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Onchocerciasis (River Blindness): Treatment & Medication
Updated: Feb 13, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Medical Care
The treatment of onchocerciasis was revolutionized with the introduction of ivermectin in 1987. Ivermectin therapy does not have the adverse reactions of DEC, and it eliminates the need for 6 weekly injections of suramin. The treatment is suitable for both clinical use and mass distribution in endemic areas.11,12,13- Ivermectin is a compound derived from the bacterium Streptomyces avermitilis. The drug causes nematode paralysis by impairing neuromuscular function.
- Ivermectin not only prevents ocular disease but also improves and eliminates the skin disease. A single dose of 150 mcg/kg clears the microfilariae from the skin for several months.
- Ivermectin temporarily decreases the release of microfilariae, but it does not kill adult worms.
- Adverse reactions are similar to the responses of the body to dying microfilariae, but the intensity and rate of development are increased. Adverse effects include fever, edema, pruritus, lymphadenitis, and body pains.
- The frequency and duration of ivermectin therapy still is being debated. As many as 33% of patients in nonendemic areas are cured with only 1 dose of ivermectin, but most patients require additional therapy.14
- Small studies have shown that administration of doxycycline for 6 weeks in addition to ivermectin therapy led to Wolbachia depletion followed by interruption of embryogenesis and reduction in microfilarial loads lasting 18 months.15
- Since ivermectin resistance has been detected in nematode genera other than Onchocerca, strategies targeting eradication of Wolbachia have been undertaken to identify alternative agents for treatment. A study of 5 weeks of doxycycline use without ivermectin showed a reduction in live worms in nodulectomy specimens.16 Additional studies using azithromycin17 or rifampicin18 for Wolbachia eradication have been less efficacious than studies using doxycycline; however, further research may support the use of these agents as alternatives for those intolerant of doxycycline.
- Suramin is used less often than ivermectin and given intravenously.
Surgical Care
Nodulectomy has been a traditional form of therapy in Mexico and Guatemala.
- Moving from village to village, healthcare workers remove nodules from patients, especially nodules in the head.
- This surgical approach may reduce the number of microfilariae that enter the eye, but no strong evidence supports its effectiveness in preventing blindness.
- The removal of nodules may be a valuable adjunct in patients treated with ivermectin.
Medication
Ivermectin is the drug of choice in the treatment of onchocerciasis. The addition of 6 weeks of doxycycline to ivermectin has been shown to be effective in reducing the microfilarial load, which may affect transmission and may prevent or reduce onchocerciasis-related blindness. Suramin may be indicated for use only if ivermectin cannot adequately control the disease. Amocarzine has not been shown to be effective in treating onchocerciasis.19 Both suramin and amocarzine are capable of destroying adult worms. DEC therapy is no longer recommended.
Anthelmintics
Biochemical pathways in parasites are sufficiently different from those in the human host to allow selective interference by using chemotherapeutic agents in relatively small doses.
Ivermectin (Mectizan, Stromectol)
Oral, semisynthetic, broad-spectrum anthelmintic agent isolated from S avermitilis. Binds selectively with glutamate-gated chloride-ion channels in invertebrate nerve and muscle cells, causing cell death. Half-life is 16 h; metabolized in liver. Usual frequency is q12mo for mass treatment programs, but individual therapy may be given in intervals as short as 3 mo.
Adult
15-25 kg: 3 mg PO
26-44 kg: 6 mg PO
45-64 kg: 9 mg PO
65-84 kg: 12 mg PO
>85 kg: 150 mcg/kg PO
Pediatric
<15 kg: Not established
>15 kg: Administer as in adults
May interact with other ligand-gated chloride channels (eg, GABA-gated channels)
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Patients with sowda may be more likely to have severe adverse reactions, especially edema and aggravation of onchodermatitis; treat women who intend to breastfeed only when risk of delayed treatment outweighs possible risks to the newborn caused by excretion in milk; adverse reactions include arthralgia and/or synovitis, lymph node enlargement and tenderness, pruritus, edema, fever, and papular, pustular, and frank urticarial rash
Suramin (Metaret)
Polyanionic compound developed as an antiparasitic drug for treatment of CNS trypanosomiasis. IV antiparasitic agent effective against African trypanosomiasis and onchocerciasis. Most often, a 10% solution is used. Administration of a test dose of 100-200 mg is advised before initiating treatment.
Adult
66.7 mg/kg total dose slow IV injection divided in 6 weekly increments
Pediatric
<10 years: Not recommended
>10 years: Administer as in adults
None reported
Documented hypersensitivity; severe liver or renal disease; blindness; mild-to-moderate infections
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Immediate adverse effects include nausea, vomiting, shock, and loss of consciousness; skin reactions and abdominal pain may occur; delayed effects include paresthesia, skin eruptions, fever, elevated LFTs results, photophobia, albuminuria, hematuria, and occasional adrenal insufficiency; monitor CBC; perform coagulation tests; evaluate for neuropathy during therapy
Antibiotics
When used concurrently with ivermectin therapy, tetracycline antibiotic therapy (eg, with doxycycline) depletes Wolbachia endosymbionts and may decrease transmission and reduce or prevent onchocerciasis-related blindness secondary to disruption of female nematode embryogenesis.20,21
Doxycycline (Doryx, Vibramycin)
Broad-spectrum, synthetically derived bacteriostatic antibiotic in tetracycline class. Almost completely absorbed, concentrates in bile, and is excreted in urine and feces as a biologically active metabolite in high concentrations.
Inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. May block dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
Adult
100 mg PO qd/bid for 6 wk in conjunction with ivermectin therapy
Pediatric
Not established
Bioavailability decreases with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; tetracyclines can increase hypoprothrombinemic effects of anticoagulants; tetracyclines can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy
Documented hypersensitivity; severe hepatic dysfunction
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last one-half of pregnancy through age 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines
More on Onchocerciasis (River Blindness) |
| Overview: Onchocerciasis (River Blindness) |
| Differential Diagnoses & Workup: Onchocerciasis (River Blindness) |
 Treatment & Medication: Onchocerciasis (River Blindness) |
| Follow-up: Onchocerciasis (River Blindness) |
| Multimedia: Onchocerciasis (River Blindness) |
| References |
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References
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Further Reading
Keywords
onchocerciasis, river blindness, African river blindness, blinding filariasis, Robles disease, craw-craw, Onchocerca volvulus, O volvulus, Simulium species, Simulium damnosum, Simulium neavei, Simulium metallicum, Simulium ochraceum, Simulium exiguum, black fly, microfilariae, onchocercal dermatitis, hanging groin, leopard skin, sowda, onchocercal dermatitis, acute papular onchodermatitis, APOD, chronic papular onchodermatitis, CPOD, lichenified onchodermatitis, LOD,
