# Tropical Diseases/Chapter 37

CHAPTER XXXVII
YAWS (FRAMBŒSIA)
Definition.— Yaws is a contagious inoculable disease characterized by an indefinite incubation period followed usually by fever, by rheumatic-like pains, and by the appearance of papules which generally develop into a fungating, encrusted, granuloniatous eruption. It runs a chronic course; is mostly protective against a second attack; is believed to be caused by Treponema pertenue; is amenable to salvarsan, and, to a certain extent, is influenced by mercury and potassium iodide.
Geographical distribution.— Yaws is widely diffused throughout the greater part of the tropical world. In certain places it is very common— as in tropical Africa, particularly on the west coast; in many of the West India Islands; in Ceylon, where it is one of perhaps several diseases included under the term parangi; in Fiji, where it is known as coko; in Java; in Samoa; and in many of the islands of the Pacific. It is difficult to say to what extent it exists in India; some deny its presence there altogether, but recent observations show that it does occur there to a limited extent; Powell has recognized and described it as occurring in Assam. Barker and Gimlette have shown that the skin disease described by Brown under the name of purru, and common in parts of the Malay Peninsula, is yaws. Yaws occurs in China, but is rare there— at all events on the coast. In some of the West India Islands, and Fiji, almost every child passes through an attack. In the latter, according to Daniels, those children who do not acquire the disease in the ordinary way are inoculated with it by their parents, who regard an attack of yaws as an occurrence more or less necessary and wholesome. Nicholls has made a ​careful and admirable study of West Indian yaws. His inclination is to look upon parangi, coko, and similar Asiatic and Pacific island diseases as specifically different from the African and West Indian disease. Daniels, however— a most accurate observer, who has had extensive experience in Fiji, in British Guiana, and in Africa— shows very clearly that in these places the diseases are identical. Probably the view that certain forms of the parangi of Ceylon are not yaws is likewise incorrect.
It is impossible at the present day to settle the point, but it seems probable that yaws was originally an African disease, and, so far as America and the West Indies are concerned, that it was introduced by negro slaves. In the days of West Indian slavery the specific and infectious nature of yaws was thoroughly recognized. The planters, from economic apart from other considerations, by instituting yaws-houses and similar repressive measures, took much trouble to keep the disease under. Since emancipation has permitted the West Indian negro to revert to some extent to the state of savagery from which he had partly emerged, yaws has again become very prevalent, and is now a principal and loathsome feature in the morbidity of these islands. Yaws is practically confined to the tropics and subtropics, and even there is absent at high altitudes.
Etiology. Contagion and heredity.— As yaws is highly contagious, all circumstances favouring contact with the subjects of the disease favour its occurrence. Simple skin contact does not suffice; a breach of surface is necessary. Probably the virus is often conveyed by insect bites, or by insects acting as go-betweens and carrying it from a yaws sore to an ordinary abrasion, wound, or ulcer. Thus the disease often commences in a pre-existing ulcer. Cases are prone to originate in certain dirty houses, the virus from previous yaws patients seemingly impregnating the floors and walls of the filthy huts in which the latter had resided. In this way the disease may be acquired without direct transference from an existing case. ​Yaws is neither hereditary nor congenital. A pregnant mother suffering from yaws does not give birth to a child suffering from the same disease, nor one which will subsequently develop yaws unless the virus be first introduced directly through a breach of surface after birth. It is not conveyed by the milk; nor does a suckling suffering from yaws necessarily infect its nurse.
Age, sex, occupation, race.— Although two-thirds of the cases in the West Indies occur before puberty, no age is exempt. Three males are infected to every female attacked. Occupation has no manifest influence. In the West Indies, Europeans, Chinese, and Indians catch the disease if exposed to the contagium.
The virus.— Both Pierez and Nicholls found a micrococcus in yaws tissue and in the exudation. Cultures of this micro-organism introduced into certain animals did not give rise to the disease
In 1905, by overstaining with Leishman's and Giemsa's stains, Castellani demonstrated in scrapings of yaws tissues the presence of an extremely delicate treponema, Treponema pertenue (Spirochœta pertenuis, S. pallidula), very like the spirocbæte of syphilis. Castellani's observations have been amply confirmed.
