Lymphatic Filariasis

Posted by e-Medical PPT
Disease manifestation range from
Acute-Filarial fever
Chronic-Lymphangitis, Lymphadenitis, Elephantiasis of genitals/legs/arms
Tropical Pulmonary Eosinophilia (TPE)
Filarial arthritis
Epididimoorchitis
Chyluria, etc.

Lymphatic Filariasis Diagnostic Methods
Lymphatic Filariasis can be diagnosed clinically and through laboratory techniques.

Clinically, diagnosis can be made on circumstantial evidence with support from antibody or other laboratory assays as most of the LF patients are amicrofilaraemic and in the absence of serological tests which is not specific other than CFA (ICT). In TPE, serum antibodies like IgG & IgE will be extremely high and the presence of IgG4 antibodies indicate active infection.

1. Demonstration of microfilarae in the peripheral blood
a. Thick blood smear: 2-3 drops of free flowing blood by finger prick method, stained with JSB-II
b. Membrane filtration method: 1-2 ml intravenous blood filtered through 3┬Ám pore size membrane filter
c. DEC provocative test (2mg/Kg): After consuming DEC, mf enters into the peripheral blood in day time within 30 - 45 minutes.
2. Immuno Chromatographic Test (ICT): Antigen detection assay can be done by Card test and through ELISA. Circulating Filarial Antigen detection is regarded as “Gold Standard” for diagnosing Wuchereria bancrofti infection. Specificity is near complete, sensitivity is greater than all other parasite detection assays, will detect antigen in amicrofilaraemic as well as with clinical manifestations like lymphoedema, elephantiasis.
3. Quantitative Blood Count (QBC):
QBC will identify the microfilariae and will help in studying the morphology. Though quick it is not sensitive than blood smear examination.
4. Ultrasonography:
Ultrasonography using a 7.5 MHz or 10 MHz probe can locate and visualize the movements of living adult worms of W.b. in the scrotal lymphatics of asymptomatic males with microfilaraemia. The constant thrashing movements described as “Filaria dance sign” can be visualized.
5. Lymphoscintigraphy:
The structure and function of the lymphatics of the involved limbs can be assessed by lymphoscintigraphy after injecting radio-labelled albumin or dextran in the web space of the toes. The structural changes can be imaged using a Gamma camera. Lymphatic dilation & obstruction can be directly demonstrated even in early clinically asymptomatic stage of the disease.
6. X-ray Diagnosis:
X-ray are helpful in the diagnosis of Tropical pulmonary eosinophilia.
Picture will show interstial thickening, diffused nodular mottling.
7. Haematology : Increase in eosinophil count

Clinical Manifestations
Manifestations are 2 types
Lymphatic Filariasis (Presence of Adult worms)
Occult Filariasis (Immuno hyper responsiveness)..

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