Question

5. Explain the rapid diagnostic test, the ELISA, or the neutralization test. What are the pros and cons of each test?

Answer 1

• Answer:
• RAPID DIAGNOSTIC TEST: RDT can speed the diagnosis of various infections in emergency settings such as sepsis, respiratory tract infections and meningitis.
• RDT for malaria is also available - it is an immunochromatograohic test which is used to detect specific antigens on malarial parasite.
• Antigens of malarial parasite that are currently targeted are Histidine Rich Protein II and parasite lactate dehydrogenase (LDH).
• PROS: - Rapid diagnosis can be made.

​​​​​​ - Useful in emergency situations.

- Highly specific and sensitive.

• ​​​​​​CONS: - RDT may not be able to detect small number of infectious agent present in blood.

- No distinction between new and treated infection.

• ELISA: Enzyme linked immunosorbent assay.
• Principle- It helps in detection of an antigen in the test sample by enzyme linked antibody for that antigen and then substrate is added. Results are interpreted on the basis of colour change on addition of substrate.
• Types of ELISA: Direct ELISA, Indirect ELISA, Competitive ELISA and Sandwich ELISA.
• Pros: Highly specific and sensitive.
• Easy to perform and quick.
• Reagents are relatively cheap and have a long shelf life.
• Cons: Enzyme activity may be affected by plasma constituents.
• False positives / False negatives are possible.