eMedicine Specialties > Infectious Diseases > Parasitic Infections

Onchocerciasis: Differential Diagnoses & Workup

Author: Mary Nettleman, MD, MS, Chair, Department of Medicine, Michigan State University
Coauthor(s): Apoorv Kalra, MD, Assistant Professor of Medicine, Michigan State University
Contributor Information and Disclosures

Updated: Apr 16, 2009

Differential Diagnoses

Food Allergies
Pinta
Hypersensitivity Reactions, Delayed
Scabies
Leprosy
Syphilis
Lichen Planus
Treponematosis (Endemic Syphilis)
Loa loa infection
Vitamin A Deficiency
Lymphatic filariasis
Yaws

Other Problems to Be Considered

Atopic dermatitis
Contact dermatitis
Insect bites
Chronic eczema
Malnutrition
Streptocerciasis
Superficial mycoses
Glaucoma
Trachoma
Vitiligo

Workup

Laboratory Studies

  • Pathological diagnosis
    • Traditionally, a diagnosis of onchocerciasis requires demonstration of microfilariae in a skin-snip biopsy sample (see Procedures). This technique yields high specificity (100%) in experienced hands but low sensitivity (20%-50%) in early stages of infection.
    • The diagnosis may also be made by direct examination of surgical specimens obtained by excision of nodules.
  • Immunodiagnosis
    • Antibody detection does not distinguish between active and past infections. Various antibodies have been tested, as follows:
      • Ov16 card test: Antibodies against this antigen have been shown to yield high sensitivity (approximately 80%) and specificity (approximately 85%) and may yield positive results in early infections when skin-snip results are negative.20,21 Capillary blood samples are collected by finger prick. The immunochromatographic card test is used to detect the presence of immunoglobulin G4 (IgG4) antibodies to recombinant Ov16 antigen.
      • Recombinant hybrid proteins (OvH2 and OvH3): This test is based on hybrid proteins of two separate Onchocerca proteins (Ov20 and Ov33). High sensitivity (>95%) and specificity (>95%) has been described in this enzyme-linked immunoassay (ELISA)–based antibody detection test.22
      • An ELISA-based test using a cocktail of 3 antigens (Ov7, Ov11, Ov16) has also been used to detect antibodies. A comparison study showed that a mixture of these 3 proteins yielded a sensitivity of approximately 97% and a specificity 100%, superior to those of the recombinant Ov16 card test.23
      • Testing for a low–molecular-weight antigen fraction of female O volvulus parasite yields sensitivity and specificity similar to those of skin-snip testing.24
    • Antigen detection: Oncho-27 antigens have been studied in the diagnosis of Onchocerca infections. The advantage of this test is that it uses urine or tears for testing. In a study of 456 patients in a hyperendemic area of Cameroon, this technique yielded a sensitivity and specificity of 100%.25
  • Nucleic acid amplification tests: Polymerase chain reaction (PCR) using material from skin-snips or skin scratches provides high sensitivity and specificity, superior to older methods.26,3 However, the limited availability of technical expertise, as well as the high cost of the test, restricts its use in resource-limited settings.

Imaging Studies

  • Ultrasonography may reveal nonpalpable nodules, although this is not useful as a screening test. Ultrasonography of an adult worm in a nodule reveals a homogeneous echogenic area containing echodense particles with a lateral acoustic shadow.

Other Tests

  • Diethylcarbamazine (DEC) patch test: Based on the principle of Mazzotti reaction, topical application of DEC in a cream base (DEC patch) elicits localized cutaneous reactions (pruritus, maculopapular eruptions, dermal edema) in response to dying microfilariae.27 Earlier studies reported varying degree of sensitivity (30%-92%) in patients with positive skin-snip results. Severe cutaneous reactions may require steroid therapy or hospitalization. Higher concentrations of DEC and longer patch times increase the sensitivity.28 However, false-positive reactions may occur in patients with other filarial diseases such as Loa loa infection.

