Background
Yaws is a contagious, nonvenereal, treponemal infection in humans that mainly occurs in children younger than 15 years. Infection with Treponema pertenue, a subspecies of Treponema pallidum, causes the disease, which occurs primarily in warm, humid, tropical areas of Africa, Asia, South America, and Oceania among poor rural populations where conditions of overcrowding and poor sanitation prevail.
Pathophysiology
The major route of infection is through direct person-to-person contact. The treponemes associated with yaws are located primarily in the epidermis. The ulcerative skin lesions that develop early in the disease course are teeming with spirochetes, which can be transmitted via direct skin-to-skin contact and via breaks in the skin due to trauma, bites, or excoriations.
Yaws, like syphilis, has been classified into the following 4 stages:
Primary stage: The initial yaws lesion develops at the inoculation site.
Secondary stage: Widespread dissemination of treponemes results in multiple skin lesions similar to the primary yaws lesion.
Latent stage: Symptoms are usually absent, but skin lesions can relapse.
Tertiary stage: Bone, joint, and soft tissue deformities may occur.
Another classification distinguishes early yaws from late yaws. Early yaws includes primary and secondary stages and is characterized by the presence of contagious skin lesions. Late yaws includes the tertiary stage, when lesions are not contagious.
Epidemiology
Frequency
United States
Yaws does not occur in the United States.
International
An estimated 50-100 million persons were infected with yaws before mass treatment campaigns in the 1950s. In the 1970s, yaws cases declined to fewer than 2 million. In the 1980s, fewer than 500 cases per year were reported in the Western Hemisphere. A resurgence of yaws has occurred in West and Central Africa, Southeast Asia, and the Pacific Islands, with recent outbreaks in Thailand, India, Indonesia, Papua New Guinea, and the Solomon Islands. Sporadic cases are reported in South America.
Mortality/Morbidity
In most patients, yaws remains limited to the skin, but early bone and joint involvement can occur. Although yaws lesions disappear spontaneously, secondary bacterial infections and scarring are common complications.
After 5-10 years, 10% of untreated patients develop destructive lesions that involve bone, cartilage, skin, and soft tissue, similar to those seen in tertiary syphilis. In contrast to venereal syphilis, cardiovascular and neurological abnormalities almost never occur in patients with yaws.
Sex
Age
Histologic Findings
Typical histopathology of early yaws shows papillomatous epidermal hyperplasia, focal spongiosis, and intraepidermal microabscesses. Treponemes are found in the epidermidis. See the images below.
View Image | Early yaws papillomata (from Perine PL, Hopkins DR, Niemel PLA, et al. Handbook of Endemic Treponematoses: Yaws, Endemic Syphilis, and Pinta. Geneva, .... |
View Image | Early ulceropapillomatous yaws on the leg (from Perine PL, Hopkins DR, Niemel PLA, et al. Handbook of Endemic Treponematoses: Yaws, Endemic Syphilis, .... |
Medication Summary
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Penicillin G benzathine (Bicillin)
Clinical Context:
Interferes with cell wall synthesis during active multiplication, resulting in bactericidal activity against susceptible microorganisms.
Tetracycline (Achromycin, Sumycin)
Clinical Context:
Avoid benzathine penicillin in patients allergic to penicillin; tetracycline or erythromycin is alternate therapy.
Erythromycin (Erythrocin, E-Mycin, E.E.S.)
Clinical Context:
Inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest. For treatment of staphylococcal and streptococcal infections. Indicated for the treatment of infections in children allergic to penicillin or in pregnant women.
Class Summary
Benzathine penicillin is the DOC for treating yaws. In remote areas where benzathine penicillin is unavailable, oral penicillin V for 7-10 days can reduce the prevalence of yaws and is effective in treating individual children with active lesions.[1]
Author
Natalie C Klein, MD, PhD, Associate Director, Infectious Disease Division, Associate Professor of Medicine, The School of Medicine at Stony Brook University Medical Center
Disclosure: Nothing to disclose.
Specialty Editors
Gary L Gorby, MD, Associate Professor, Departments of Internal Medicine and Medical Microbiology and Immunology, Division of Infectious Diseases, Creighton University School of Medicine; Associate Professor of Medicine, University of Nebraska Medical Center; Associate Chair, Omaha Veterans Affairs Medical Center
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Medscape Salary Employment
Richard B Brown, MD, FACP, Chief, Division of Infectious Diseases, Baystate Medical Center; Professor, Department of Internal Medicine, Tufts University School of Medicine
Disclosure: Nothing to disclose.
Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
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
Disclosure: Nothing to disclose.
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