Fig. 22.—Section of the heart of a calf infested by cestode larvæ. After Mosler.
Fragmentary as the above data are, they serve to show that we have hitherto been too hasty in concluding that beef and veal measles reside only in the voluntary and striated muscles of their hosts. The facts here recorded prove that the liver of a calf may be extensively invaded by cysticerci, and yet the animal will exhibit no sign of constitutional disturbance. The cestode tuberculosis may come and go without any diagnostic symptom, whilst a few months suffice for the natural death and decay of the parasite by calcareous degeneration. Thus it becomes extremely probable that many experiments hitherto regarded as negative in their results have really been positive; the pathological evidences having been either misinterpreted or altogether overlooked. Every pathologist is familiar with gritty particles in the various viscera of man and animals, but few are probably aware how constantly these are dead and degenerated Cysticerci. The gritty particle itself may be reduced to the merest point, no larger than the receptaculum capitis of the Cysticercus itself, and in course of time it will disappear entirely. Practically it is satisfactory to have experimental evidence of the fact that cattle, as well as other animals, however extensively measled they may have been, can become thoroughly cleansed of the disorder by nature herself. It is only necessary that the diseased animals be separated from infectious influences.
Although the beef measle has never yet been found in man, I have for convenience sake introduced the facts of larval parasitism in this place. The sanitary bearings of this subject are far too important to be dismissed in a summary manner. I have shown that the prevalence or rarity of the beef tapeworm in man is strictly dependent upon the habits of the people; this same cause operating to produce healthy or diseased meat-food, according to the degree of civilisation. In this connection the oft-quoted statements of Kaschin respecting the prevalence of tapeworms among the Burätes, and the well-known frequency of this entozoon in Abyssinia, need only be alluded to.
When discussing the food question in my ‘Manual,’ I freely availed myself of facts privately communicated by Dr Joseph Fleming, and I especially referred to the published labours of Lewis, Hewlett, Veale, and other observers stationed in India. Beef measles are extremely common in the cattle of the north-west provinces of India, so much so that severe restrictions have been imposed upon the consumption of ration beef. The presence of a few measles in the flesh of cattle has been deemed a sufficient excuse for condemning and burying entire carcases. The measle is easily distinguished from that of mutton and pork by the fact that its head is not furnished with hooks, whilst in the place of a rostellum there is a small, centrally placed, retractile disk, which assumes the appearance of a supplementary sucker as in the adult worm. The four true suckers are also comparatively large. The measle usually varies in size from the fourth to the half of an inch in length, but my cabinet contains a specimen nearly an inch long. This was contributed by Dr J. Fleming, who mentions having seen a measle which, when unrolled, measured nearly an inch and a half in length. Although thousands of these bladder worms must exist in the cattle of England, up to the present time not a single instance has been recorded of the occurrence of these cystic parasites in the United Kingdom, except in our experimental animals. Notwithstanding my inquiries, I have not yet found a butcher, flesher, meat-inspector, or veterinarian, who has encountered this parasite in any animal slaughtered for the market. Several butchers have denied their occurrence in meat sold by themselves. Even so late as June, 1874, the presence of measles in the flesh of cattle was denied before an assembly of French savans; yet for many years past I have constantly exhibited measly beef and veal in the lecture room of the Royal Veterinary College. (See the discussion of the Société de Thérapeutique, recorded in the ‘Bullétin Gén. de Thér.’ for June 30th, 1874, and also the ‘Jour. de Thér.,’ No. 14, for July, p. 556, where, however, special remarks on this head have been omitted; see also the ‘Lond. Med. Record’ for July 29th, 1874, p. 472, and the ‘Lancet’ for Dec., 1874, p. 794.) Quite in contrast with the statements referred to are those of recent Italian observers.