To demonstrate the treponema, slides should be prepared from scrapings of an incised yaw papule before it has ruptured. The dried films are then overstained by Giemsa's or Leishman's method. The Burri or indian-ink method (see p. 231) provides a rapid and convenient means of demonstrating the spirochsetes as thin wavy lines on a dark background. They can only be seen in a living state by the dark-ground illumination method. A fully developed yaw is unsuitable, because, in consequence of its having been exposed to external sources of contamination, a variety of organisms will be present and may confuse the observer. Opinions differ with regard to the dimensions, presence or absence of flagella and undulating membrane, and other minute details; suffice it to say that T. pertenue to the ordinary observer is morphologically indistinguishable from the corresponding germ of syphilis. Ranken, using ​dark-ground illumination, has observed the extrusion of minute refractile granules which, after a brief interval, exhibit active rotary movements and which may constitute a stage in the evolution of the parasite. T. pertenue has been found in the spleen, lymphatic glands, and bone marrow, and, doubtless, it occurs in the blood. It is inoculable into monkeys and rabbits; in the former, especially in the orangoutang, it gives rise to lesions similar to those in man.
Cultivation of T. pertenue has been successfully performed by Noguchi in ascitic fluid containing a piece of fresh animal tissue such as the kidney, the whole being covered with a layer of sterile paraffin. This rather complicated technique has been simplified by the later work of Hata, who substituted horse-serum in which the inoculation is made through the upper solidified layer-. The organisms develop anærobically in the lower fluid layers. To succeed in the cultivation of the pathogenic spirochsetes strict anærobiosis is necessary.
Symptoms. The initial fever.— In yaws there is an incubation stage of very variable duration two weeks to six months*— the appearance of the characteristic eruptions being preceded by a certain amount of constitutional disturbance. The intensity of the general symptoms varies within wide limits. Sometimes they are hardly perceptible, and are not complained of; usually there is well-marked malaise with rheumatic pains. Occasionally there is severe constitutional disturbance, lasting for about a week, with rigor, smart fever— 100° to 103° F.— persistent headache, pains— worse at night— in the long bones, joints, and loins, and sometimes gastric disturbance and diarrhœa. During the decline of these constitutional symptoms the eruption appears.
Stage of furfuraceous desquamation.— The skin becomes harsh and dry, loses its natural gloss, and here and there patches of light-coloured, very fine furfuraceous desquamation, best appreciated with the aid of a lens, are formed. These patches are mostly ​small and circular; occasionally they are oval, irregular, or form rings encircling islets of healthy skin. Their extent and number are very uncertain. They are scattered irregularly over limbs and trunk; occasionally they may be almost confluent, the patches coalescing and giving rise to an appearance as if the entire skin had been dusted over with flour. On the other hand, this furfuraceous desquamation may be so slight as to be overlooked. In other instances it may be very marked, the heaping up of desquamating
Fig. 89.—Case of yaws. (Journal of Tropical Medicine.)
epidermic scales producing white marks, very evident on the dark skin of a negro or Oriental.
This patchy, furfuraceous condition of the skin not only occurs at the early stages of yaws, but may persist throughout the attack, or reappear as a fresh eruption at any period of the disease.
The yaw (Figs. 89, 90).—When the furfuraceous patches have been in existence for a few days, minute papules appear in them. Describing these papules, ​Nicholls remarks that, in examining them with a lens, "they are seen to be apparently pushed up from the rete Malpighii through the horny epidermis, which breaks over their summits and splits in radiating lines from the centre, the necrosed segments curling away from the increasing papule. When
Fig. 90.—Another case of yaws.
the papules become about a millimetre in height and breadth, a yellow point may be observed on the summits ... consisting not of a drop of pus under the epidermis ... but of a naked, cheesy-looking substance, which cannot be wiped away unless undue force be used. Frequently a hair will be observed issuing from this yellow substance, thereby indicating that the hair-follicles are the centres of the change ​going on." This papular eruption may persist during the entire attack, or it may appear at any time during the course of the disease. When extensive and occurring late, it indicates a protracted attack.
