Onchocerca volvulus is a helminth.
Disease / Pathology
Onchocerca volvulus is transmitted by the black fly (simulium) and has no periodicity.
Location in the Host
Onchocerca volvulus adults are located in subcutaneous nodules while the microfilariae are found in skin and in lymphatics of connective tissue.
Onchocerca volvulus is found in South & Central America, and Africa.
Onchocerca volvulus has the life cycle depicted below. The L3 stage of the larvae are the infective stage transmitted to the human host. The microfilariae ingested by the blackfly undergoes undoes three molts to become the L3 larvae stage that migrates to the head of the blackfly and is found in the blackfly’s proboscis.
Morphology & Diagnosis
Onchocerca volvulus microfilariae are approximately 148-355 um in length. Nuclei do not extend to the tip of the tail which is tapered.