Procedures

  • Skin snip
    • In this technique, a razor blade is used to remove tiny skin samples (3-5 mg) from multiple sites (iliac crests, shoulder blades); they are then placed in saline to observe microfilariae emerging from the skin samples. Alternatively, sclerocorneal punch samples can be used to obtain skin-tissue specimens.
    • The sensitivity is low in the prepatent disease stage, areas of low prevalence, and areas of mass ivermectin use.
    • Skin-snip biopsy specimens can also be used to detect microfilariae using nucleic acid amplification.
  • Nodule resection (nodulectomy, onchocercomectomy): Although this is the most invasive method, surgical removal of nodules has both diagnostic (if adult worm is observed) and therapeutic potential (elimination of the adult worms in that nodule).

Histologic Findings

Microscopic examination of excised onchocercomata reveals cross-sections of adult worms with eosinophils and lymphocytes at the periphery of the nodule.

More on Onchocerciasis

Overview: Onchocerciasis
Differential Diagnoses & Workup: Onchocerciasis
Treatment & Medication: Onchocerciasis
Follow-up: Onchocerciasis
Multimedia: Onchocerciasis
References
[ CLOSE WINDOW ]

References

  1. Burnham G. Onchocerciasis. Lancet. May 2 1998;351(9112):1341-6. [Medline].

  2. Hoerauf A, Büttner DW, Adjei O, Pearlman E. Onchocerciasis. BMJ. Jan 25 2003;326(7382):207-10. [Medline].

  3. Udall DN. Recent updates on onchocerciasis: diagnosis and treatment. Clin Infect Dis. Jan 1 2007;44(1):53-60. [Medline].

  4. Klion AD. Filarial infections in travelers and immigrants. Curr Infect Dis Rep. Mar 2008;10(1):50-7. [Medline].

  5. Nguyen JC, Murphy ME, Nutman TB, Neafie RC, Maturo S, Burke DS. Cutaneous onchocerciasis in an American traveler. Int J Dermatol. Feb 2005;44(2):125-8. [Medline].

  6. World Health Organization. Onchocerciasis (river blindness). Wkly Epidemiol Rec. Jul 6 2001;76(27):205-10. [Medline].

  7. World Health Organization. Onchocerciasis and its control. Report of a WHO Expert Committee on Onchocerciasis Control. World Health Organ Tech Rep Ser. 1995;852:1-104. [Medline].

  8. World Health Organization. Onchocerciasis (river blindness). Report from the Fourteenth InterAmerican Conference on Onchocerciasis, Atlanta, Georgia, United States. Wkly Epidemiol Rec. Jul 29 2005;80(30):257-60. [Medline].

  9. World Health Organization. Onchocerciasis (river blindness). Wkly Epidemiol Rec. Jul 6 2001;76(27):205-10. [Medline].

  10. Dimomfu BL, Lubeji DK, Noma M, Sékétéli A, Boussinesq M. African Programme for Onchocerciasis Control (APOC): sociological study in three foci of central Africa before the implementation of treatments with ivermectin (Mectizan). Trans R Soc Trop Med Hyg. Jul 2007;101(7):674-9. [Medline].

  11. Hotez PJ. Control of onchocerciasis--the next generation. Lancet. Jun 16 2007;369(9578):1979-80. [Medline].

  12. Sauerbrey M. The Onchocerciasis Elimination Program for the Americas (OEPA). Ann Trop Med Parasitol. Sep 2008;102 Suppl 1:25-9. [Medline].

  13. Amazigo U. The African Programme for Onchocerciasis Control (APOC). Ann Trop Med Parasitol. Sep 2008;102 Suppl 1:19-22. [Medline].

  14. Boatin B. The Onchocerciasis Control Programme in West Africa (OCP). Ann Trop Med Parasitol. Sep 2008;102 Suppl 1:13-7. [Medline].

  15. Pion SD, Kamgno J, Demanga-Ngangue, Boussinesq M. Excess mortality associated with blindness in the onchocerciasis focus of the Mbam Valley, Cameroon. Ann Trop Med Parasitol. Mar 2002;96(2):181-9. [Medline].

