Onchoc

erca

AdultsLive in the nodules for approximately 15 years

Female is larger than male

Female worms are capable of producing microfilariae in the subcutaneous nodules for approximately 9 years

MicrofilariaeUnsheathed

Life span: may reach 2 years

Ingested by a blackfly

Occasionally found in peripheral blood, urine, and sputum

Typically found in skin and lymphatics of connect tissues

Onchocerca volvolus

Onchocerca volvolus

Causes Onchocerciasis

“River Blindness” – fertile riverside areas

Blindness in many African Countries

West and Central Africa

Onchocerca volvolus

Yemen and six countries in Latin America

Blindness in many African Countries

Half a million blind people

Manifestation

Pruritus – severe itching pf the skin

Dermatitis – inflammation of the skin

Onchocercomata – adult form fibrous capsules in the subcutaneous nodules

Onchocerca volvolus

Lymphadenopathies – disease in the lymph nodes

Ocular Lesions – could cause blindness

Diagnosis

Skin snips - microfilariae

Corneal-scleral punch (Scalpel and needle)

Sample

Onchocerca volvolus

Incubate for 30mins-2hours in saline or culture medium

Examined for microfilariae that would have migrated from the tissue to the liquid phase of the specimen

Other methodsThose with Ocular Lesions

Slit Lamp Examination (Microfilaria)Substanciapropria of the corneaAnterior chamber

Onchocerca volvolus

Tissue Samples in Nodulectomies (Adult Worms)

Africa : Trunk and Limbs (Simulium Bite Limbs)

America : Head particulary over the scalp (Bite Head Region and Neck)