Conditions and symptoms
What Is Onchocerciasis (River Blindness)? Plain Guide
Onchocerciasis · say it: ong-koh-ser-KY-uh-sisAlso written: river blindness, Onchocerca volvulus infection, oncho
Short answer
Onchocerciasis, or river blindness, is a parasitic worm infection spread by blackfly bites that affects the skin and eyes.
What it means
Onchocerciasis is caused by a parasitic worm called Onchocerca volvulus. It is spread by the bites of blackflies that breed near fast-flowing rivers, mainly in parts of Africa, with smaller areas in Latin America and Yemen. Adult worms live in lumps under the skin and release huge numbers of tiny larvae, called microfilariae, which move through the skin and eyes. This can cause severe itching, skin changes and, over years, damage to the eyes that can lead to blindness, hence the name river blindness.
It appears on ivermectin and some other antiparasitic labels as a use. These labels warn about the Mazzotti reaction, an inflammatory reaction when many microfilariae die at once, causing itching, rash, fever, joint pain, swollen glands and sometimes dizziness on standing. They also mention eye reactions and extra care in people who also have another worm infection called loiasis (Loa loa).
Onchocerciasis is one of several filarial worm infections. Lymphatic filariasis, which affects the lymph system, is a different one.
Where you may see it
- The 'Indications' and 'Warnings' sections of ivermectin labels
- Mass drug administration programme leaflets
- Skin snip test and travel clinic reports
📄 How it looks on a report
Patients with onchocerciasis may experience Mazzotti-type reactions following treatment.
🙅 What it does not mean
- River blindness is not caused by river water itself; it is spread by blackfly bites near rivers.
- One treatment does not usually kill the adult worms; repeated treatments are often needed.
- A reaction after treatment does not usually mean an allergy to the medicine.
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “Onchocerciasis”
Plain-English explanations of each medicine, from its official FDA label.
- Ivermectin
An antiparasitic medicine, sometimes called a worm-killing medicine (anthelmintic), that the FDA lists as an antiparasitic and pediculicide
🔗 Read more from trusted sources
- “Onchocerciasis” on MedlinePlus ↗
US National Library of Medicine
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