November 2024 Newsletter: Onchocerciasis

What Is Onchocerciasis? Understanding the Disease Behind “River Blindness”

In many parts of Africa and some regions in Latin America and Yemen, blackflies carry a parasite that causes more than just an itchy bite. It causes onchocerciasis, also known as river blindness. This tropical disease affects millions, despite being largely unheard of, leading to chronic skin conditions, intense discomfort, and in severe cases, permanent vision loss. Despite being preventable, river blindness remains one of the leading causes of blindness worldwide, particularly in communities with limited access to healthcare and clean water.

What Is Onchocerciasis?

Onchocerciasis is a parasitic disease caused by a worm called Onchocerca volvulus. It is transmitted to humans through the bite of an infected blackfly, which breeds near fast-flowing rivers and streams, hence the name “river blindness.” Once inside the human body, the worms produce microscopic larvae (called microfilariae) that migrate through the skin and eyes, triggering intense itching, skin damage, and, in severe cases, permanent blindness.

How Common Is It?

• More than 20 million people are infected worldwide.

• Over 99% of cases occur in sub-Saharan Africa.

• Around 1.15 million people live with vision loss due to onchocerciasis.

• Approximately 200 million people are at risk in endemic areas.

  
  

What Are the Symptoms?

Onchocerciasis affects both the skin and the eyes:

Eye Symptoms Include:

• Redness, eye pain, and light sensitivity

• Progressive damage to the cornea and retina

• Partial or total vision loss

• Blindness can occur over time without treatment

  
  

Skin Symptoms Include:

• Extreme itching (often called “leopard skin”)

• Skin thickening and discoloration

• Nodules under the skin where adult worms live

• Social stigma due to visible skin damage

Is There a Cure?

There is no cure, but the disease can be controlled and blindness can be prevented with regular treatment using:

• Ivermectin (Mectizan®): A medicine that kills microfilariae and helps prevent new infections. It's donated and distributed annually in affected communities through mass drug administration (MDA) programs.

• Doxycycline: Targets adult worms but is used in more limited settings.

  
  

Hope Through Prevention

Thanks to global public health efforts, onchocerciasis has been eliminated as a public health problem in some countries, including parts of Latin America and Uganda. The World Health Organization continues to work toward elimination in all endemic regions.

Simple strategies help stop transmission:

• Annual community-wide distribution of ivermectin

• Vector control (reducing blackfly populations)

• Public education and screening

  
  

Why It Matters

Onchocerciasis isn’t just a health issue, but rather a human rights and social justice issue. It impacts people's ability to work, care for their families, and live with dignity. Ending river blindness would not only mean restored vision, but also restored opportunity, and stronger communities. While onchocerciasis is virtually unknown in many parts of the world, it continues to affect millions of people living in poverty. But it's important to realize that it is preventable and eliminable with continued support, awareness, and action.