Yaws : its nature and treatment an introduction to the study of the disease / by J. Numa Rat.

  • Rat, Joseph Numa.
Date:
1891
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Licence: Public Domain Mark

Credit: Yaws : its nature and treatment an introduction to the study of the disease / by J. Numa Rat. Source: Wellcome Collection.

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    infected is possibly not greater than that of those who have never suffered from the disease. One instance in which Yaws has been contracted a second time is sufficient proof that it can be so contracted. The rarity of the instances only shews that it is a possible event which seldom occurs; but such instances are far from being as rare as they are thought to be. Hirsch writes as follows : “ Wherever Yaws has been observed hitherto, it is especially during childhood (from the 3rd to the 12th year) that it has occurred. But the often expressed opinion that having survived the disease in youth abrogates the predisposition to it for the rest of life, does not hold good absolutely at all events. Bajon and Thomson had already stated that this removal of susceptibility to subsequent attacks was much the same as in small-pox ; that is to say, it was the rule, but there were exceptions. Ferrier also speaks of the same person taking it more than once, and Charlouis says, ‘ I can confidently vouch for the fact that framboesia may attack the same person more than once; and the truth of that may be proved not only by enquiring into the history of cases, but also by inoculation.’ ” Several cases of subsequent attacks have come under my observation of which I have men¬ tioned two at the end of this treatise. It is customary for those who will not allow the possibility of a second attack of Yaws to attribute all second appearances of the disease to a return of the original attack, which they consider to have been uncured. This may be an explanation of such tertiary frambcesial lesions as may appear after secondary or other previously existing tertiary symptoms, but cannot possibly account for the development of characteristic Yaws tubercles (secondary lesions) over the body, years after a first attack. Yaws in the Lower Animals. Fowls are subject to a disease the eruption attending which is similar, both macro- and microscopically, to that of human Yaws. When thus afflicted, the animal becomes anaemic and loses flesh ; and unless carefully attended to, is very liable to succumb to the affection. Though the tubercles may break out over any part of the body, they are most plentiful and conspicuous about the head and beak, the eyes being almost or entirely closed by the scaly eruption. Cattle, also, may be similarly affected, the disease being apparently limited to bulls and cows, for I have never observed it in sheep and goats. It has not been proved, either by my own experiments or by those of other observers, that human Yaws can be conveyed to the lower animals or that of the latter to man ; but there is no difference between the two eruptions, even as regards the discharge from them, which is acid in both. It may be that the same micro-organism which originally produced the disease both in man and the lower animals has in course of time assumed different forms, and has become accustomed to surroundings without which it cannot exist. It is possible that, by cultivation, this organism, in the case of the lower animals (whether bacterial or protozoic), may gradually be made to thrive in human tissue and vice versa. Apart from the increased facility for therapeutical and other scientific investigations which proof of the identity of the disease in man and the lower animals would afford, the interest of experiments with the Yaws virus of man on the lower animals and vice versa lies chiefly in the possibility of obtaining, for inoculation purposes, an attenuated human virus or a virus from the lower animals which would prove against Yaws as prophylactically efficacious as vaccine lymph against variola. ^Etiology. * Climate.—The localities in which Yaws prevails most extensively are damp, hilly and isolated districts in the tropics. Some of the places in which I have known the disease to exist most extensively and in the severest forms are otherwise very healthy as compared with others where it is entirely absent. That condition of climate known as “ malarious ” does not appear to be an essential element in the production of the disease ; though it may be an indirect cause of it by its debilitating influence. Affections similar to Yaws, such as sibbens, mal de chicot, &c., have prevailed for a time in cold climates; but they are not identical with Yaws, and are rather local epidemics of syphilis. Yaws has been observed to spread more rapidly after continued rains. Allowing it a microbic origin, moisture may have a revivifying influence on its genus, which may subsequently rise with the dust during dry weather. Fowls are generally attacked with Yaws about March ; and the popular theory in the West Indies is that the disease is due to their eating the cashew nut. There is no doubt that the consumption of a pungent, substance is liable to produce irritation of the skin and sometimes causes in fowls an eruption like that of Yaws in appearance. By causing hypersemia of the skin it may aggravate the Yaws eruption, or, by the ulcers which it may produce, facilitate the entrance of the virus into the system; but it cannot, by itself, originate Yaws. March is the commencement of the hot weather and the end of the rainy season. The prevalence of Yaws about that time may be explained, as suggested above, by the influence of heat following a long period of rain. Nationality.—No race is exempt from the disease, though the Africans are . the most commonly affected and, next to them, those of mixed African blood. Its comparative rarity among Europeans is due rather to their avoidance of contagion than to racial immunity. It is capable of attacking East Indians and Caribs with as much severity as Africans; while, under favourable circumstances, the latter remain free from the affection. * The prominence given to personal contact as the chief source of contagion in Yaws, has diverted attention from other media through which the disease may he communicated, such as air, soil and water. The idea of contagion from these sources seems to he borne out by the fact that infants, who are too helpless and tender to he left on the hare ground, generally escape the disease, which is commonest among children who are old enough to crawl or run about in mud and dust.