Onchocerciasis: Causes, Spread, Impact and Global Efforts to Eliminate It

The parasitic worm Onchocerca volvulus is the cause of the neglected tropical illness onchocerciasis, also referred to as river blindness. In some parts of Africa and Latin America, it is still a serious public health concern, especially for people that live close to swift-moving rivers where the disease’s vector, blackflies, grow in abundance. Millions of people are still afflicted by the virus, which causes long-term disability, poverty, and social marginalisation despite advancements made worldwide.

What Causes Onchocerciasis?

The bite of an infected blackfly (genus Simulium) can spread onchocerciasis. Microfilariae, which are tiny larvae, enter the human body when the fly bites.

These larvae migrate to the eyes after causing intense itching, swelling, and rashes as they pass through the skin. Repeated exposure over time causes inflammation and optic nerve damage, which can lead to permanent blindness or visual impairment.

Symptoms and Health Impact

Skin, eyes, and general quality of life are all impacted by the condition.

• Among the main symptoms are:
• Severe skin inflammation and itching
• The term “leopard skin” refers to skin depigmentation.
• Adult worm-containing nodules beneath the skin
• Progressive vision loss that, in extreme circumstances, results in blindness

In addition to causing personal pain, the illness lowers economic output and agricultural productivity since afflicted individuals frequently are unable to work or attend school.

Geographical Distribution

Over 95% of cases of onchocerciasis are found in sub-Saharan Africa.

There are smaller pockets in:

• Yemen
• Venezuela and Brazil (historically, currently on the verge of disappearance)

Because of the ideal conditions for blackfly breeding, communities near rivers and forests are most vulnerable.

Prevention and Global Control Efforts

Ivermectin administered once or twice a year by the Mass Drug Administration (MDA) is the most successful intervention.

Important tactics consist of:

• Ivermectin distribution throughout the community to lower the parasite load
• Vector control, such applying larvicides to lower the number of blackflies
• Community awareness and health education
• Monitoring progress and tracking reinfection through surveillance

The disease burden has been considerably decreased by international initiatives like the Onchocerciasis Elimination Program for the Americas (OEPA) and the African Programme for Onchocerciasis Control (APOC).

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