  16. Enk CD. Onchocerciasis--river blindness. Clin Dermatol. May-Jun 2006;24(3):176-80. [Medline].

  17. Kayembe DL, Kasonga DL, Kayembe PK, Mwanza JC, Boussinesq M. Profile of eye lesions and vision loss: a cross-sectional study in Lusambo, a forest-savanna area hyperendemic for onchocerciasis in the Democratic Republic of Congo. Trop Med Int Health. Jan 2003;8(1):83-9. [Medline].

  18. Timmann C, van der Kamp E, Kleensang A, König IR, Thye T, Büttner DW, et al. Human genetic resistance to Onchocerca volvulus: evidence for linkage to chromosome 2p from an autosome-wide scan. J Infect Dis. Aug 1 2008;198(3):427-33. [Medline].

  19. Kayembe DL, Kasonga DL, Kayembe PK, Mwanza JC, Boussinesq M. Profile of eye lesions and vision loss: a cross-sectional study in Lusambo, a forest-savanna area hyperendemic for onchocerciasis in the Democratic Republic of Congo. Trop Med Int Health. Jan 2003;8(1):83-9. [Medline].

  20. Lipner EM, Dembele N, Souleymane S, Alley WS, Prevots DR, Toe L, et al. Field applicability of a rapid-format anti-Ov-16 antibody test for the assessment of onchocerciasis control measures in regions of endemicity. J Infect Dis. Jul 15 2006;194(2):216-21. [Medline].

  21. Weil GJ, Steel C, Liftis F, Li BW, Mearns G, Lobos E. A rapid-format antibody card test for diagnosis of onchocerciasis. J Infect Dis. Dec 2000;182(6):1796-9. [Medline].

  22. Nde PN, Pogonka T, Bradley JE, Titanji VP, Lucius R. Sensitive and specific serodiagnosis of onchocerciasis with recombinant hybrid proteins. Am J Trop Med Hyg. May 2002;66(5):566-71. [Medline].

  23. Rodríguez-Pérez MA, Domínguez-Vázquez A, Méndez-Galván J, Sifuentes-Rincón AM, Larralde-Corona P, Barrera-Saldaña HA, et al. Antibody detection tests for Onchocerca volvulus: comparison of the sensitivity of a cocktail of recombinant antigens used in the indirect enzyme-linked immunosorbent assay with a rapid-format antibody card test. Trans R Soc Trop Med Hyg. Sep-Oct 2003;97(5):539-41. [Medline].

  24. Guzmán GE, Lavebratt C, Luján R, Akuffo H. Diagnosis of onchocerciasis using highly specific and sensitive native proteins. Scand J Infect Dis. 2002;34(8):583-90. [Medline].

  25. Ayong LS, Tume CB, Wembe FE, Simo G, Asonganyi T, Lando G. Development and evaluation of an antigen detection dipstick assay for the diagnosis of human onchocerciasis. Trop Med Int Health. Mar 2005;10(3):228-33. [Medline].

  26. Boatin BA, Toé L, Alley ES, Dembélé N, Weiss N, Dadzie KY. Diagnostics in onchocerciasis: future challenges. Ann Trop Med Parasitol. Apr 1998;92 Suppl 1:S41-5. [Medline].

  27. Ozoh G, Boussinesq M, Bissek AC, Kobangue L, Kombila M, Mbina JR, et al. Evaluation of the diethylcarbamazine patch to evaluate onchocerciasis endemicity in Central Africa. Trop Med Int Health. Jan 2007;12(1):123-9. [Medline].

  28. Toè L, Adjami AG, Boatin BA, Back C, Alley ES, Dembélé N. Topical application of diethylcarbamazine to detect onchocerciasis recrudescence in west Africa. Trans R Soc Trop Med Hyg. Sep-Oct 2000;94(5):519-25. [Medline].

