Onchocerciasis (River Blindness) Treatment & Management

Updated: Jun 22, 2018
  • Author: Darvin Scott Smith, MD, MSc, DTM&H; Chief Editor: Mark R Wallace, MD, FACP, FIDSA  more...
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Treatment

Medical Care

Because most of the pathogenesis of onchocerciasis is secondary to microfilariae, the goal of therapy is to eliminate the microfilarial stage of disease to improve symptoms, to prevent progression of eye lesions, and to interrupt disease transmission.

Ivermectin is considered to be the drug of choice as a microfilaricidal agent. [41, 42] Repeated dosing at intervals of 3–12 months is recommended for at least 10-12 years. More frequent dosing is reserved for patients who experience frequent symptomatic recurrences.

Ivermectin is usually well-tolerated. Dying microfilaria may result in pruritus and adenopathy (Mazzotti reaction), leading to angioedema in rare cases. Ocular inflammation may also be triggered by dying microfilariae. To minimize this in individuals with microfilariae observed during slit-lamp examination, some experts recommend using a short course of prednisone (2-3 d) along with ivermectin. More frequent dosing with ivermectin (every 3 mo instead of every 12 mo) may reduce inflammatory complications because it does not permit microfilarial numbers to build, thus reducing the number of dead organisms after treatment.

Concomitant infection with Loa loa should be ruled out, as ivermectin may precipitate toxic encephalopathy in these patients.

Ivermectin has little effect on adult worms. It reduces the burden of microfilaria and the risk of complications but does not cure the disease. Ivermectin may have a modest effect on infection rates with selected intestinal helminths, such as Strongyloides and Ascaris, although it is not effective against hookworm. [43]

Targeting endosymbiotic Wolbachia species has emerged as an exciting new approach in the control of onchocerciasis. Studies of doxycycline therapy (100–200 mg/d for 6 wk) have shown great promise. [6, 7, 44, 45] Doxycycline interrupts microfilarial embryogenesis, dramatically decreasing or eliminating microfilaria for at least 18 months after treatment. The drug has modest activity against adult worms, reducing numbers by approximately 50%-60%. The combination of doxycycline and ivermectin given together is more effective than either drug alone. [46] However, doxycycline has side effects and must be given daily, which limits its usefulness for large scale treatment programs. [47] . It has been suggested that minocycline may be more efficient than doxycycline in the elimination of Wolbachia. [48]

Moxidectin is an antiparasitic drug that was approved by the FDA in June 2018 to treat onchocerciasis in patients aged 12 years or older. The WHO initiated clinical trials for use in onchocerciasis treatment in 2009. [49] Moxidectin is closely related to ivermectin but yields a more sustained reduction in microfilarial levels. FDA approval was based on a double-blind, parallel group, superiority trial (n=1472) that compared moxidectin (8 mg PO once) with ivermectin (150 mcg/kg PO once). The trial took place in Ghana, Liberia, and the Democratic Republic of the Congo. Results showed skin microfilarial loads (ie, parasite transmission reservoir) were lower from month 1 to month 18 after moxidectin treatment than after ivermectin treatment, with an 86% difference at month 12. Moxidectin would therefore be expected to reduce parasite transmission between treatment rounds more than ivermectin could, thus accelerating progress toward elimination. [50]

Investigators have also studied rifampin and azithromycin, but early results appear to be inferior to those of doxycycline. [51, 52, 53]

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Surgical Care

Nodulectomy can result in cure only if excision eliminates all adult worms. Thus, this is not a practical choice in patients with multiple nodules or in patients in whom nodules are not clinically evident. [39]

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Consultations

See the list below:

  • Infectious disease specialist

  • Ophthalmologist

  • Dermatologist

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