- Author: Hassan I Galadari, MD; Chief Editor: William D James, MD more...
The diagnosis of yaws is made by clinical evaluation of lesions and is confirmed by the detection of treponemes on dark-field microscopy of serum obtained by squeezing the bases of the lesions.
Radiologic studies are nonspecific but can include any of the following findings:
Surface striations (periostitis)
Cortical thickening with bowing (saber shin deformity)
Spiculated periosteal reaction
General osseous expansion
Stellate frontal bone scans
Serologic tests for yaws are identical to those for venereal syphilis, including rapid plasma reagent (RPR) test, Venereal Disease Research Laboratory (VDRL) test, fluorescent treponemal antibody absorption (FTA-ABS) test, T pallidum immobilization (TPI) test, and T pallidum hemagglutination assay (TPHA). RPR and VDRL tests are reactive 2-3 weeks after the onset of the primary lesion, and they generally remain reactive throughout all stages.
No serologic test can distinguish yaws from other nonvenereal treponematoses; therefore, diagnosis is ultimately based on correlation of the clinical findings, epidemiologic history, and positive serologic results that are suggestive of yaws. Biopsy of late lesions may be needed to show characteristic histopathology.
Histologic findings in early yaws include acanthosis, papillomatosis, and spongiosis. Treponemes are found in the epidermidis. Neutrophilic exocytosis with intraepidermal microabscess formation is the most characteristic finding. The dermis has a moderate to dense granulomatous infiltrate that is mainly composed of plasma cells and lymphocytes, with few histiocytes, neutrophils, and eosinophils. Unlike syphilis, endothelial proliferation is absent or low.
Late yaws has histologic findings similar to those of tertiary syphilis, including an intense dermal infiltrate composed of epithelioid cells, giant cells, lymphocytes, and fibroblasts. Caseation necrosis can also be observed. Plasma cells and histiocytes, in contrast to early yaws, are scarce.
Silver stains (Steiner) can be used to identify numerous treponemes between keratinocytes in early yaws. They are seen in a bandlike pattern or in clusters in the epidermis. Unlike T pallidum, which is found in both the epidermis and the dermis, T pallidumpertenue is almost entirely epidermotropic.
Electron microscopy of early lesions demonstrates scarce treponemes in clusters in the intercellular spaces of the epidermis among inflammatory cells, within the cytoplasm of macrophages, and in the dermis.
Koff AB, Rosen T. Nonvenereal treponematoses: yaws, endemic syphilis, and pinta. J Am Acad Dermatol. 1993 Oct. 29(4):519-35; quiz 536-8. [Medline].
Sanchez MR. Endemic (Nonvenereal) Treponematoses. Freedberg IM, Eisen AZ, Wolff K, Austen F, Goldsmith LA, Katz S, eds. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003.
Yaws eradication: past efforts and future perspectives. Available at http://www.who.int/bulletin/volumes/86/7/08-055608/en/. Accessed: July 30, 2012.
Lupi O, Madkan V, Tyring SK. Tropical dermatology: bacterial tropical diseases. J Am Acad Dermatol. 2006 Apr. 54(4):559-78; quiz 578-80. [Medline].
Gerstl S, Kiwila G, Dhorda M, et al. Prevalence study of yaws in the Democratic Republic of Congo using the lot quality assurance sampling method. PLoS One. 2009 Jul 22. 4(7):e6338. [Medline]. [Full Text].
Guerrier G, Marcon S, Garnotel L, Deltour R, Schinas S, Mathelin JP, et al. Yaws in Polynesia's Wallis and Futuna Islands: a seroprevalence survey. N Z Med J. 2011 Apr 29. 124(1333):29-31. [Medline].
Consultation on yaws elimination 5-7 March 2012, WHO Headquarters, Geneva, Room M505. Available at http://www.who.int/neglected_diseases/NTD_RoadMap_2012_Fullversion.pdf. Accessed: July 30, 2012.
Maurice J. WHO plans new yaws eradication campaign. Lancet. 2012 Apr 14. 379(9824):1377-8. [Medline].
Mitjà O, Hays R, Ipai A, Penias M, Paru R, Fagaho D, et al. Single-dose azithromycin versus benzathine benzylpenicillin for treatment of yaws in children in Papua New Guinea: an open-label, non-inferiority, randomised trial. Lancet. 2012 Jan 28. 379(9813):342-7. [Medline].
Agmon-Levin N, Bat-sheva PK, Barzilai O, et al. Antitreponemal antibodies leading to autoantibody production and protection from atherosclerosis in Kitavans from Papua New Guinea. Ann N Y Acad Sci. 2009 Sep. 1173:675-82. [Medline].
Mitjà O, Hays R, Ipai A, Gubaila D, Lelngei F, Kiara M, et al. Outcome predictors in treatment of yaws. Emerg Infect Dis. 2011 Jun. 17(6):1083-5. [Medline].
Etymologia: yaws. Emerg Infect Dis. 2011 Jun. 17(6):1082. [Medline].
Rothschild BM, Heathcote GM. Characterization of the skeletal manifestations of the treponemal disease yaws as a population phenomenon. Clin Infect Dis. 1993 Aug. 17(2):198-203. [Medline].
Fegan D, Glennon MJ, Thami Y, Pakoa G. Resurgence of yaws in Tanna, Vanuatu: time for a new approach?. Trop Doct. 2010 Apr. 40(2):68-9. [Medline].
Engelkens HJ, ten Kate FJ, Judanarso J, et al. The localisation of treponemes and characterisation of the inflammatory infiltrate in skin biopsies from patients with primary or secondary syphilis, or early infectious yaws. Genitourin Med. 1993 Apr. 69(2):102-7. [Medline].
Farnsworth N, Rosen T. Endemic treponematosis: review and update. Clin Dermatol. 2006 May-Jun. 24(3):181-90. [Medline].
Scolnik D, Aronson L, Lovinsky R, Toledano K, Glazier R, Eisenstadt J, et al. Efficacy of a targeted, oral penicillin-based yaws control program among children living in rural South America. Clin Infect Dis. 2003 May 15. 36(10):1232-8. [Medline].
Manirakiza A, Boas SV, Beyam NE, Zadanga G, Konamna FX, Njuimo SP, et al. Clinical outcome of skin yaws lesions after treatment with benzathinebenzylpenicillin in a pygmy population in Lobaye, Central African Republic. BMC Res Notes. 2011 Dec 15. 4(1):543. [Medline].
Mitjà O, Hays R, Rinaldi AC, McDermot R, Bassat Q. New treatment schemes for yaws: the path toward eradication. Clin Infect Dis. 2012 Aug. 55(3):406-12. [Medline].