1. Serological tests
By: Deshanie Govender

2. Classification of antigen-antibody interactions:
Primary serological tests: (Marker techniques) e.g.
Enzyme linked immuono sorben assay (ELISA)
Immuno flurescent antibody technique (IFAT)
Radio immuno assay (RIA)
Secondary serological tests: e.g.
Agglutination tests
Complement fixation tests (CFT)
Precipitation tests
Serum neutralization tests (SNT)
Toxin-antitoxin test
Tertiary serological test: e.g.
Determination of the protective value of an anti serum in an animal.

3. Agglutination tests:
1. Agglutination/Hemagglutination The reaction of an antibody with the antigen can be detected by agglutination (clumping) of the antigen. The general term agglutinin is used to describe antibodies that agglutinate antigens. When the antigen is an erythrocyte the term heamagglutination is used.
a. Qualitative agglutination test Agglutination tests can be used in a qualitative manner to evaluate for the presence of an antigen or an antibody. The antibody is mixed with the particulate antigen and a positive test is indicated by the agglutination of the particulate antigen.

4. For example, a patient's red blood cells can be mixed with antibody to a blood group antigen to determine a person's blood type. In a second example, a patient's serum is mixed with red blood cells of a known blood type to assay for the presence of antibodies to that blood type in the patient's serum.

5. b. Quantitative agglutination test Agglutination tests can also be used to measure the level of antibodies to particulate antigens. In this test, serial dilutions are made of a sample to be tested for antibody and then a fixed number of red blood cells or bacteria or other such particulate antigen is added.

6. 2-Passive hemagglutination: The agglutination test only works with particulate antigens. However, it is possible to coat erythrocytes with a soluble antigen and use the coated red blood cells in an agglutination test for antibody to the soluble antigen. This is called passive hemagglutination.
The test is performed just like the agglutination test. Applications include detection of antibodies to soluble antigens and detection of antibodies to viral antigens.

8. Blood Spatter
Blood Spatter = 2 or more droplets of blood used to reconstruct a series of events surrounding a violent event.

9. BSA can determine Mechanism that created the stains
Direction a blood droplet was traveling
Point/Area of origin
Type of object used in attack
Minimum number of blows
Positioning of the victim, suspect and objects during events
Sequence of events

10. ANGLE OF IMPACT

11. SMOOTH SURFACE ROUGH SURFACE
1) Passive Drops
SMOOTH SURFACE ROUGH SURFACE
EXTRA ROUGH SURFACE

12. Low Velocity Impact (LVI).
Low Velocity Impact (LVI)
Blood Spatter size: large (4 mm +)
Impact velocity: up to 5 feet/sec
Example cause: gravity

13. Medium Velocity Impact (MVI).
Medium Velocity Impact (MVI)
B.S. size: Medium (1 - 4 mm)
Impact velocity (5 to 25 feet/sec)
Example cause: car accident / blunt force trauma

14. High Velocity Impact (HVI)
B.S. size: (1 mm or smaller) Mist like appearance.
Impact velocity: 100 feet/sec and greater.
Example cause: gunshot

15. Arterial Spurting
Bloodstain pattern(s) resulting from blood exiting the body under pressure from a breached artery

16. Determining angles of impact
Angle of impact = direction blood drop(s) was/were traveling
Blood droplets in freefall have the shape of a sphere.
Droplets striking surfaces make it possible to determine the angle at which the droplet struck the surface.