Question
Diagnosis of filariasis is confirmed most commonly by-
| A. | Clinical features |
| B. |
Detection of microfilariae |
| C. |
PCR |
| D. |
Serological test |
Show Answer
|
Correct Answer » B Explanation |
 |
The definitive and most commonly used method for confirming lymphatic filariasis is the demonstration of microfilariae in peripheral blood.
- Microfilariae are detected by microscopic examination of peripheral blood smears.
- Since Wuchereria bancrofti and Brugia malayi exhibit nocturnal periodicity, blood should ideally be collected between 10 PM and 2 AM.
- Concentration techniques such as the Knott’s concentration method or membrane filtration improve the detection rate.
Thus, detection of microfilariae remains the classical confirmatory test and is the expected answer in most examinations.
Explanation of Each Option
A. Clinical features
- Clinical features such as lymphangitis, lymphadenitis, hydrocele, and elephantiasis may suggest filariasis.
- However, these findings are not diagnostic, as they can occur in other conditions.
B. Detection of microfilariae
- Gold standard for classical parasitological diagnosis.
- Performed by demonstrating microfilariae in nocturnal peripheral blood.
- Confirms active infection.
C. Polymerase Chain Reaction (PCR)
- PCR is highly sensitive and specific.
- Mainly used in research settings, epidemiological studies, or specialized laboratories.
- It is not the most commonly used confirmatory test in routine clinical practice.
D. Serological test
- Detection of filarial antigen (e.g., circulating filarial antigen tests) or antibodies is useful, especially in amicrofilaremic infections.
- Antibody tests cannot reliably distinguish past from current infection.
- Although rapid antigen detection tests are widely used in elimination programs, traditional examination questions asking the “most common confirmatory test” generally expect detection of microfilariae.
