Diseases Caused by Helminths > Filariasis (Elephantiasis)

Filariasis is a parasitic disease caused by filarial nematode worms. The advanced condition in which affected body parts become grossly enlarged due to chronic lymphatic obstruction is called elephantiasis.

Causative Organisms:

• Wuchereria bancrofti - the primary causative filarial worm
• Brugia malayi (also written as W. malayi in some references) - another causative species
• Both are nematodes (roundworms) and are classified as helminths

Vector:

• Transmitted through the bite of female Culex mosquitoes carrying infective larvae
• The mosquito ingests microscopic larvae (microfilariae) from an infected person's blood, which then develop further inside the mosquito before becoming infective

Habitat of Adult Worms:

• Adult worms live inside the lymphatic vessels and lymph nodes of the human body
• They commonly affect the lymphatics of the lower limbs and genital organs

Pathogenesis:

• Adult worms cause chronic inflammation of lymphatic vessels and lymph nodes
• This leads to obstruction of lymph flow
• Lymph accumulates in tissues, resulting in lymphedema and progressive swelling
• Prolonged obstruction causes gross enlargement of affected parts - elephantiasis

Signs and Symptoms:

Treatment:

• Diethylcarbamazine (DEC) - drug of choice; taken as a course
• Supporting treatment includes anti-inflammatory drugs, antiallergics, antibiotics, and diuretics
• Very large swellings may require surgical management

Prevention and Control:

• Avoid mosquito bites - use mosquito nets, screens, and repellents
• Eradicate mosquito breeding by eliminating stagnant water
• Community-level vector control programs reduce transmission

Wuchereria bancrofti: life cycle