106 Pinta
Pinta (meaning “spotted”) is also called mal de pinto and carate. It is the least destructive of the trepone- matoses that are pathogenic for humans. Although the taxonomy of these treponemes is by no means resolved, pinta is sufficiently distinctive to argue for a separate causal species, Treponema carateum.
As a specific treponemal variety, it was not described until 1938. The disease is chronic, predominantly affects the skin, and is now found only among isolated rural groups in Central and South America and Mexico, where it is endemic. Local names for the illness are tiha, empeines, and vitiligo.Distribution and Incidence
According to one historian of treponemal diseases, pinta may have had a considerable world distribution at the end of the Paleolithic period, some 10,000 years ago. However, its past geographic distribution is in some doubt, and an alternative view suggests that it may have evolved purely in Amerindian communities of the New World, as a final level of microevolutionary change in the treponematoses there. Because it is not a very destructive condition, and may remain untreated in many individuals of the Third World countries of Latin America, it has been estimated that as many as a million individuals may have the disease.
Epidemiology and Etiology
Pinta is caused by T. carateum, which cannot be distinguished from Treponema pallidum (the causative agent of endemic and venereal syphilis). These treponemes are found mainly in the lower Malpighian layers of the epidermis, and may be present for years before the skin lesions eventually become inactive and depigmented. Large areas may be infected, and the disease may remain infectious for a long period. It is unusual for other areas of the body, such as the genitals, to be involved. In contrast to the other human treponematoses, the skeleton is never affected.
This chronic clinical condition usually begins in childhood and lasts into adulthood, if not for most of the lifetime of an infected individual. Social and hygienic factors result in the differential incidence of the disease in varying components of Latin American societies, with native Indians, mestizos, and blacks being most affected. Infection seems most likely to be by skin contact. Insect vectors have also been suggested as a means of transmission, but this has not been substantiated.
Immunology
Serologic reactions are positive early, then increase in degree. Experiments show that there is crossimmunity to a varying extent in individuals infected with T carateum, T. pallidum, and Treponema pertenue.
Clinical Manifestations and Pathology
There is no chancre, and the condition begins as an extragenital papule, usually situated in the lower extremity (and perhaps associated with damage to the skin surface). Within 3 weeks, the papule has expanded into a reactive patch of circinate form, termed a pintid. In the next few months, a more general rash occurs on the face and limbs, which can be similar in appearance to such diseases as psoriasis, ringworm, and eczema.
Histologically, hyperkeratosis and intercellular edema are evident, with an increase of lymphocytes and plasma cells. In adults, there are usually pigmentary changes in the later stages. Bluish patches are perhaps most characteristic, but lesions may be white. Pigmentary function is clearly disturbed, and in the white patches pigment is absent. It should be emphasized that other treponematoses can start out to some extent like pinta, but that the others progress beyond purely skin changes. The disease is not transmitted to the fetus.
History and Geography
Pinta is believed to be most prevalent in Mexico, Venezuela, Colombia, Peru, and Ecuador. It is an “old” disease in the Americas, clearly present before the arrival of the Europeans. Although a relatively mild disease, it has tended historically to evoke a variety of social responses.
In some instances the pintados or “spotted ones” have been shunned, much like lepers in the Old World. Yet in other circumstances their distinctive appearance has brought them high status. For example, Montezuma, the Aztec emperor, selected such individuals to bear his litter, and they were apparently frequently formed into special and elite battalions in Mexican history.It appears, however, that the earliest recognizable description of pinta as a separate disease was not recorded until 1757 in Mexico. Because of the possible similarities to leprosy in regard to the skin changes, it is not so surprising that a medical commission in 1811 reported on it as leprosy. In 1889 pinta was viewed as perhaps linked to syphilis and was thought to be transmitted by venereal contact. Indeed, this hypothesis seemed to “square” with accounts that reported the efficacy of mercury in the treatment of pinta, and the fact that infected individuals who worked in mercury mines felt better. The positive Wassermann reaction was demonstrated in 1925, but the true nature of this distinctive treponemal condition was not recognized until 1938.
Don R. Brothwell
Bibliography
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