The notion that particular breeds of swine are more liable to be infested than others is absurd, since infection must be due to the facilities offered for swallowing garbage, especially dead rats. According to Drs Belfield and Atwood 8 per cent. of slaughtered American swine contain Trichinæ. In infested hogs they found from 35 to 13,000 parasites in a cubic inch of muscle, and by repeated feedings they succeeded in rearing about 100,000 Trichinæ in the body of a rat.
In regard to the disease in man let us glance at the phenomena that presented themselves in Plauen, a town of Central Saxony. Drs Böhler and Königsdörffer, who first saw this disease and treated it, state, according to Leuckart, that “the affection began with a sense of prostration, attended with extreme painfulness of the limbs, and, after these symptoms had lasted several days, an enormous swelling of the face very suddenly supervened. The pain occasioned by this swelling and the fever troubled the patients night and day. In serious cases the patients could not voluntarily extend their limbs, nor at any time without pain. They lay mostly with their arms and legs half bent—heavily, as it were, and almost motionless, like a log. Afterwards, in the more serious cases, during the second and third week, an extremely painful and general swelling of the body took place; yet, although the fifth part of all the patients were numbered amongst the serious cases, only one died.”
Satisfactory as it may be to note the numerous recoveries which take place, this circumstance is very much marred by the fact that a large proportion of the patients suffer the most excruciating agony. In the main it will be observed that Böhler’s and Königsdörffer’s experience, as recorded by Leuckart, corresponds very closely with that given by other observers. The symptoms, moreover, are very similar to those produced in the original case published by Zenker. In this case, which occurred in the Dresden Hospital (1860), the patient was a servant girl, aged twenty, and the principal symptoms were loss of appetite, prostration, violent pains, contraction of the limbs, and finally œdema, which, in association, perhaps, with a certain amount of pneumonia, terminated her career within a period of thirty days. The post-mortem appearances showed that the larval Trichinæ were the cause of death. The intestinal canal contained numerous sexually-mature worms.
The effects produced by Trichinæ on animals are similar to those occasioned in man. The phenomena were summarised by Davaine (in the journals quoted below) in 1863 as follows:
“The first phase is characterised by intestinal disorder, produced by the development of the larvæ in large numbers, and their adhesion to the mucous membrane of the intestine. In this stage M. Davaine has seen rabbits die with intense diarrhœa; one of two cats which he fed with trichinised meat had diarrhœa for at least a fortnight, but survived. Of five or six rats fed on a similar diet, one only, which was pregnant, died of diarrhœa, after abortion, on the eighth day. According to M. Leuckart, the passage of the embryos of Trichinæ through the intestinal walls sometimes produces peritonitis. This intestinal phase often becomes blended with the next; it may be relieved by the expulsion of the worms by means of the diarrhœa, or may cease with the natural death of the worms.
“The second stage presents general symptoms—muscular pains, &c. These phenomena are dependent on the introduction of the Trichinæ into the muscles; they rapidly acquire their maximum intensity, and have not a long duration. The appearance and duration of this stage are in complete relation with the development and length of sojourn of the Trichinæ in the intestines; in fact, in this entozoon, oviposition is not slow and of long duration, as in many nematoid worms; the genital tube is rapidly formed, and the ova, in its whole length, are developed almost simultaneously, so that the embryos, arriving soon at maturity, are at once thrown out in large numbers into the intestine, and the mother Trichina dies exhausted. If it be remembered that the embryos do not escape before the eighth day, that a certain number of days are required for their arrival in the muscles, and that new ones are not produced after six or seven weeks, it will be understood that the first symptoms of this stage can scarcely appear until the end of a fortnight after ingestion of the diseased food, that they must continue four or five weeks, and that after this they may disappear. This course of events is observed in animals; and in man the symptoms of this stage have shown themselves and become aggravated from the third to the sixth week after infection. Most animals die during this stage; rabbits rarely survive; rats, on the contrary, generally resist it.
“If the animals do not die of the general symptoms or local disturbances proper to these two stages, the inflammatory symptoms cease, respiration becomes natural, and order is re-established. But, in some cases, the number of cysts formed in the muscles are sufficiently great to impede them in the proper exercise of their functions, and hence arises general debility, a kind of consumption which persists or becomes aggravated, and the animal dies of marasmus. M. Davaine has noticed this in rabbits, but especially in a rat.
“Recovery from these phases of trichinal infection may be apparently perfect. A rabbit which M. Davaine kept during five months became large and fat, although it had a large number of Trichinæ in its muscles; a rat which had had these entozoa in considerable numbers during six months was, to all appearance, in good health. Hence he concludes that the Trichinæ produce symptoms only when they are in the intestinal canal, and when they are entering the muscles. Having become lodged in their cysts among the muscular fibres, they may remain harmless for an indefinite time. In every case except one, down to 1859, Trichinæ have been found in the bodies of persons who have died of disease (generally chronic) or by accident; or in the dissecting-room, in bodies regarding which the previous history could not be obtained. In most cases the cysts contained a cretaceous or fatty deposit, showing that they had probably existed several years.
“The observations which have been made on the human subject, in regard to the symptoms caused by Trichinæ, show that they belong, as in animals, to the initial period of infection. They consist in intestinal and in muscular lesions; the latter coincide with the entrance of the parasite into the muscles, and are truly traumatic. In Zenker’s case the intestinal symptoms were swelling and pain; in a case described by Friedreich diarrhœa was present. In all cases the most remarkable symptoms were violent rheumatoid pains in the muscles, not in the joints, which were considerably aggravated by attempts to extend the half-bent limbs. The other symptoms have been variable, but have had a strong resemblance to those of typhoid fever. In several cases there has been abundant sweating; and in one there was a very remarkable miliary and furuncular eruption. The animal heat was diminished in Friedreich’s case; and in those observed in Voigtland by Freytag the temperature never exceeded 102° Fahr.