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Onchocerciasis in a Teenager From Africa—Diagnosis

Onchocerciasis in a Teenager From Africa—Diagnosis Diagnosis: Onchocerciasis (river blindness). Microscopic findings The excisional biopsy specimen of the subcutaneous nodule demonstrated granulomatous inflammation with numerous filariae that had thick cuticles with annulations (eccentric ringlike projections) and contained abundant microfilariae. The skin overlying the nodule displayed dermal microfilariae with lymphoeosinophilic infiltration. Discussion Onchocerciasis, caused by the filarial nematode Onchocerca volvulus, is the second leading infectious cause of blindness worldwide. Nearly all of the world's estimated 18 million infected persons live in sub-Saharan Africa.1,2 Onchocerciasis is easily misdiagnosed owing to its long incubation period and its unfamiliarity to physicians working in nonendemic areas. Clinical manifestations of onchocerciasis are found in the skin (eg, dermatitis, subcutaneous nodules, and lymphadenitis) and in the anterior and posterior chambers of the eyes (eg, keratitis and chorioretinitis). Skin findings include acute and chronic papular dermatitis, lichenified dermatitis, atrophy, depigmentation, onchocercomata (subcutaneous nodules), and inguinal lymphadenopathy.3,4 Eye findings occur exclusively among persons from endemic areas. Adult O volvulus organisms do not migrate through the eye, but motile microfilariae may be seen on slitlamp examination of the anterior chamber. In long-standing infection, sclerosing keratitis, neovascularization, and blindness may ensue.5 Like all nematodes, O volvulus has a 5-stage life cycle. Humans are the only definitive host. Worldwide disease distribution parallels the niche of Simulium black flies, which breed near fast-flowing streams. Infective larvae are inoculated subcutaneously with black fly bites; larvae mature to adult nematodes and may live 10 years within encapsulated subcutaneous or deep tissue nodules. The diagnosis of onchocerciasis is usually made by removing a small amount of dermis for direct demonstration of microfilariae (skin snip). Multiple skin snips should be obtained from affected areas (eg, scapulae, iliac crests, and lateral calf muscles) and held in saline-filled microplate wells at 37°C. Low-power microscopy reveals dermal microfilariae. Alternatively, as in this patient, excised subcutaneous nodules will demonstrate adult worms. Serologic analysis may be helpful in diagnosing expatriates (who often have negative skin snips) or in following treatment response. Polymerase chain reaction amplification of skin snips is a sensitive and specific diagnostic method for diagnosing lightly infected patients. Eosinophilia may suggest the diagnosis, but may be absent or attributable to other causes. The treatment of choice is ivermectin, which does not kill adult worms; treatment may therefore be needed for prolonged periods. Fever, pruritus, urticaria, edema, and postural hypotension may occur in persons with severe microfilaremia, but such symptoms are usually self-limited. Article Submissions Clinicians, local and regional societies, and residents and fellows in dermatology are invited to submit quiz cases to this section. Cases should follow the established pattern and be submitted double-spaced. Photomicrographs and illustrations must be clear and submitted as 3 positive color transparencies and as 3 color prints. Material should be accompanied by the required copyright transfer statement, as noted in "Instructions for Authors." Material for this section should be submitted to Michael E. Ming, MD, Department of Dermatology, University of Pennsylvania Health System, 2 Maloney Bldg, 3600 Spruce St, Philadelphia, PA 19104-4283. Reprints are not available from the authors. References 1. World Health Organization, WHO fact sheets: onchocerciasis (river blindness) Available at:http://www.who.int/health-topics/oncho.htmAccessed June 9, 2004 2. Freedman D Onchocerciasis Guerrant RLedWalker DHedWeller PFed Tropical Infectious Diseases. New York, NY Churchill Livingstone Inc1999;873- 886Google Scholar 3. McCarthy JSOttesen EANutman TB Onchocerciasis in endemic and nonendemic populations: differences in clinical presentation and immunologic findings J Infect Dis. 1994;170736- 741PubMedGoogle ScholarCrossref 4. Wortman PD Protozoan and helminth infections Harahap Med Diagnosis and Treatment of Skin Infections. Malden, Mass Blackwell Publishers1997;286- 290Google Scholar 5. Hall LRPearlman E Pathogenesis of onchocercal keratitis (river blindness) Clin Microbiol Rev. 1999;12445- 453PubMedGoogle Scholar http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Dermatology American Medical Association

