Filariasis (Elephantiasis); clinical features, treatment and prevention

Introduction

This is a parasitic and debilitating disease caused by the filarial worm. It is caused by 3 distinct species of filarial worms namely Wuchereria bancrofti, Brugiamalayi and Brugiatimori.

It affects the legs, scrotum and the breasts. Transmission occurs through the bite of mosquitoes (vetor) species, aedes, culex, anopheles & mansonia.

The W.Buncrofti is strictly a human pathogen and it is distributed in tropical areas worldwide whereas B.malayi & B.timori infects a number of wild and domestic animals.

Life Cycle

Photo from Wikipedia

Filariform larvae enters the human body during a mosquito bite and migrate to the nearest lymph gland where they mature into the thread like adult worms about 3 months to 1 year later. The adult produces sheathed microfilariae that migrate into lymph and blood channels. Mosquitoes pick up the microfilaria when they bite or feed on man. In the lymphatic channels, the worm dies and produces fibro-proliferative granuloma which obstruct the lymph channels causing lymphoedoma & elephantiasis. Once the microfilariae enters the mosquito through blood meal, they penetrate the insect’s midgut and move to the thoracic muscle where they mature into infective Iarvae.

Signs and Symptoms

• Acute lymphangitis with fever & chills.
• Arthritis; knee and ankle joints warm, tender and painful.
• Chyluria: leaks of lymphatic fluid into the kidneys and turns the urine milky white.
• Lymphadenitis; swollen lymph nodes.
• Lymphoedena

Treatment

• Ivermectin (this drug should not be given to pregnant woman and children less than 4years), Albendazole, DEC (diethylcarbamazine) are good micro filaricides.
• Surgery to open up the lymph flow.
• Antibiotics for bacterial infections.
• Elevation of the limb and the use of elastic pressure bandages.

Diagnosis

• Blood sample collected at night and examined under microscope.
• Clinical features.

Prevention of Filariasis

• Avoid mosquito bite by;
• Using mosquito net at night.
• Wearing protective clothing like long sleeve shirts and long trousers at night.
• Using mosquito repellent at night.

• Prevent the breading of mosquito larvae by;
• Always keeping the environment clean.
• Draining all standing waters or pouring oil over stagnant waters.
• Spraying the breeding sites with chemicals.
• Providing proper refuse disposal methods.

• People in endemic area like Africa should take chemoprophylaxis e.g. S.P.
• Prompt treatment of all infected persons.
• Annual mass treatment with ivermectin.
  

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