The papule, having arrived at this stage, may either cease to grow, the apex becoming depressed, cupped, and lined with the yellow cheesy material alluded to; or it may go on, increasing in size, to the formation of the typical yaw. In the latter case the lesion gradually grows into a rounded excrescence, the yellow material at the top widening out so as to form a complete cap encrusting the little tumour. The yaw so formed may be no larger than a split pea; or it may attain the breadth of a crown-piece. The smaller tumours are hemispherical; the larger are more flattened or even depressed at the centre, possessing everted, somewhat overhanging, rounded edges. Occasionally, though rarely, a big yaw may include an area of sound skin. Several yaws may coalesce, and together cover a large and irregular surface, as an entire cheek, a popliteal space, or the dorsum of a foot. In the case of these large yaws, the surface of the growth is apt to be irregular and fissured. The neighbourhood of the mouth and anus are favourite sites for coalescent yaws; in such situations the moisture of the parts softens and removes the crust wholly or in part, so that the surface, in addition to being fissured, may be more or less bare, sodden, and fungoid.
The crust which caps and encloses an uninjured yaw is yellowish, granular, blotched with blood-stains and encrusted dirt. At first the crust is somewhat moist, but gradually it becomes dry, brown, and even black. The crusts are firmly adherent, requiring some force to remove them; a proceeding which, though painless, may entail a little oozing of blood. Deprived of its crust the little swelling is seen to be red in colour, and generally smooth and rounded on the surface. According to size, it stands out any thing from ⅛ to 6/8 in. above the surrounding healthy skin. Immediately after removal of the crust the exposed surface begins to pour out a pale, yellowish​grey, viscid fluid which soon becomes inspissated, rapidly forming a fresh cap to the yaw. Pus, unless as a consequence of irritation, is not, as a rule, found under the crust.
Although the formation of the papules and yaws is attended with much itching, the yaw itself is not at all sensitive; the tumour may be touched, with acid even, without causing pain— a diagnostic point of some importance.
The yaw usually attains its maximum development in two weeks. For several weeks longer it remains stationary before beginning to shrink. The crust then thins, shrinks, darkens, separates at the periphery, and at last falls off, disclosing at the site of the former fungating mass a slightly thickened spot of fairly sound skin which, though pale at first, may subsequently become hyperpigmented.
Ulceration.— Such is the normal process of evolution and involution of a yaw. But it sometimes happens that the tumours, in place of becoming absorbed, break down and ulcerate, the ulceration, however, being confined to the yaw itself. In other instances ulceration goes deeper and extends circumferentially, giving rise to extensive sores with subsequent cicatricial contractions. Such ulcerations may or may not be encrusted. With the development of the deeper and wider forms of ulceration, the typical lesions of yaws may disappear for a time, or perhaps permanently. In the latter case the ulcers are said not to be infective, and do not communicate yaws; they are, therefore, to be regarded rather as complications or, it may be, sequelæ. Such ulcers may persist for years. Ulceration, according to Nicholls, occurs in about 8 per cent, of cases.
Onychia.— Yaws may occur around or under a nail and give rise to a troublesome form of onychia.
Foot yaws.— When a yaw develops on the sole of a foot, in consequence of being bound down by the dense and thick epidermis it causes much suffering. Spreading laterally under the thick, leathery, and unyielding epidermis, it may attain a large size. After a time the epidermis over the growth gives way, ​splitting in a radiating fashion. Pressure being thus removed, the yaw fungates, and suffering diminishes.
A cracked, scaly condition of the hands and feet, sometimes persisting for years, is not unusual in negroes, and must not be confounded with yaws, although not infrequently the two conditions coexist.*
Distribution.— The yaws may be scattered over the whole body; or the crop may be limited to one or two growths; or they may be confined to a circumscribed region of the skin. They are commonest on exposed parts, on the anterior surface of the body, and on parts especially liable to injury, as the feet and legs. They are most frequently found on the lower extremities; rarely on the scalp, and still more rarely in the axillæ. They are hardly ever seen on mucous surfaces unless about the lips, around the angles of the mouth, and in the nostrils, where they often form clusters.
Duration and recurrences.— Yaws lasts for weeks, or months, or years, its duration depending on the general health, idiosyncrasy, hygienic conditions, and the treatment employed. Mild cases in healthy subjects finish in about six weeks. In other instances, especially in the debilitated, the disease runs on for months, successive crops of eruption being evolved. Sometimes these recurrences may stop short at the stage of desquamation, or at the papular stage, or ​they may proceed to the formation of typical yaws. The recurrences are usually preceded by feverishness, pains in the bones and joints; and the successive crops may either be limited and partial in their distribution, or they may be general. In Fiji, Daniels states, the average duration of an attack of yaws is about one year.
