Report of veterinary surgeon J. H. Steel, A. V. D., on his investigation into an obscure and fatal disease among transport mules in British Burma, which he found to be a fever of relapsing type, and probably identical with the disorder first described by Dr. Griffith Evans under the name "Surra", in a report (herewith reprinted) published by the Punjab Government, Military Department, No. 439-4467, of 3rd. December 1880-vide the Veterinary Journal (London), 1881-1882 / [By Steel, J. H.].

Steel, John Henry

Date:: 1886

Credit: Report of veterinary surgeon J. H. Steel, A. V. D., on his investigation into an obscure and fatal disease among transport mules in British Burma, which he found to be a fever of relapsing type, and probably identical with the disorder first described by Dr. Griffith Evans under the name "Surra", in a report (herewith reprinted) published by the Punjab Government, Military Department, No. 439-4467, of 3rd. December 1880-vide the Veterinary Journal (London), 1881-1882 / [By Steel, J. H.]. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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perhaps as free motile nuclei, such as are noticeable in the majority of specimens and distinguishable from the free nuclei of healthy blood only by a sort of purpose in their movements, but more probably as in a quiescent form so that they are detectable only on aniline staining.* Whether naturally the organism enters the system in the spirilloid forms, or as a mic-rococcus, or as an unrecognizable germ, we cannot say, and we are equally without guiding evidence as to whether its entry is effected by exercise of its eel-like activity or by its use of a special boring organ too minute for detection with ordinary microscopical powers. The size of spirilloids is not sufficiently great to exclude the possibility of their passing through the walls of normal capillaries, as do the leucocytes, but the passage may be to an extent forced, for we have evidence that the blunt extremity or head must be armed with some mechanism, if only a sucker, to enable it to obtain a grip on the red corpuscle; the disintegration of the latter would lead us to infer that the arrangement is something more formidable than a sucker. We know that the parasites, small though they be, can exercise a great deal of strength at the expense of the corpuscles. The amount of force expended is often greater than that which is exerted in adhesion between two corpuscles in a rouleau ; it is sufficient to enable the parasites to drag the corpuscles about, shake them, distort them into various shapes, and it suffices to enable one parasite to drag two corpuscles about with ease and rapidity, also to shake a long rouleau, but not to detach it from the mesh- work to which it belongs. This strength is ordinarily exercised in locomotion, in traction, in changes of form, and in pushing a way among the corpuscles. The energy, strength, and perseverance shown by the parasites in making their way through an aggregated mass of red corpuscles should more than suffice to procure them an entry into living capillaries. The parasites in their spirilloid form, much more so in their possible germ phase of development, would find no difficulty, under the ordinary life conditions of mules, in obtaining access to the mucous membranes of the alimentary and respiratory systems ; entry via the skin is not impossible especially in the presence of open wounds, blistered surfaces, &c., but we have evidence against its ordinary occurrence. The air, water, and food must therefore be looked on with suspicion as vehicles for conveyance of the organism which generates relapsing fever into the system of the victim. ] 5. But not only is it necessary that the organism shall gain access to the system, it is also essential that the individual invaded be susceptible to attack in order that the parasite may obtain a fair footing from which to extend its ravages. My inoculations of the bullock have thus far been valuable, in that they have shown that local irritant action by the parasite need not necessarily be followed by systemic infection. That the opposite is not the case is shown by my inoculation of the pony in which both local and general symptoms were the result. In many diseases individual peculiarities have a marked effect on the taking or rejection of the specific virus, but in equine patients my administrations of relapsing fever parasites have been invariably followed by success in communication of the disease. Animals in fat condition have succumbed as rapidly (perhaps more so) as the weak and emaciated ; old and young, male and female, horse and mule, have become affected. Thus in this disease, as in anthrax, but to a less degree, predisposing causes sink into insignificance from a practical point of view in comparison with the determining inl3uences, viz., those which have a direct influence in conveyance of the pathogenic organisms into the system, for we can alter the latter, but the former are beyond our control to a great degree, or, however much we may modify them, we cannot render the system absolutely insusceptible to invasion by any means we are yet acquainted with. Yet we cannot altogether afford to ignore predispositions on the part of the animal, and so shall have something to say about age, color, breed, and conformation after we have drawn attention to a few other matters to be taken into consideration in studying the causes of disorder. It is evident that the same cause operating on different individuals does not necessarily produce the same effect. Thus many animals exposed to a specific influence may resist it, whereas others succumb. Therefore we must not argue that, because a supposed cause is not in every case followed by an attack, it is not a true cause, nor must we, on the other hand, consider that, because a supposed cause fails to generate disease, the animal is * In his report on Surra Dr. Evans says :— The blood parasites do not disappear from the blood absolutely when it becomes difficult to find one in a drop of blood ; when one brood or generation dies there are ova or spores left for the development of another brood,''

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