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Onchocerciasis

Onchocerciasis, commonly called river blindness, is a parasitic infection caused by the roundworm Onchocerca volvulus. Blackflies breeding near fast-flowing rivers carry the larvae and pass them to humans through bites. While most cases occur in sub-Saharan Africa, the disease is also endemic in parts of Yemen and Latin America, and it remains a health concern for travellers and aid workers working near affected river systems.

Stromectol

Ivermectin

3 · 6 · 12mg

Ivermectin 3mg, 6mg and 12mg tablets, used for strongyloidiasis, scabies and onchocerciasis. It binds chloride channels found only in invertebrates.

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Key points

  • Larvae carried by riverside blackflies enter the body through bites and mature into worms that settle under the skin.
  • These adult worms produce microfilariae that spread through the skin, triggering intense itching and eventually a thickened, patchy skin appearance.
  • Eye involvement occurs when migrating microfilariae die within ocular tissue, and the ensuing inflammation slowly destroys the cornea, leading to blindness.
  • One oral dose of ivermectin rapidly eliminates the microfilariae, but repeat treatment every few months is needed since adult worms survive.

What the infection does to skin and eyes

The worms mature under the skin, forming nodules and producing millions of microscopic offspring called microfilariae. These migrate through the skin, causing intense itching, rashes, and over time a thickened or depigmented appearance sometimes called “leopard skin”. When microfilariae reach the eyes and die there, the resulting inflammation gradually damages the cornea and can lead to permanent vision loss, which is how the disease earned its common name.

Treating onchocerciasis

The standard approach is a single oral dose of ivermectin, an antiparasitic that rapidly kills the microfilariae and suppresses new production for several months. Repeat doses at six- to twelve-month intervals are typically needed because ivermectin does not kill adult worms. It belongs to the broader class of antiparasitic medicines used against a range of worm and parasite infections. Anyone with possible eye involvement or a heavy worm burden should be assessed by a clinician before treatment.

Further reading