Portal:Royal Society of Tropical Medicine and Hygiene

“ The amount of injury done by the immature parasite in its travels towards its permanent abode is so trifling that no serious disease can possibly result from it. The mature animal itself lies extended in a vessel, and is perfectly adapted by its size and shape for the situation which it occupies; it creates no irritation, and the small amount of obstruction which it may give rise to is readily compensated for by a rich anastomosis. The embryos move along with the lymph, and, being no broader than the corpuscles, readily pass the glands and enter the general circulation. ”

“ As with the growth of a child, we hardly appreciate the recent progress of tropical medicine, living with it, so to speak, as we do from day to day; but if we come from abroad after an absence of years, or if we compare the state of knowledge, say, of twenty years ago with that of to-day, we shall find that the stripling has not only altered in feature, but has grown into a veritable giant. ”

“ But when I come to examine the distribution of the lymphatics in the different situations in which elephantiasis occurs, I find a difficulty, from a mechanical point of view alone, of explaining how the obstruction which is necessary to produce a complete lymph stasis can occur. Looking again at the illustration of the superficial lymphatics of the leg, at what point in the limb can a single worm be situated so that the lymph-stream would carry the ova so as to obstruct the whole of the superficial inguinal glands? ”

“ The study of the arthropod blood-suckers and the correlated diseases has grown to be so vast a subject that for its proper appreciation special studies have to be made and its teaching relegated to special men. In Davidson's day a single culex was all that we had to bother ourselves about; but nowadays we have to know something about some 600 species of mosquitoes; and so in a less degree with ticks, tsetse flies, and several other though less important blood-suckers. Truly the burden of the student of tropical medicine has become a heavy one. ”

“ That was the relationship of Oriental sore to the deadly disease kala-azar. Per se, Oriental sore did not endanger life; though protracted, the tendency was to cure, and we could inoculate it without apprehension of serious evil. Kala-azar, on the contrary, never healed; it was most invariably fatal; and it would be, therefore, entirely unjustifiable to inoculate kala-azar into any human being. Yet the parasite of Oriental sore and the parasite of kala-azar were, so far as could be seen with the microscope, identical. ”

“ It is apparent to any one who has followed the discoveries of recent years that tropical medicine, more than any other branch of medicine, is dependent on several of the collateral sciences, more especially on the various branches of natural history. Our basis therefore has to be a broad one, and in drawing up the constitution of the Society this point has been kept steadily in view. ”

“ He believed that occasionally a reliable culture was obtained, but one could hardly expect, under ordinary circumstances at all events, to get a pure culture from a skin scale. If scales from Tinea imhricata were put in a sterilised bottle and kept for a week, they became covered by an extraneous growth, showing that the skin was contaminated by some additional fungus to that which caused the disease. The only way of preserving, without actually destroying, the fungus of Tinea imbricata was to dry the scales, place them in a bottle also carefully dried, and then to hermetically seal it. ”

“ We now know that the sleeping sickness is a terminal phase of a trypanosome infection—a type of disease hitherto unrecognised in human pathology—that the immediate cause of the sleeping symptom is an infiltration of the lymphatic spaces of the brain with certain small mononuclear cells, that the disease is conveyed by the tsetse fly, and that it is amenable to some extent to arsenic, mercury, and certain dyes—all absolutely recent discovery. ”

“ And in the Tropics, where all forms of microbic life flourish so luxuriantly, where people go about bare-footed and bare-legged, where abrasions and injuries of exposed parts are of daily occurrence, where there is a frequent lack of cleanliness, surely there is ample opportunity for the entrance of pathogenic organisms and resulting attacks of lymphangitis, thickening of the lymph channels, and eventual obstruction. Would a peripheral lymphangitis of the scrotum not account sufficiently for a localized symmetrical elephantiasis with healthy skin uniting it to the body? ”

“ He showed, as you all know, that two species of amoebae are parasitic in the human colon, which, though similar in appearance, differ widely in their life-cycles, in their reproduction, and in their pathogenicity. The research was productive of results which are now among the most familiar facts in tropical medicine, and it is unnecessary to say more than that, while carrying it out, Schaudinn did not hesitate to repeatedly infect himself by swallowing the developmental cysts both of Entamoeba coli and of Entamoeba histolytica, and that he had, in consequence, two serious attacks of dysentery. ”

“ How important it is for the subject itself, as well as for those who are engaged in its study, that the latter should have opportunities, such as this Society is calculated to afford, of placing themselves abreast of the times will be readily understood when we think of the rapid progress that tropical medicine has made within the last few years. This progress has been as remarkable as it has been great; indeed, it is hard to keep pace with it. No sooner have we settled down to digest some new and important discovery than a fresh and perhaps more startling one is offered us ”

“ Craw-craw is, in my opinion, a very slipshod diagnosis to make; it is not a specific disease at all, but a term loosely applied by the natives of the West Coast of Africa to almost any form of skin eruption, including itch, ringworm, eczema, etc., aggravated as these are by dirt and the excessive action of the skin, and it can in all cases be classified among one or other of the well-known forms of skin disease. ”

“ In a science which moved so fast as tropical medicine it was wholesome to have a periodical stocktaking of our knowledge on any given subject, and when one advanced a theory which ran contrary to generally-accepted ideas the review was all the more likely to be of a vigorous and radical character. ”

“ In a number of cases of elephantiasis an examination of the blood shows the absence of filarial embryos, and it is explained that this is due to the blocking of the lymphatics, the embryos being unable to gain the main lymph stream and thus enter the blood; while the presence of embryos in some cases is got over by suggesting that they are derived from a reinfection. In the first place, this assumes an absolutely impervious obstruction, for, of course, as the embryos can pass through the smallest blood capillaries, they can do so through the smallest lymph capillaries. ”