The general health.— Except during the initial fever, or during one of the recurring febrile relapses, the general health is not, as a rule, affected. Occasionally, however, there is debility and cachexia; or there may be enlargement and tenderness of the lymphatic glands. In other instances the rheumatic pains are a principal feature, and may be very severe.
Persistent yaws.— That yaws sometimes effects a permanent hold is shown by the persistency with which it occasionally continues to recur during many years. In such cases the lesion has always the characters of a true yaw, and cannot be regarded as a " secondary " or " tertiary " manifestation in the sense in which these terms are applied to the late lesions of syphilis.
Dactylitis.— Powell describes two cases, mother and child, in whom, concurrently, a uniform swelling of the proximal phalanges of both hands occurred during the third year of an attack of yaws. To the touch the bones gave the impression of being rarefied. Such swellings are not uncommon in yaws.
Question of a primary sore.— An interesting point in the symptomatology of yaws is the question of the occurrence of a primary sore, as in syphilis. Numa Rat says there is such a sore, but that it is usually overlooked. He describes it as a papule with a pale yellow material at its apex, which may remain a papule, or which, after seven days, may ulcerate and subsequently cicatrize. Other observers do not agree with this. They say that though yaws virus applied to a pre-existing ulcer may render it unhealthy-looking and cause it to fungate like an ordinary yaw, yet successful puncture inoculations, although they sometimes give rise to a yaw at the point of inoculation, do not by any means always produce a local lesion, ​much less an ulcer. Formerly it was thought that the lower animals were not susceptible to yaws. Several observers, including Castellani, have now shown that monkeys, even of a low order, can be successfully inoculated. Rabbits are also susceptible to intratesticular and subcutaneous inoculations (Nicholls and Castelli).
Sequelæ.— Mention is often made of nodes, of gummatous - like thickenings, and of punched - out, serpiginous and lupoid ulcerations in connection with yaws. Many authorities regard all such phenomena as being generally the results of an independent, though concurrent, syphilitic or tubercular infection.
On the other hand, the peculiar character of the periosteal thickenings; the sabre-like bending of the tibiae as if from some process of rarefying osteitis often leading to spontaneous fracture; the similar distortions of the bones of the forearms; the chronic serpiginous ulcerations of the forearms and legs, which, subsequently cicatrizing, lead to constriction, and cause unsightly chronic œdematous swelling of the distal parts; the gumma-like lumps on arms and legs, and even on the lips; these morbid phenomena, often encountered in yaws countries, taken in conjunction with the nature of the parasitic cause of this disease, tend to the conclusion that these lesions are of the nature of tertiary sequelæ. (Figs. 91, 92.) The subject requires further observation and study.
Gangosa; destructive ulcerous rhino-pharyngitis (Leys).— This disease, which has been regarded by some as a sequel of yaws, generally commences as an ulcer on the soft palate. Slowly spreading, it may make a clean sweep of the hard palate, of the soft parts, cartilages and bones of the nose, sparing the upper lip, which is left as a bridge across a great chasm, the floor of which is formed by the intact tongue. The disease may be arrested spontaneously at any period of its progress and long before so extensive a mutilation as that described has been effected; but it is always a long-standing and chronic affair and may linger as an indolent ulceration for years. As a rule, the larynx is spared; but, although ​phonation may be retained, articulation is seriously impaired.
[Photo: P. H. Bahr.
Fig. 91.—Tertiary yaws, showing sabre-like deformity of tibia, radius and ulna, and multiple cutaneous ulcerations.
This disease is very common in parts of the West Indies—Dominica for example (60 cases in a population of 2,000, Numa Rat), Guam, where it is known as gangosa (1·5 per cent. of the population, Leys), the Carolines, Fiji, British Guiana, and, undoubtedly ​many other parts of the tropics. I believe I have seen the same condition in South China.
It occurs at any age from childhood to 80. Leys saw it in Guam in children of 3, 4 and 9 years respectively.
[Photo: P. H. Bahr.
