Onchocerciasis (river blindness)

Pathogen & epidemiology

  • Onchocerca volvulus

Life-cycle

  • Black fly (genus Simulium) takes a blood meal and larvae enter wound

  • Adults in s/c tissues, produce microfilariae typically found in skin and lymphatics of connective tissue (occasionally in blood, urine, sputum)

  • Blackfly takes a blood meal and ingests mf

Clinical

Triad

  • Skin nodules (adult worms)

  • Dermatitis: Skin itch (leopard skin)

  • Eyes: 5% blind


  • Association with Nodding syndrome

Diagnosis

  • Skin snip

  • Clinical, Eosinophilia, eye (slit lamp)

  • Mazzotti DEC test

Treatment

  • Doxycycline for 4-6 weeks (wolbachia)

  • Ivermectin every 3-6 months (not if Loa Loa)

Prevention

  • MDT

  • Disease control