Question

Life cycle and pathogenicity of wuchereria bancrofti

Answer 1

The pathogenic effects in the human being are caused by mainly the adults of Wuchereria bancrofti.The disease is commonly called Wuchereriasis,Bancroft’s Filariasis or Classical Filariasis. The disease is generally asymptomatic showing no external signs of infection. However, these cause the damage to the lymphatic system, kidneys and the immune system of the body. In case the infection is severe, the host shows various pathological symptoms. The microfilariae though circulate in the blood are not known to cause any pathogenic effects, except in severe cases. The disease caused by microfilariae is known as Occult Filariasis.

The various pathogenic effects caused by filarial worm are as follows.

a)  Lymphangitis

Presence of adult worms present in the lymphatics results in the inflammation of the lymphatic system, called lymphangitis. The inflammation may be caused by the following.

The movement of adult worms in the lymphatic system  causes mechanical irritation.The growing larvae release certain metabolites which cause reaction in the body.The fertilized females secrete toxic fluids during birth of microfilariae resulting in inflammatory reactions.The dead worms in the lymphatic system disintegrate resulting in some toxic products.The lymphatic system gets secondary bacterial infections.  

The inflammed areas are extremely painful and appear as cord-like swellings.