Onchocerciasis in a Teenager From Africa—Diagnosis

Archives of Dermatology , Volume 140 (9) – Sep 1, 2004

Onchocerciasis in a Teenager From Africa—Diagnosis

Abstract

Diagnosis: Onchocerciasis (river blindness). Microscopic findings The excisional biopsy specimen of the subcutaneous nodule demonstrated granulomatous inflammation with numerous filariae that had thick cuticles with annulations (eccentric ringlike projections) and contained abundant microfilariae. The skin overlying the nodule displayed dermal microfilariae with lymphoeosinophilic infiltration. Discussion Onchocerciasis, caused by the filarial nematode Onchocerca volvulus, is the second...
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Publisher
American Medical Association
Copyright
Copyright © 2004 American Medical Association. All Rights Reserved.
ISSN
0003-987X
eISSN
1538-3652
DOI
10.1001/archderm.140.9.1161-h
Publisher site
See Article on Publisher Site

Abstract

Diagnosis: Onchocerciasis (river blindness). Microscopic findings The excisional biopsy specimen of the subcutaneous nodule demonstrated granulomatous inflammation with numerous filariae that had thick cuticles with annulations (eccentric ringlike projections) and contained abundant microfilariae. The skin overlying the nodule displayed dermal microfilariae with lymphoeosinophilic infiltration. Discussion Onchocerciasis, caused by the filarial nematode Onchocerca volvulus, is the second leading infectious cause of blindness worldwide. Nearly all of the world's estimated 18 million infected persons live in sub-Saharan Africa.1,2 Onchocerciasis is easily misdiagnosed owing to its long incubation period and its unfamiliarity to physicians working in nonendemic areas. Clinical manifestations of onchocerciasis are found in the skin (eg, dermatitis, subcutaneous nodules, and lymphadenitis) and in the anterior and posterior chambers of the eyes (eg, keratitis and chorioretinitis). Skin findings include acute and chronic papular dermatitis, lichenified dermatitis, atrophy, depigmentation, onchocercomata (subcutaneous nodules), and inguinal lymphadenopathy.3,4 Eye findings occur exclusively among persons from endemic areas. Adult O volvulus organisms do not migrate through the eye, but motile microfilariae may be seen on slitlamp examination of the anterior chamber. In long-standing infection, sclerosing keratitis, neovascularization, and blindness may ensue.5 Like all nematodes, O volvulus has a 5-stage life cycle. Humans are the only definitive host. Worldwide disease distribution parallels the niche of Simulium black flies, which breed near fast-flowing streams. Infective larvae are inoculated subcutaneously with black fly bites; larvae mature to adult nematodes and may live 10 years within encapsulated subcutaneous or deep tissue nodules. The diagnosis of onchocerciasis is usually made by removing a small amount of dermis for direct demonstration of microfilariae (skin snip). Multiple skin snips should be obtained from affected areas (eg, scapulae, iliac crests, and lateral calf muscles) and held in saline-filled microplate wells at 37°C. Low-power microscopy reveals dermal microfilariae. Alternatively, as in this patient, excised subcutaneous nodules will demonstrate adult worms. Serologic analysis may be helpful in diagnosing expatriates (who often have negative skin snips) or in following treatment response. Polymerase chain reaction amplification of skin snips is a sensitive and specific diagnostic method for diagnosing lightly infected patients. Eosinophilia may suggest the diagnosis, but may be absent or attributable to other causes. The treatment of choice is ivermectin, which does not kill adult worms; treatment may therefore be needed for prolonged periods. Fever, pruritus, urticaria, edema, and postural hypotension may occur in persons with severe microfilaremia, but such symptoms are usually self-limited. Article Submissions Clinicians, local and regional societies, and residents and fellows in dermatology are invited to submit quiz cases to this section. Cases should follow the established pattern and be submitted double-spaced. Photomicrographs and illustrations must be clear and submitted as 3 positive color transparencies and as 3 color prints. Material should be accompanied by the required copyright transfer statement, as noted in "Instructions for Authors." Material for this section should be submitted to Michael E. Ming, MD, Department of Dermatology, University of Pennsylvania Health System, 2 Maloney Bldg, 3600 Spruce St, Philadelphia, PA 19104-4283. Reprints are not available from the authors. References 1. World Health Organization, WHO fact sheets: onchocerciasis (river blindness) Available at:http://www.who.int/health-topics/oncho.htmAccessed June 9, 2004 2. Freedman D Onchocerciasis Guerrant RLedWalker DHedWeller PFed Tropical Infectious Diseases. New York, NY Churchill Livingstone Inc1999;873- 886Google Scholar 3. McCarthy JSOttesen EANutman TB Onchocerciasis in endemic and nonendemic populations: differences in clinical presentation and immunologic findings J Infect Dis. 1994;170736- 741PubMedGoogle ScholarCrossref 4. Wortman PD Protozoan and helminth infections Harahap Med Diagnosis and Treatment of Skin Infections. Malden, Mass Blackwell Publishers1997;286- 290Google Scholar 5. Hall LRPearlman E Pathogenesis of onchocercal keratitis (river blindness) Clin Microbiol Rev. 1999;12445- 453PubMedGoogle Scholar

Journal

Archives of DermatologyAmerican Medical Association

Published: Sep 1, 2004

Keywords: adolescent,africa,onchocerciasis

References