Fig. 92.—Tertiary yaws, showing tibial periosteal nodes, ulcers, and deformity of phalanges.
The lesion has been attributed to leprosy, tuberculosis, syphilis, and yaws. Against its being a leprous disease is the circumstance that it is not attended with any of the other phenomena of leprosy. ​Against its being of a tuberculous nature is the circumstance that it is confined to the tropics. Against its being syphilis is the practical absence of syphilis among the natives of Fiji, where this form of ulceration is particularly common. Against its being a sequel of yaws is the want of correspondence in the proportional prevalence of the two diseases; for, although ulcerative rhino-pharyngitis is common in some places in which yaws is common, it is rare in other places where yaws is common, and common in other places where yaws is rare. For these and other reasons Leys has thrown out the suggestion that destructive rhino-pharyngitis of the tropics is an independent disease produced by a special micro- organism as yet undetected, and not, as has been supposed, a sequel of yaws. On the other hand, it may be a form of buccal leishmaniasis.
Mortality.— Although in the literature of the subject reference is made to deaths from yaws, yet, judging from the statistics collected by Nicholls, the mortality must be very small indeed. In 7,157 West Indian cases, treated in various yaws hospitals, there were only 185 deaths— a mortality of 25.8 per thousand; a death-rate, as Nicholls points out, less than the average annual death-rate in one of the islands —Antigua. Doubtless, although yaws itself seldom proves directly fatal, intercurrent diseases, such as sloughing phagedæna and phagedænic ulceration, predisposed to by the skin lesions, occasionally do so.
Morbid anatomy and pathology.— No visceral changes have been found peculiar to yaws, although, of course, when yaws concurs with syphilis, gummata, etc., may be found; in this case the concurrent gummata may belong to the syphilitic and not to the yaws infection. An important point of contrast in the respective morbid anatomy of yaws and syphilis is the absence of endarteritis in the former and its frequency in the latter.
The tumours on the skin are granulomata made up of round or spindle-shaped cells, held together by a small amount of connective tissue and abundant blood-vessels. The focus of the circumscribed cell ​proliferation is the papilla, which becomes very much swollen, and the Malpighian layer.
Diagnosis.— A painless, insensitive, larger or smaller, circular, encrusted, red granulomatous excrescence occurring in the endemic district is almost certainly yaws. The most important point in connection with yaws, both as regards diagnosis and etiology, is its relation to syphilis. It has been held by some distinguished authorities— Hutchinson, for example— and is still maintained, that yaws is syphilis modified by race and climate. Certain features which the two diseases have in common are pointed to, and, doubtless, the discovery of a spirochæte in association with both diseases will be adduced in support of this contention. So far as clinical and microscopical evidence goes, it is decidedly in favour of, not to say conclusive for, regarding the two diseases as specifically distinct. There are many points of contrast in their clinical features. I may mention the primary sore, the infection of the foatus, the adenitis, the exanthem, the alopecia, the absence of itching, the iritis, the affection of the permanent teeth, the bone and eye affections, the congenital lesions, the polymorphism of the eruptions, the nerve lesions and the gummata of syphilis. All these are wanting in yaws. Moreover, both diseases may concur in the same individual (Powell cites two cases, and Charlouis two, of syphilis supervening on yaws); and antecedent syphilis certainly does not confer immunity as against yaws, nor antecedent yaws against syphilis. The serum of both diseases gives a positive Wassermann reaction. Monkeys inoculated with yaws are not absolutely immunized against syphilis, but Prowazek found under experimental conditions that inoculation of the spirochæte of yaws conveys a relative immunity to a subsequent syphilitic infection, and that monkeys were less susceptible to syphilis after a previous attack of yaws. Yaws may die out in a community, as in British Guiana (Daniels), yet syphilis remain; yaws may be universal in a community, as in Fiji and Samoa, and yet true syphilis, whether as an acquired or a congenital ​disease, be unknown. Finally, syphilis has never been shown to give rise to yaws, nor yaws to syphilis; neither, so far as known, has yaws been evolved in any community from syphilis, or appeared independently where the possibility of its having been introduced from a recognized yaws centre could be excluded with certainty.
