Signs and Symptoms of Filariasis

Signs and Symptoms of Filariasis

Filariasis is actually a very tragic, horrifying and deliberating disease caused by a filaroid nematode parasite named as Wuchereriabancrofti.
This disease is the first discovery of insect transmitted human disease. Generally infection caused by any one filarial nematode known as 'filariasis' though traditionally the term "filariasis" commonly refers to the lymphatic filariasiscaused by Wuchereria or Brugeia sp. Fliaroids are actually tissue dwelling parasites which affects all classes of vertebrates except fish.  

This disease is also known as elephantiasis for the abnormal expansion of the lymph node. Depending upon the area affected by the parasite this disease is classified as i) Lymphatic filariasis ii) Subcutaneous  filariasis iii)Serous cavity filariasis.

The causative agent Wuchereria Bancrofti belongs to the family Onchocercidae.  This parasite shows dimorphism. The adult worms are whitish, translucent, threadlike with smooth cuticle and tapering ends. The female worm(80-100mm long and 0.24-0.30 mm wide) is larger than the male worm (40 mm long and 0.1 mm wide). The life span of adult worm is 10-15 years or more. 

Mosquito acts as an active vector for this disease but accidental transmission of affected blood may also lead to this disease. The period from the entry of the infective third-stage larvae into human host, till the first appearance of microfilariae in circulation is called the biological incubation period of prepatent period which is usually about 8-12 months. 

The period from the entry of the infective larvae till the development of the earliest clinical manifestation is called the clinical manifestation period. The time span of this period is variable but usually 8-16 months though it may often last longer.

Signs and symptoms of Filariasis :

Like other diseases this disease also has some unique symptoms. Some of the usual symptoms are discussed here:
The effects of infection with W. bancrofti display a wide spectrum from clinically silent infections with no apparent inflammation or parasite damage, to mild to intense non granulomatous chronic lymphatic inflammation. 

There are mainly 3 phases:
i) Asymptomatic Phase
ii) Inflammatory or acute phase
 iii) Obstructive phase.

The main sign of this disease is the elephantiasis edema with the thickening of the skin and the tissues situated under it. By this symptom we can assume that the parasite lies in the lymphatic node of the patient. Lower extremities mainly affected by this disease though mucous membrane, amputation stamps get affected less frequently. Different species of filarial worms affect different parts of the body though W. Bancrofti affects legs, vulva, arms, scrotum, and breast while Brugiatimoriaffects the genital area mainly. 

Abdominal pain occurred in this disease as the parasite is a deep tissue dweller. It can be said that elephantiasis is a result of complex immune responses of long duration.The signs and symptoms gradually disappear after the worms die and are absorbed. Repeated super infections over many years are usually required for elephantiasis to occur.

The main two measures in prevention and control of filariasis are
 I) Eradication of vector mosquitoes,
 II) Detection and treatment of carriers. Filariasis is not a life threatening infection though it can cause severe damage to the lymphatic system.

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