  29. Basáñez MG, Pion SD, Boakes E, Filipe JA, Churcher TS, Boussinesq M. Effect of single-dose ivermectin on Onchocerca volvulus: a systematic review and meta-analysis. Lancet Infect Dis. May 2008;8(5):310-22. [Medline].

  30. Reddy M, Gill SS, Kalkar SR, Wu W, Anderson PJ, Rochon PA. Oral drug therapy for multiple neglected tropical diseases: a systematic review. JAMA. Oct 24 2007;298(16):1911-24. [Medline].

  31. Hoerauf A, Mand S, Volkmann L, Büttner M, Marfo-Debrekyei Y, Taylor M, et al. Doxycycline in the treatment of human onchocerciasis: Kinetics of Wolbachia endobacteria reduction and of inhibition of embryogenesis in female Onchocerca worms. Microbes Infect. Apr 2003;5(4):261-73. [Medline].

  32. Hoerauf A, Specht S, Büttner M, Pfarr K, Mand S, Fimmers R, et al. Wolbachia endobacteria depletion by doxycycline as antifilarial therapy has macrofilaricidal activity in onchocerciasis: a randomized placebo-controlled study. Med Microbiol Immunol. Sep 2008;197(3):295-311. [Medline].

  33. Hoerauf A, Mand S, Adjei O, Fleischer B, Büttner DW. Depletion of wolbachia endobacteria in Onchocerca volvulus by doxycycline and microfilaridermia after ivermectin treatment. Lancet. May 5 2001;357(9266):1415-6. [Medline].

  34. Specht S, Mand S, Marfo-Debrekyei Y, Debrah AY, Konadu P, Adjei O, et al. Efficacy of 2- and 4-week rifampicin treatment on the Wolbachia of Onchocerca volvulus. Parasitol Res. Nov 2008;103(6):1303-9. [Medline].

  35. Hoerauf A, Marfo-Debrekyei Y, Büttner M, Debrah AY, Konadu P, Mand S, et al. Effects of 6-week azithromycin treatment on the Wolbachia endobacteria of Onchocerca volvulus. Parasitol Res. Jul 2008;103(2):279-86. [Medline].

[ CLOSE WINDOW ]

Further Reading

[ CLOSE WINDOW ]

Keywords

onchocerciasis, onchocercosis, river blindness, volvulosis, craw-craw, Robles disease, Onchocerca volvulus, O volvulus, Simulium fly, blinding disease, papular dermatitis, leopard skin, sowda, sowdah, Nakalaga syndrome, ocular onchocerciasis, ocular onchocercosis, onchodermatitis, onchocercomata

[ CLOSE WINDOW ]

Contributor Information and Disclosures

Author

Mary Nettleman, MD, MS, Chair, Department of Medicine, Michigan State University
Mary Nettleman, MD, MS is a member of the following medical societies: American College of Physicians, Association of Professors of Medicine, Central Society for Clinical Research, Infectious Diseases Society of America, and Society of General Internal Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Apoorv Kalra, MD, Assistant Professor of Medicine, Michigan State University
Disclosure: Nothing to disclose.

Medical Editor

Daniel R Lucey, MD, MPH, Chief, Fellowship Program Director, Department of Internal Medicine, Division of Infectious Diseases, Washington Hospital Center; Professor, Department of Internal Medicine, Uniformed Services University of the Health Sciences
Daniel R Lucey, MD, MPH is a member of the following medical societies: Alpha Omega Alpha and American College of Physicians
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

John W King, MD, Professor of Medicine, Section of Infectious Diseases, Louisiana State University Health Sciences Center; Director, Viral Therapeutics Clinics for Hepatitis; Consulting Staff, Department of Infectious Diseases, Overton Brook Veterans Affairs Medical Center
John W King, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Federation for Medical Research, American Society for Microbiology, Association of Subspecialty Professors, Infectious Diseases Society of America, and Sigma Xi
Disclosure: emedicine $50.00 author of chapter

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

 
 
HONcode

We subscribe to the
HONcode principles of the
Health On the Net Foundation

All material on this website is protected by copyright, Copyright© 1994- by Medscape.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.