Parasite Serology

Question 1

Antigen capture serology and ELISA, how do they work?

Answer 1

Use antigen in the lab
Add patients sample which contains antibody
Positive when bind - light up

Question 2

How does agglutination tests work? (also known as an ELISA like assay)

Answer 2

Coat erythrocytes with antigens
Test antibody added (patients sample)
Agglutination in the presence of antibodies

Question 3

Immunoblotting? Western Blot

Answer 3

Antigens in lab are bound to bands
Add patients sample
If antibody present ->bands which turn colour

Question 4

Immunodiffusion assay?

Answer 4

Western Blot on a slide

Question 5

ELISA assays/haemaglutination disadvantage?

Answer 5

Low incidence setting - most will be false positives!!

Good sensitivity
Poor specificity

Question 6

Westen blot assay?

Answer 6

Excellent specificity
Limited sensitivity

Question 7

Antigen detection assays?

Answer 7

Good sensitivity

Question 8

PCR assays?

Answer 8

Superb sensitivity and specificity

Question 9

What is the problem with normal ranges for serology testing?

Answer 9

Normal range set at 2 standard deviations
2.5% of true negatives will be false positives