The therapeutic argument for the identity of the two diseases is a very fallacious one. Sulphur will cure scabies and pityriasis versicolor; yet from this circumstance we may not conclude that these diseases are identical. The same may be said in respect of the influence of mercury and iodine on syphilis and on yaws.
Prophylaxis resolves itself into the adoption of measures to prevent contagion. These are: the isolation and segregation of the affected; the dressing and treatment of wounds in the hitherto unaffected; the application of antiseptic ointments to yaws sores, so as to obviate the diffusion of germs; the purifying or destruction by fire of houses or huts notoriously infected; the prevention of pollution of bathing-water by yaws discharges.
Treatment.— All are agreed as to the propriety of endeavouring by good food, tonics, and occasional aperients to improve the general health. Most are agreed as to the propriety of endeavouring to procure a copious eruption by stimulating the functions of the skin by warm demulcent drinks; by a daily warm bath with plenty of soap; and, during the outcoming of the eruption, by such diaphoretics as liquor ammonise acetatis, guaiacum, etc. Confection of sulphur is also recommended as a suitable aperient; it may be taken frequently in the early stages of the disease. All are agreed as to the propriety of avoiding everything— such as chill— tending to repress the eruption; warm clothing is therefore indicated. Many use mercury, or potassium iodide, or both, after the eruption is fully developed. These drugs have undoubtedly the power of causing the eruption in yaws to resolve. Some practitioners rarely use them, or, if they use them, do so only at the latest ​stages of the disease, considering that relapses are more prone to occur after their too early employment. Mercury, owing to its proneness to cause anæmia, is less frequently employed than potassium iodide. Where the eruption is persistently squamous, or papular, arsenic is frequently prescribed. Some touch the yaws with sulphate of copper; some apply nitrate-of-mercury ointment; others, iodoform ointment; others leave them alone, confining their local measures to the enforcement of cleanliness. When the soles of the feet are attacked, the feet ought to be soaked in warm water to soften the epidermis, which should then be cut away sufficiently to liberate the subjacent yaw. Ulceration must be treated on ordinary principles. During convalescence iron, arsenic, and quinine are indicated.
Except where much bone destruction has taken place, salvarsan and, better, neo-salvarsan have a rapid and remarkable curative effect in yaws in every stage of the disease, including "gangosa." They are now the recognized specific treatment, and may be given intravenously or intramuscularly. The dose is 4 to 8 gr. for an adult male, proportionately less for females and children. The reader is referred to p. 243 for a description of the technique of administration. Alston has made the curious and interesting observation that the serum obtained from a blister applied to a yaws patient who has recently been treated with salvarsan acts, when injected subcutaneously into another yaws patient, as effectually as a dose of salvarsan.
The systematic use of salvarsan in a yaws community would, if thoroughly carried out, promptly get rid of the endemic, and, wherever possible, should be enforced.
* ↑ * Paulet, who inoculated 14 healthy persons with yaws, found the first lesion in from twelve to twenty days; Charlouis, in 28 inoculations, observed a papule at the site of inoculation after fourteen days. Naturally acquired yaws is reputed to have a longer incubation period than the inoculated disease.
* ↑ The furfuraceous eruption has been carefully studied by Nicholls. It is not mentioned by the majority of authors.
* ↑ * In the course of time the West Indian negroes have adopted a peculiar jargon— a mixture of French, English, and Spanish—to designate the various manifestations of yaws. The scaly patches are known in some of the islands as "pian dartres," in Jamaica as "yaws cacca"; the papular stage of eruption as "pian gratelle"; when the papular eruption occurs as a late symptom it may be called "pian charaib," or "guinea-corn yaws." The developed yaw is sometimes known as "bouton pian." "Tubboes," "tubba," "crabs," "crappox," "crabes" are expressions applied to the painful manifestations on the soles of the feet. Forms of chronic dermatitis on hands and feet are called "dartres," "tubboe," "crabs," " dry tubboes, " or, where exudation goes on between cracks in soles or palms, "running crab yaws." A large persistent yaw, probably in many instances the seat of the original infection, is sometimes known as the "mother," or "grandmother," or "mamapian"; smaller yaws as "daughter" or "granddaughter" yaws. Yaws which show themselves some time after the disease appears to have subsided are called "memba" (remember) yaws. Yaws coalescing in the form of a ring are called " ringworm " yaws.