From Tropical medicine by: Yann A. Meunier, MD

(with contributions from Michael Hole,

Takudzwa Shumba, and B. J. Swanner)

Onchocerciasis (or River Blindness) Treatment
• Ivermectin for microfilariae

• Dosing:
* Ivermectin, 150–200 μg/kg, po, once, for adults and children


Onchocerca volvulus
Geographic Distribution
Onchocerciasis is a filariasis present in 6 countries in Latin America, the
Middle –East (Yemen), and Africa (especially in the Volta basin: Senegal, Guinea,
Sierra Leone, Ivory Coast, Ghana, Benin, Togo, Nigeria, Mali).

According to theWHO in 2013, at least 25 million people are infected with O. volvulus worldwide; including 300,000 who are blind and 800,000 with some visual impairment. Approximately 123 million people are at risk for becoming infected with the parasite. More than 99% of infected people live in sub-Saharan Africa.


Main Symptoms
After a bite by an infected Simulium black fly, the following symptoms appear:
• Cutaneous syndrome
Pruritus, which can be intense (known as craw-craw in Africa), affecting
mainly the lower torso, buttocks, thighs, and pretibial areas. It produces
hyperpigmented plaques and lymphedema (orange skin). Later, hypopigmentation occurs (leopard skin) as well as lichinifi cation (lizard skin). Symptoms
involve more the upper parts of the body in Latin America than in Africa. In
particular, mal morado is found in the elderly with a maculopapular eruption
on the face, neck, arms, and pectoral region accompanied with a mauvish
depigmentation. In Yemen, sowda affects mainly the lower limbs with pruritus
and dark skin. These symptoms evolve faster than in Africa.
• Cystic syndrome
Onchocercomas, which are cystic collections of adult parasites (macrofilariae)
• Ocular syndrome
Its frequency is proportional to the duration and intensity of infection.
Microfilariae can be found in the anterior chamber of the eye. Other symptoms
include keratitis (leading to an onchocercosis pannus), iridocyclitis, chorioretinitis (leading to Hissette-Ridley type of lesions), and post–optic nerve atrophy.
• Other symptoms
Adenopathy (known as “hanging groin” in Africa) and diffuse onchodermatitis.


Treatment
• Ivermectin for microfilariae

• Dosing:
* Ivermectin, 150–200 μg/kg, po, once, for adults and children
• Nodulectomy for macrofilariae