Onchocerciasis results from infestation by the nematode Onchocerca volvulus and is characterized by troublesome
itching, skin lesions, and
eye manifestations. Although partially controlled by international mass prevention programs,
onchocerciasis remains a major health hazard and is endemic in Africa, Arabia, and the Americas.
Onchocerciasis is spread by
bites from infested black flies, which transmit larvae that subsequently develop into adult filariae. Skin symptoms are commonly nonspecific and include severe
pruritus, acute and chronic
dermatitis,
vitiligo-like
hypopigmentation, and
atrophy. Onchocercal ocular disease covers a large spectrum of manifestations, which in severe cases, may lead to
blindness. Diagnosis is usually made by direct visualization of the larvae emerging from superficial skin biopsies, "skin snips." In some cases, the microfilariae can also be directly observed at the
slit lamp when migrating into the anterior chamber of the eye.
Ivermectin is, at present, the
drug of choice for skin and ocular manifestations. Recent research using a chemotherapeutic approach that targets filarial Wolbachia symbionts in the treatment and control of
onchocerciasis, however, suggests that 100 mg/d of
doxycycline for 6 weeks might be effective in reducing the filarial load and preventing ocular symptoms.