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Disease Profile

Onchocerciasis

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
<1 / 1 000 000

< 331

US Estimated

< 514

Europe Estimated

Age of onset

All ages

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ICD-10

B73

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

River blindness; Robles' disease

Summary

Onchocerciasis is a rare tropical parasitic disease transmitted by a black fly. Infection by the parasite can cause eye and skin problems. In humans, the parasitic worms live under the skin (subcutaneous nodules) and produce larvae (microfilariae). The larvae are found throughout the body, but especially in the skin and eyes.[1] Repeated bites by infected flies increase the number of adult worms and larvae. Chronic skin onchocerciasis (onchodermatitis) causes itching, a rash with small pimples (papular rash), scarring, and thickened, leathery skin (lichenification). Other symptoms may develop over time and might include saggy skin (such as ''hanging groin''), patchy areas of much lighter colored skin (leopard skin), ichthyosis-like lesions (''lizard skin''), darkening of the skin, and very severe itching. The eye infection is known as river blindness because the blackfly carrying the parasite lives near fast-flowing waters. Symptoms of an eye infection may include itchy eyes, red eyes, and sensitivity to light (photophobia). In some cases, the larvae may infect the optic nerve. As the common name suggests, infection of the eye by onchocerciasis can lead to vision loss and eventually blindness.[2][3]

The disease is caused by the parasitic worm Onchocerca volvulus and is transmitted by the bite of an infected black fly. About 90% of the cases occur in Africa. Treatment aims to remove the larvae (microfilariae), to improve symptoms, to prevent progression of eye lesions, and to stop the parasite from being passed back to black flies so other people do not become infected. Medications include an anti-parasitic known as ivermectin, antibiotics such as rifampinazithromycin, and doxycycline, and, another recently approved anti-parasitic drug, Moxidectin.[3]

Treatment

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.
  • The United States Agency for International Development (USAID) launched the Neglected Tropical Diseases Initiative in 2006, the first global effort to support country programs to integrate and scale up delivery of preventive medication for five neglected tropical diseases: lymphatic filariasis, schistosomiasis, trachoma, onchocerciasis, and soil-transmitted helminthiasis. Click on the link to view information on this condition.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Onchocerciasis. Click on the link to view a sample search on this topic.

References

  1. Onchocerciasis (river blindness) disease information. World Health Organization (WHO). https://www.who.int/blindness/partnerships/onchocerciasis_disease_information/en/. Accessed 6/26/2018.
  2. Parasites Onchocerciasis (also known as River Blindness). Centers for Disease Control and Prevention (CDC). August 10, 2015; https://www.cdc.gov/parasites/onchocerciasis/.
  3. Smith DS. Onchocerciasis (River Blindness). MedScape Reference. June 22, 2018; https://emedicine.medscape.com/article/224309-overview.