“ We should be able to remove the parasite and grow it outside the human body. 3. We should be able to re-introduce it into the human body or that of some lower animal and there reproduce a similar disease. 4. We should be again able to demonstrate the presence of the parasite. With reference to the first, I shall show presently the invariable association of F. nocturna has not being clearly proved; indeed, its absence in the case of elephantiasis is cited as one of the proofs of its association with the disease, and this difficulty requires explanation. ”

“ An important one is to bring together the men who are interesting themselves in tropical medicine, with the idea that by so doing the subject itself will be advanced and we ourselves benefited. With a view to securing these objects, the Society has been placed on a basis as broad as possible. Although domiciled in the Metropolis, it is open to any member of the profession, whether domiciled in London, Great Britain and Ireland, or abroad, and also to those followers of any science or profession capable of forwarding, directly or indirectly, the interests of tropical medicine. ”

“ Everyone knows that the mosquito is the sole vector of malaria, and an enormous literature has grown up around a discovery which has changed radically our views, not only as regards the etiology and prophylaxis of malaria, but has given a powerful stimulus to the study of the protozoa in gal, and also the role of insects in the transmission of disease germs. ”

“ Not only has recent discovery widened our horizon, but many additional workers are now in the field, and hitherto untrodden departments of natural science having a bearing on tropical pathology have been opened by the tropical pathologist. The multiplication of workers is extraordinary, and doubtless is accounted for by the establishment of the several tropical schools in Great Britain and else-where; not least by the sympathy and active encouragement that research in tropical pathology has received at the hands of the British Government. ”

“ Patients who suffer very severely from dhobie itch may get almost well in a few days without any treatment on going to the hills; in coming back to the plains the pruritis and all the other symptoms reappear. The affection has been known to last for many years. It is to be noted that after a time the eruption may spread to other parts of the body—the abdomen, the trunk, legs, etc.—and may develop in rings or may form solid elevated dark red patches. In such situations the disease may be clinically indistinguishable from ordinary T. circinata. ”

“ A lady missionary from Delhi whom he had recently seen developed Oriental sore in the South of France, five months after she had left the place of infection, and that circumstance, viewed in connection with immunity, was an interesting and important feature. Still another point of interest was that the disease occurred almost invariably on exposed parts of the body—on parts that were not generally covered by clothes—and that would lead to the inference that infection took place by some animal which could readily attack exposed parts. ”

“ He thought, however, there were cases when the lesions of dhobie itch were not preceded by any marked inflammatory symptoms. Dr. Brown had also very justly called attention to the fact that in the Tropics medical men were apt to label every skin disease affecting the scrotum dhobie itch, and he certainly agreed with him that the use of chrysarobin ointment or strong goa powder should be restricted to cases where the diagnosis had been proved microscopically. Chrysarobin and Goa powder had a powerful destructive action on the fungus, but he had also seen very bad effects from their absorption. ”

“ While employed in a naval hospital at home, and dealing with diseases from foreign stations, occasionally it is one's fortune to meet with some of the more obscure cases of irregular fever and cachexia, the etiology of which is unknown, or only partially known. Of the latter, the disease called kala-azar, Dum-Dura fever, etc., is of peculiar interest, especially when attacking Europeans, or when it has been possible to demonstrate the parasitic organism. That the disease is more common than is usually supposed is very likely. ”

“ In laboratory experiments we have frequently noticed that even after the treatment had been stopped for a week toxic effects appeared, and this could only be due to the fact that atoxyl had accumulated in the body, and the arsenic had been slowly broken up. We would like to refer to one experiment. A rat was treated about nine months ago with atoxyl and is still showing toxic effects.
We think it necessary to point out that the administration of atoxyl should be given a very careful trial, but that extremely high doses should be avoided as much as possible. ”

“ Although he had tried various methods he had never succeeded in growing the fungus. He was therefore somewhat surprised at the results of Tribondeau and others, who had not only grown it but had reproduced the disease in man by means of cultures. Mr. Cantlie had given a vivid description of a very interesting tropical affection of the foot. He did not think that similar cases were seen in Ceylon, but instances of a peculiar eczematous dermatitis, characterised by terrible itching, and by the formation of large blebs and deep fissures on the feet and toes, were not uncommon. ”

“ I think I have shown how very difficult it is to understand how such a complete obstruction as is required can take place.
Then we must remember that in a population which is infected to a greater or less degree by F. nocturna, any disease, whether it be pneumonia or Bright's disease, or eczema or elephantiasis, ought to show an amount of filarial infection equivalent to the general infection of the population. ”

“ The eczema is generally of the moist variety—the moist surface, the absence of the festooned elevated margin, etc., easily distinguishing it from Tinea cruris. As already stated, however, an eczematous-like dermatitis due to scratching often develops after a time on old dhobie itch lesions.
Prognosis.—The affection, if not energetically treated, has a tendency to become very chronic, and to last for years. Occasionally the eruption spreads to the whole body, forming rings or solid patches : at other times a distressing dermatitis develops on old dhobie itch patches, due to scratching. ”

“ We now come to the third suggestion, which is that elephantiasis is due to the adult female aborting, from injury or otherwise, to the discharge of the immature ova into the lymph-stream, to their impaction in the vessels leading to the lymph glands, and to the complete obstruction, with its resulting lymph stasis, which ensues. In addition to this, it is maintained that lymph stasis alone does not produce elephantiasis—some injury in the area of lymphatic construction must take place ”