Lymphatic filariasis is the most common cause of secondary lymph edema worldwide.

     Three helminthes are responsible. They are Wuchereria bancrofti, Brugia malayi, and Brugia timori.

     Man is the definitive host for these worms. The adult worms live in lymphatics and produce approximately 50,000 microfilarias per day. Mosquitoes serve the intermediate vector and spread the disease from one primary host to the other.

     Mosquitoes, which feed from an infected human being, ingest microfilaria. They undergo exsheathing in its stomach. The first stare larva pierces muscles and migrate to thoracic muscles. In thoracic musculature they undergo two moultings to become the third stage larva, which reaches the proboscis to be inoculated to the next victim. There is no amplification of the organism in the mosquito. Once, after entering the definitive host they migrate to lymphatics and mature there.

     The incubation period for filariasis is 8 to 16 months. Clinical features depend on the stage of the disease. In acute stage they include fever with chills, lymphangitis, lymphadenitis, and Lympoedema (grade 1). Microfilaria can be detected in the peripheral smear. At this stage depending on the diurnal variations, wet film preparation will help to demonstrate motile larva. Chronic stage follows 10 to 15 years after acute episode. In chronic stage manifestation are due to obstruction of protein rich lymph and resulting fibrosis leading to irreversible non-pitting brawny edema, fissuring of skin and hyper plastic changes occur. Super infection of these poorly vascularised tissues is common.

     Usual areas involved include limbs, female breast, scrotum and labia. Massive enlargement of these organs is referred to as elephantiasis. Obstruction of retroperitonial lymphatics leads to increased renal lymphatic pressure that leads to rupture of the renal lymphatics and resulting in chyluria.

     Diagnosis is demonstration of microfilaria in the blood by a peripheral smear examination. ELISA or rapid format immunochromatographic card test can detect Wuchererial antigens. Worms can be detected in lymphatics or scrotum and breast in affected person with 80% sensitivity. PCR to detect worm DNA been developed. Early lymphatic abnormalities can be demonstrated by radionucliede lymphoscintigraphy imaging at the limbs.

    Treatment is by DEC 6mg/kg per day as three divided doses for 12 days. Ivermectin 200 micro gm per kg single dose is effective. Albendazole 400mg twice daily for 21 days is also used. Single dose of Ivermectin along with albendazole or DEC with albendazole is also found effective.

     Filariasis is a health problem of huge magnitude with 133 million affected worldwide and 1 million newly affected every year. It is not a fatal condition, but the morbidity it causes is serious. The eradications deemed possible as of the following facts:

Biological facts.

a.      Man is the only definitive host for W.bancrofti and B.malayi, which are responsible for 98% of cases.

b.     There is no amplification of the organisms inside the vector.

c.     Prolonged exposure is necessary for the spread of the disease.

Technical factors:

Effective diagnosis and treatment provisions are available. Asymptomatic filariasis is the presence of microfilaria in the blood without its clinical manifestations. It is treated with DEC as this may progress to the disease stage.

Tropical pulmonary eosinophilia is one condition due to sequestration of worms in lungs. Clinical features include mild fever, nocturnal cough, wheezing and breathlessness. Chest X-ray shows increased broncho vascular markings and diffuse miliary lesions. Eosinophilia is found differential count. Treatment is by DEC 6mg/kg per day for 12 days. Relapse need re treatment.

Seminar was conducted on January 27^th for CRRI.

Seminar presented by -Dr.NIZAMUDHEEN.,  Dr.R.NIRANJANA.