Spirochetes are distinguished by the helical shape of the bacteria. Pathogenic spirochetes include Treponema, Leptospira, and Borrelia. Both Treponema and Leptospira are too thin to be seen using brightfield microscopy but are clearly seen using darkfield or phase microscopy. Borrelia are thicker and can also be stained and seen using brightfield microscopy.
For bejel, pinta, and yaws, the causative agents are
These Treponema species are morphologically and serologically indistinguishable from the agent of syphilis, T. pallidum subspecies pallidum. As in syphilis, the typical course is an initial mucocutaneous lesion followed by diffuse secondary lesions, a latent period, and late destructive disease.
Transmission is by close skin contact—sexual or not—primarily between children living in conditions of poor hygiene.
Bejel (endemic syphilis) occurs mainly in hot, dry regions of the eastern Mediterranean and Saharan West Africa. Transmission results from mouth-to-mouth contact or sharing eating and drinking utensils.
Yaws (frambesia) is the most prevalent of the endemic treponematoses and occurs in humid equatorial countries. Transmission requires direct skin contact and is favored by skin trauma.
Pinta, which is more limited in geographical distribution, occurs among the natives of Mexico, Central America, and South America and is not very contagious. Transmission probably requires contact with broken skin.
Unlike T. pallidum subspecies pallidum, other human treponemal subspecies are not transmitted via blood or transplacentally.
Bejel begins in childhood as a mucous patch (usually on the buccal mucosa), which may go unnoticed, or as stomatitis at the angles of the lips. These painless lesions may resolve spontaneously but are usually followed by papulosquamous and erosive papular lesions of the trunk and extremities that are similar to yaws. Periostitis of the leg bones is common. Later, gummatous lesions of the nose and soft palate develop.
Yaws, after an incubation period of several weeks, begins at the site of inoculation as a red papule that enlarges, erodes, and ulcerates (primary yaws). The surface resembles a strawberry, and the exudate is rich in spirochetes. Local lymph nodes may be enlarged and tender. The lesion heals but is followed after months to a year by successive generalized eruptions that resemble the primary lesion (secondary yaws). These lesions often develop in moist areas of the axillae, skinfolds, and mucosal surfaces; they heal slowly and may recur. Keratotic lesions may develop on the palms and soles, causing painful ulcerations (crab yaws). Five to 10 years later, destructive lesions (tertiary yaws) may develop; they include the following:
Pinta lesions are confined to the dermis. They begin at the inoculation site as a small papule that enlarges and becomes hyperkeratotic; they develop mainly on the extremities, face, and neck. After 3 to 9 months, further thickened and flat lesions (pintids) appear all over the body and over bony prominences. Still later, some lesions become slate blue or depigmented, resembling vitiligo. Pinta lesions typically persist if not treated.
Diagnosis of endemic treponematoses is based on the typical appearance of lesions in people from endemic areas.
Both nontreponemal and treponemal serologic tests for syphilis (the Venereal Disease Research Laboratory [VDRL], rapid plasma reagin [RPR], and fluorescent treponemal antibody absorption tests [FTA-ABS]) are positive; thus, differentiation from venereal syphilis is clinical. Early lesions are often darkfield-positive for spirochetes and are indistinguishable from T. pallidum subspecies pallidum.
Active disease is treated with 1 dose of penicillin benzathine 1.2 million units IM. Children < 45 kg should receive 600,000 units IM. A single dose of azithromycin 30 mg/kg orally (maximum 2 g) or doxycycline 100 mg orally twice a day for 14 days is an alternative for penicillin-allergic adults.
Public health control includes active case finding and treatment of family and close contacts with penicillin benzathine or doxycycline to prevent infection from developing.
The Treponema species that cause bejel, pinta, and yaws are morphologically and serologically indistinguishable from the agent of syphilis, T. pallidum subspecies pallidum.
Disease is spread by close body contact, typically between children living in conditions of poor hygiene.
As in syphilis, the typical course is an initial mucocutaneous lesion, followed by diffuse secondary lesions, a latent period, and late destructive disease.
Serologic tests for syphilis (including fluorescent treponemal antibody absorption tests) are positive; thus, differentiation from venereal syphilis is clinical.
Give 1 dose of penicillin benzathine IM or, for penicillin-allergic adults, 1 dose of azithromycin 30 mg/kg orally (maximum 2 g) or 2 weeks of doxycycline 100 mg orally twice a day.
Treat close contacts with antibiotics.