Onchocerciasis - Onchocerca volvulus Life Cycle

1) Blackfly (genus Simulium) takes a blood meal (L3 larvae enter bite wound)

Human Stages:

2) Subcutaneous tissues

3) Adults in subcutaneous nodule

4) Adults produce unsheathed microfilariae that typically are found in skin and in lymphatics of connective tissues, but also occasionally in peripheral blood, urine, and sputum.

Blackfly Stages:

5) Blackfly takes a blood meal (ingests microfilariae)

6) Microfilariae penetrate blackfly's midgut and migrate to thoracic muscles 

7) L1 larvae

8) L3 larvae

9) Migrate to head and blackfly's proboscis



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