• Also known as "river blindness"
  • Second most common cause of infectious blindness worldwide (~300,000 people worldwide - another ~800,000 have visual disturbances)
    • Second only to Trachoma
    • 99% of infected individuals live in Africa
  • Caused by Onchocerca volvulus
    • A round worm (Nematode)
  • Spread by the black fly (genus Simulium)
    • Bite during the day time
    • Live in and near fast flowing streams and rivers

Clinical Features

Sclerosing keratitis from onchocerciasis.
Palpable onchocercal nodule.
Onchocercal skin disease.
Leopard skin.
  • Mainly consist of cutaneous and ocular symptoms secondary to the inflammation reactions from migration of the larvae or death of the larvae

Cutaneous manifestations

  • Pruritis
  • Onchodermatitis - pruritic cutaneous nodules (may be acute or chronic)
  • Elephant skin - skin thickening
  • Lizard skin - skin atrophy and wrinkling
  • Leopard skin - areas of depigmentation

Ocular manifestations

  • Localized punctate keratitis that can become sclerosing keratitis → opacification of the cornea
    • Thought to be caused by migration of the microfilariae to the corneal surface
    • Some evidence exists to suggest that the ocular manifestations are from the immune response to Wolbachia (an endosymbiant to Onchocera)

Differential Diagnosis

Travel-related skin conditions

See also domestic U.S. ectoparasites


  • Skin snip
    • Multiple small (1-2 gm) snips are placed in normal saline and presence of microfilariae detected
    • Can PCR biopsy if negative for microfilariae
  • Mazotti test
    • Place diethylcarbazine (DEC) on patch of skin - localized pruritus and urticaria are positive reactions


  • Ivermectin
    • 150mcg/kg one time dose
    • Usually distributed in endemic areas as part of a mass drug administration (2 doses 6 months apart, every three years)


  • Discharge

See Also

External Links