Yaws, caused by Treponema pallidum subsp. pertenue, is an important public health problem in many tropical countries.1 Like syphilis, the disease manifests in three stages; however, unlike syphilis, its route of transmission is non-genital skin-to-skin contact and not by sexual intercourse. Primary yaws manifests as either a papilloma or a chronic ulcer. Typically, ulcers are painless, with a raised edge and friable base (Figure 1). In secondary yaws, skin manifestations, involvement of the bones and joints including periostitis have been reported. Tertiary yaws develops in a minority of patients causing destructive lesions of the skin and soft tissues. Interest in yaws has been revived by the finding that azithromycin is a highly effective treatment of both primary and secondary yaws.2 Clinical diagnosis alone of primary yaws is unreliable, but a point-of-care test has been shown to be of value.3 This test provides a result analogous to a T. pallidum particle agglutination assay (Figure 2, line 1) and a rapid plasma reagin (RPR) assay (Figure 2, line 2). In early infection, only the RPR may be positive. Diagnosis has been further complicated by the discovery that Haemophilus ducreyi may cause clinically similar ulcers.4 New polymerase chain reaction (PCR) assays have been developed for yaws.5 DNA suitable for can be extracted directly from swabs collected into dry tubes without the need for transport medium. Figure 3 demonstrates real-time PCR amplification curves of positive and negative controls and a clinical swab from a yaws lesion containing T. pallidum pertenue DNA. Both serological and molecular tests have a major role to play in the World Health Organization yaws eradication campaign.
Classical primary ulcer of yaws.
Citation: The American Society of Tropical Medicine and Hygiene 96, 1; 10.4269/ajtmh.16-0639
Combined treponemal and nontreponemal rapid diagnostic test for yaws.
Citation: The American Society of Tropical Medicine and Hygiene 96, 1; 10.4269/ajtmh.16-0639
Quantitative polymerase chain reaction for yaws.
Citation: The American Society of Tropical Medicine and Hygiene 96, 1; 10.4269/ajtmh.16-0639
- 1.↑
Marks M, Solomon AW, Mabey DC, 2014. Endemic treponemal diseases. Trans R Soc Trop Med Hyg 108: 601–607.
- 2.↑
Mitjà O, Hays R, Ipai A, Penias M, Paru R, Fagaho D, de Lazzari E, Bassat Q, 2012. Single-dose azithromycin versus benzathine benzylpenicillin for treatment of yaws in children in Papua New Guinea: an open-label, non-inferiority, randomised trial. Lancet 379: 342–347.
- 3.↑
Marks M, Goncalves A, Vahi V, Sokana O, Puiahi E, Zhang Z, Dalipanda T, Bottomley C, Mabey D, Solomon AW, 2014. Evaluation of a rapid diagnostic test for yaws infection in a community surveillance setting. PLoS Negl Trop Dis 8: e3156.
- 4.↑
Marks M, Chi K-H, Vahi V, Pillay A, Sokana O, Pavluck A, Mabey DC, Chen CY, Solomon AW, 2014. Haemophilus ducreyi associated with skin ulcers among children, Solomon Islands. Emerg Infect Dis 20: 1705–1707.
- 5.↑
Mitjà O, Lukehart SA, Pokowas G, Moses P, Kapa A, Godornes C, Robson J, Cherian S, Houinei W, Kazadi W, Siba P, de Lazzari E, Bassat Q, 2014. Haemophilus ducreyi as a cause of skin ulcers in children from a yaws-endemic area of Papua New Guinea: a prospective cohort study. Lancet Glob Health 2: e235–e241.