animal disease
2
Q
Risk Group 2
A
- moderate individual risk, low community risk
- a pathogen that can cause human or animal disease, but unlikely to be a serious hazard
- effective treatment and preventative measures available
3
Q
Risk Group 3
A
- high individual risk, low community risk
- a pathogen that usually causes serious human or animal disease, but does not normally spread
- effective treatment and preventative measures available
4
Q
Risk Group 4
A
- high individual and community risk
- pathogen that usually causes serious human or animal disease and is readily transmitted
- no effective treatment or preventative measures
5
Q
Negative Stain Electron Microscopy
A
- sample mixed with solution of heavy metal salt that is opaque to electrons
- spread on thin layer of copper grid
- stain absorbs electrons through beam
- virus particles appear lucent
6
Q
Scanning Electron Microscopy
A
- method based on scattered electrons
- focuses on sample surface and its composition
- 3D images
7
Q
Transmission Electron Microscopy
A
- method based on transmitted electrons
- focuses on inside or beyond surface
- images have higher magnification and greater resolution
- 2D images
8
Q
What is Negative Predictive Value?
A
the probability that a negative test result accurately indicates the absence of infection
9
Q
What is Positive Predictive Value?
A
the probability of a positive result accurately indicating presence of infection
10
Q
What is Sensitivity?
A
the probability that cases with the infection will have a positive result
11
Q
What is Specificity?
A
the probability that cases without the infection will have a negative result
12
Q
Describe a Direct ELISA test
A
- suspected virus sample
- add enzyme conjugated antibodies
- if antibodies bind to antigens, color change noted
13
Q
Describe an Indirect ELISA test
A
- sample with known antigen
- add patient sample
- if patient has antibodies they will bind
- add secondary antibody with enzyme that binds to the primary antibody
14
Q
Describe a Sandwich ELISA test
A
- antigen to be measured is bound between a layer of capture antibodies and detection antibodies
15
Q
Describe Competitive ELISA test
A
- antigen of interest and purified antigen compete for binding to capture antibody