Some few years back Professor G. Pellizzari communicated to the Medico-Physical Academy, at Florence, the results of a series of experiments conducted by himself, with the assistance of Dr Tommasi, in regard to the temperature necessary for the destruction of cysticerci in measled meat. An account of these experiments is published in Tommasi’s edition of my ‘Manual.’ The researches were made in relation to certain sanitary measures effected by the Municipal Commission of Florence, the express object of these measures being to prevent the injurious distribution of measly meat, especially that of swine. Signor Bosi, the superintendent of the public slaughterhouses, granted every facility in his power. In a previously published memoir by Professor E. Perroncito it was stated that measly meat (panicatura degli animali) required a higher temperature than that of boiling point for the destruction of the bladder worms in question. In this opinion Signor Bosi shared. According to the original memoir of Perroncito we are told that “about twenty specimens of Cysticerci were collected by the author, and placed in boiling water. After twenty minutes’ boiling, not one of the parasites appeared to suffer. The head continued to be drawn into the body, and when the Cysticerci had their heads drawn out one by one they still appeared to possess all the elasticity of living bladder worms, displaying those movements of extension which are proper to parasites not yet dead. The hooks were observed regularly disposed on the proboscis, where they formed a double crown, the suckers remaining intact.” Perroncito remarked, however, that the Cysticerci showed a coloring tendency towards brown, and he added that “with the aid of two needles it became easy to lacerate the body of the Cysticercus, which appeared to be swollen, and possessed of diminished cohesion of its parts.” It was evident to all eyes, observed Professor Pellizzari, that these statements involved clear contradictions. Yet again, at page 28 of the memoir, Professor Perroncito wrote:—“During the past winter I introduced some little slices (fettuccie) of muscle-flesh (8 to 10 millimètres in thickness), infested with Cysticerci into a vessel (cassolina) containing fat at the temperature of 190 to 200° Cent. (374 to 400° Fahr.). At the expiration of ten or fifteen minutes the slices of meat were fried, and the Cysticerci lying at the surface had acquired a light brownish colour, as if they were roasted. By breaking up the slices one could still see the small reddish muscular bundles, whilst the Cysticerci in the middle remained entire and well preserved. Their heads displayed the hooks and suckers regularly distributed.” It is certainly singular, as Pellizzari observes, that these Cysticerci, having been thoroughly fried and roasted, should still remain alive and in their normal state; but the ultimate conclusion at which Perroncito arrived was still more startling, and one which, if it were true, would not fail to create a considerable stir among our officers of health. On reviewing the whole matter Perroncito says:—“It appears to me that the melted fat alone of hogs (maiali grandinosi) should be utilised, and I am pleased to reckon the illustrious Gerlach and all other distinguished practitioners to be of the same opinion. Permit me, therefore, being well satisfied also with the results of many other experiments, once more to advance the conclusion that, if it is not certain that the Cysticerci die at from 80 to 100° Centigrade (176 to 212° Fahr.), we are quite sure that they dry up and become completely mummified at 125, 130, and 150° Cent. (257, 268, and 302° Fahr.), temperatures which we could easily produce by means of a properly constructed apparatus.”
After remarking upon the serious nature of the conclusion which Perroncito sought to establish, Professor Pellizzari makes further use of quotations which bear upon the question as to whether the quality of the vessels in which the fat of diseased hogs is melted down may not largely affect the degree of high temperature sought to be obtained (in view of a perfect destruction of the Cysticerci). Perroncito repeatedly witnessed the operations of pork-butchers; and when portions of meat were introduced, with water, into the cauldrons, he always saw that the temperature “was maintained between 97° and 98° Centigrade.” However, this part of the question may be dismissed in a very few words, since Perroncito himself finally allows that “the different composition of the vessels cannot elevate the temperature of the fat by many degrees.”
With the praiseworthy intention of either verifying or refuting these conclusions, Pellizzari, with the approval of Bosi and with the assistance of Tommasi, instituted a fresh series of experiments at a private laboratory. The details of these experiments are exceedingly interesting; but as their record occupies several pages of Tommasi’s appendix already referred to, I must content myself with a general statement of the results obtained. Professor Pellizzari found that Cysticerci, so far from requiring a temperature of upwards of 100° Centigrade for their destruction, die at a temperature of 60° Centigrade (140° Fahr.). He had, it appears, previously taken the initiative in recommending certain measures to the Florentine municipality, in view of protecting the public health, and he had now the satisfaction of more than confirming the wisdom of these sanitary precautions. In excessively measled animals the fat is removed and boiled in suitable cauldrons, and has potash mixed with it to render it useful for industrial purposes. By the various measures adopted the entire animal is utilised, and with proper precaution there seems little chance for the measles to arrive at the tænioid or sexually mature condition.
