When we reflect on the facts here related, we can have little difficulty in forming an opinion of the pathology of jaundice occurring in an epidemic form. Its mechanism seems to be precisely similar to that of the isolated cases of the disease which are every now and then met with as the result of blood-poisoning. I have recently seen a case of well-marked jaundice supervene on an attack of scarlet fever, and as it affords a tolerably good illustration of the pathology of such cases, it may, perhaps, be briefly given with advantage.
A London cabman, aged 23, was admitted under my care into University College Hospital, on the 2nd March of the present year. He stated that he had always enjoyed good health, but that lately he had been much out of spirits, in consequence of the death of one of his relatives. On the 25th February, after three days' illness, a scarlatinal rash appeared all over his chest, and extremities, and four days later (the day before his admission), he became jaundiced. March 3rd. His skin is now of a bright yellow colour, and when the finger is rapidly drawn across it, a pink line immediately takes the place of the yellowness, showing that there is still great subcutaneous vascularity. The throat is sore, and there is considerable difficulty in swallowing. The conjunctivæ are intensely yellow—proportionally more so than the skin, in consequence of the scarlatinal hue being still blended with the tint of the latter. The urine is high coloured, has a slight deposit of urates; contains a large amount of bile pigment, but no bile-acids. The stools have not been observed to be clay-coloured. The liver is enlarged (dulness extends 5½ inches in a perpendicular direction), and tender on pressure. He complains of pain in the hepatic region on taking a deep inspiration, and of a general uneasiness at other times. Has no sickness or vomiting. The mucous membrane of the tongue is red and raw-looking; flakes of epithelial fur are readily detached from it.
The case was at once diagnosed as one of jaundice from suppression. Its mechanism being supposed to be identical to that of the cases discussed at [pages 25-9] under the head of jaundice arising from active congestion of the liver induced by blood-poisoning, a dose of calomel and jalap was accordingly administered, with the view of removing the portal congestion, and with the most satisfactory result; for, notwithstanding the jaundice being complicated with scarlatina, a very decided improvement in the colour of the skin took place within twenty-four hours, the other symptoms remaining as before. March 10th. The calomel and jalap was repeated on the 4th, and since then the skin has gradually become paler. It is now scarcely tinged.
To return to the cases of epidemic jaundice; they, as I have just hinted, are due to a precisely similar cause—blood-poisoning—either the direct result of miasmata, or of contagion.
A further explanation of the reason why jaundice occurs in an epidemic form, may be found in the circumstance that in all febrile states of the general system some one or other of the internal organs is liable to become congested. For example, typhus is, as a rule, complicated with cerebral congestion, typhoid with mesenteric, ague with splenic, scarlatina with renal, and so on. It is not, however, necessary that the organs should be affected in the same relation to the disease as is here given. On the contrary, in one epidemic of typhus, the brain may be congested, in another the lungs, and in a third the liver; and so also with other fevers. Hence we can have little difficulty in understanding why epidemics of jaundice every now and then occur, seeing that they are but the secondary results of other epidemic affections, although, as occasionally happens, the jaundice is the chief, if not the only well-marked symptom.
ARTIFICIAL JAUNDICE.
What is the source of the tyrosine, and leucine found in the urine, in cases like those previously described? Being well aware that the physiologist has it in his power to produce almost any pathological state or artificial disease at pleasure, I set about imitating on an animal the effects produced in the human subject by obstruction of the bile-ducts. Hitherto, artificial jaundice has been usually induced either by ligaturing the gall-ducts or injecting bile into the circulation; but as both of these methods were in the present instance objectionable—the first on account of the constitutional disturbance liable to be induced by the severity of the operation; the second from the bile being all at once thrown into the circulation, and thereby producing toxic effects, besides the danger of its too rapid elimination by the urine—I adopted another plan, which came much nearer to the state induced by disease in man—I took the bile of three healthy dogs, and injected it under the skin of a fourth. In this case the effects of the operation were almost nil, and the bile was at the same time placed in a position favourable for its slow absorption, just as in the human subject. During the first two days the animal remained comparatively well, the urine was normal in appearance, and contained neither bile-pigment, nor bile-acids. But on the third day the animal became ill, and on the fourth jaundice set in. He died on the fifth. After death the urine was found to contain not only bile-pigment, and bile-acids, but also the diseased products, leucine, and tyrosine; and what was more interesting still, the urine was loaded with sugar, just as occurred in the case imitated.
It will be remembered that in speaking of the bile-acids, I mentioned that while glycocholic acid is a crystalline, taurocholic is a non-crystalline substance. Tyrosine, and leucine stand in a similar relation to each other; tyrosine being crystallizable, leucine non-crystallizable. Now, taking this fact into account, together with the fact, that when the bile-acids are allowed slowly to enter the circulation, they reappear in the urine, accompanied with tyrosine, and leucine; and also with the third fact of these latter substances being found in the liver when the biliary function is interfered with, I am inclined to look upon tyrosine, and leucine as the products either of the arrested, or of the retrograde metamorphosis of glycocholic, and taurocholic acids. Moreover, I have found in one case, after injecting bile in the way before mentioned, into the cellular tissue, crystals of tyrosine spontaneously form in the bile taken from the animal's gall-bladder after death, and merely allowed slowly to evaporate. This result strengthens the foregoing opinion.
Frerichs states that he has never detected the biliary acids in the blood, even after bile had been injected into the circulation. In a remarkable case where 1 oz. of ox-bile killed a dog in less than five minutes from the time it began to be slowly injected into the jugular vein, I detected the bile-acids in a clear extract of the blood, with facility. This leads me to mention that, contrary to the statement of Frerichs, and in accordance with that of Kühne, the injection of the pure bile-acids into the blood is very dangerous, and that even the injection of pure bile into the cellular tissue, often proves fatal in the course of twenty-four hours, thereby showing that the constituents of the bile are highly poisonous.
In illustration of these facts I may cite the following experiments:—