Etiology Epidemiology and Clinical Manifestations

Because the treponemas that cause yaws, nonvenereal syphilis, pinta (an American disease), and syphilis are morphologically and serologically indistinguishable, it is believed that at least the Old World diseases may represent an evolutionary continuum running from south to north. Yaws, thought to be the oldest, spreads by skin-to-skin contact and flourishes in the hot and moist regions of Africa south of the Sahara where individuals have historically worn little clothing. Syphilis, by contrast, seems to be the newest of the treponematoses. Venereal transmission allows it to spread among peoples of colder climates whose clothing would frustrate skin-to-skin transmission.

Bejel or nonvenereal syphilis seems to be intermediate between the two both bacteriologically and geographically. It has been conceived of as yaws modified by a desert environment, and as juvenile, nonvenereal syphilis. It is not transmitted congeni-tally. The disease spreads from child to child in dry, mostly rural areas where a lack of cleanliness facili tates transmission. The spirochetes of nonvenereal syphilis, like those of yaws and syphilis, perish in the presence of atmospheric oxygen, soaps, detergents, and antiseptics, and are very sensitive to drying. T. pallidum is able to penetrate mucous membranes, but intact skin presents it with a formidable barrier. The primary lesion is often in the region of the mouth, probably the result of sharing drinking vessels or eating utensils or by direct mouth-to-mouth contact. It can also spread from direct nonsexual contact, and flies, lice, and fleas may also have a role in transmission.

The stages of the disease - primary, secondary, and late or tertiary — are not so pronounced as are those of syphilis. In the case of bejel, the primary lesion is soon followed by the appearance of moist papules in skin folds and by drier lesions on the trunk and extremities. Late lesions, when they occur, can be ugly. Huge ulcers may form, and ulceration of the palatal and nasal bones can cause them to erode. Other possible physical symptoms are changes in pigment distribution and in the deformity of other bones, especially long bones such as the tibia.

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