In the next part of his communication Pellizzari touches upon the question of measles in beef, referring especially to the experimental labours of Leuckart and myself. Finding additional support from our views Pellizzari declared the propositions of Dr Perroncito as of no value whatever. “But how is it,” he adds, “that notwithstanding that so low a temperature suffices to kill these cysticerci, yet cases of Tænia are continually occurring?” The answer to this question will appear in the sequel; but meanwhile it will be as well to refer to the recent brochure by Dr Giacomini. This author appears to have had no opportunity of perusing Pellizzari’s communication already cited, and consequently it is not surprising that he should, in common with others, have accepted the original conclusions of Perroncito. Dr Giacomini clearly perceives that, whatever precautions of a hygienic character are suitable for the prevention of disease arising out of the consumption of measly pork, the same, or at all events similar, measures ought to be adopted with the view of checking tapeworm affections arising from the ingestion of other kinds of meat, especially veal and beef. Like Pellizzari, he is satisfied as to the human origin of the small bladder worms found in cattle, and establishes this position not only from the oft-quoted experiments of Leuckart and Mosler, but also from those conducted by myself and Simonds in England, and by Professor F. Saint-Cyr in France. From a careful review and consideration of all the facts of the case, he recommended a more complete supervision over the flesh of oxen before it is employed commercially, and greater precaution when employing veal as food, by causing it to be subjected to a high temperature, in order that the parasites may be killed before it is ingested. It is evident that Giacomini thinks that a temperature exceeding that of boiling-point is necessary for the destruction of the beef and veal measles, since he immediately adds, “Though experiments have not been made with the object of ascertaining the amount of resistance of heat which the unarmed cysticercus can bear, yet, judging by those conducted by Professor Perroncito on the measle of the hog, we are in a position to say that a temperature of 135° Cent. (275° Fahr.) is necessary for the destruction of an isolated Cysticercus, whilst the heat should be raised from 150° to 200° Cent. (302° to 392° Fahr.) for ten or fifteen minutes, in order to ensure the complete destruction of the Cysticerci encapsuled in the interior of a piece of meat.” I have abridged this portion of Giacomini’s text, because his statements are pretty much the same as those already quoted from Perroncito (as cited by Tommasi). But, in the next place, Dr Giacomini is in error when he states that experiments had not been performed on the Cysticerci of the ox. So far from this being the case, similar experiments had long previously been conducted by Dr Lewis in India; and these researches had quite as much to do with the measles or Cysticerci of beef as they had with those of the hog, if not more. Naturally but few foreign investigators can have had access to the work in which Lewis’s experiments were originally recorded, and to which, therefore, I must call their attention. Thus, Dr Tommasi has fallen into the error of supposing that the investigations of Lewis were made in England. It is of very little moment where the experiments were carried on, but Tommasi’s statement (appendix, loc. cit., p. 161), wherein he says that Pellizzari’s experiments, in which he himself took part (ai quali io stesso ho assistito), are even more complete than those made in England by Dr Lewis, and in Germany by Dr Küchenmeister, cannot be allowed to pass unchallenged. If Tommasi had enjoyed the opportunity of consulting Lewis’s original memoir, he would not have underestimated our countryman’s labors. The memoir by Lewis is singularly complete, and well-nigh exhausts all the facts that can have any interest in relation to the question of public health. Towards the close of his essay he expressly states, as the result of investigation—“(1) That exposure to a temperature of 120° Fahr. for five minutes will not destroy life in Cysticerci, but that they may continue to manifest indications of life for at least two or three days after such exposure; (2) that exposure to a temperature of 125° Fahr. for five minutes does not kill them; but (3) after being subjected to a temperature of 130° Fahr. for five minutes, they may be considered to have perished. After exposure to this and higher temperatures, in no instance have I been able (he adds) to satisfy myself that the slightest movements took place in their substance when examined even under a high power. At least, it may be confidently asserted that, after exposure for five minutes to a temperature of 135° to 140° Fahr., life in these parasites may be considered as absolutely extinct” (p. 139). Thus the statements of Lewis and Pellizzari were in perfect accord; and seeing that their conclusions were alike the result of very careful and independent inquiry, it seemed as if the question at issue was finally solved. These investigations made it perfectly clear that Cysticerci of all kinds, whether found in veal, beef, or pork, could not retain their vitality when exposed to a temperature of 60° Centigrade, or, in other words, 140° Fahr.
The rather severe strictures made on Perroncito’s earlier experiments induced the Turin professor to go over the subject more carefully, when he obtained excellent results. He finally ascertained that Cysticerci perished at a temperature below 50° C. (122° Fahr.). In May, 1877, Dr Perroncito furnished me with an account of his researches. With the exception of a few verbal alterations, for which I am responsible, Perroncito wrote as follows: