Postmortem Changes.
—Postmortem changes are indistinct and only suggestive. They consist for the greater part of a sort of vacuolous degeneration of the ganglion cells of the nerve centres—most prominently in the medulla, next in the hemispheres, and then in the spinal cord. There is hyperemia, with minute ecchymoses, with infiltration of the adventitia of the vessels and perivascular extravasation. The changes met with in the other viscera bear no constant relation to symptoms. Nevertheless, Gowers holds that because of the location of the lesions and their intensity in the neighborhood of certain nerve nuclei we have here a distinguishing anatomical character of the disease.
The toxin (as we may call it for the lack of a better term) seems to be transmitted much as is that of [tetanus] (q. v.), along the afferent nerves to the cells of the anterior horns of the cord.
Diagnosis.
—As between hydrophobia and tetanus diagnosis is not difficult, as already described. In certain hysterical individuals nervous paroxysms, largely due to fright, may be precipitated by dog-bites and other incidents or accidents. In these cases there is rarely such a period of incubation, and in a true hysterical case there will be no such mimicry of this awful disease. A condition known as lyssophobia (fear of hydrophobia) has been described. It is seen in hysterical subjects. It is said to have even been fatal, but this must have been from other complications.
Treatment.
—There is no authenticated case on record of recovery after medication by drugs. It is probable that recovery has never followed anything but the modern inoculation treatment.
The only successful treatment for this disease has been elaborated as the result of the labors of that indefatigable French savant, Pasteur, and is among the glorious triumphs of laboratory research, against which it is so often charged that it is not practical in its results. It is in some respects a curious commentary on the study of infectious disease that we can secure and work with the peculiar virus of hydrophobia, and at the same time be utterly unacquainted with its true character. To this fact is due the modern cure. It is based upon the fact that the virus is not only in the saliva, but also in the nervous system of animals suffering from this disease, and that its effects are intensified and hastened by inoculation directly into the cerebral substance. Accordingly, when a diagnosis of hydrophobia can be reasonably well established, no time should be lost in sending the patient to one of the “Pasteur Institutes,” to be found now in most of the great centres, there to undergo a regular course of treatment. It was reported that in the Institute in Paris, between the years 1886 to 1894, there were treated a total of 13,817 cases, and that the mortality was 0.05 per cent. Of course but a small proportion of these really had or would have developed the disease.
Virus obtained from the brain or cord and inoculated into the dura of another animal quickly precipitates the disease. It is, moreover, modified in virulence as it passes through successive animals of certain species—for example, monkeys. It is increased by passage through rabbits, and the period of incubation thereby shortened. The weakest virus can by proper handling and manipulation in this way be so intensified as to produce disease within seven days after inoculation. Desiccation reduces the virulence, and preparations from the cord of an infected animal may be attenuated to almost any desired extent by drying. By inoculating a dog or a rabbit with virus prepared from this weakened source, and daily making injections from stronger and stronger preparations, it is in the course of a couple of weeks rendered practically immune to the disease. Animals thus made immune are trephined and the virus injected beneath the dura, by which more certain results are obtained. The treatment consists in using a section of a rabbit’s spinal cord, 0.5 Cm. in length, rubbed up in 6 Cc. of sterile salt solution. Half of this amount is injected each day into the flank of the patient. The cord first used is one that is thirteen or fourteen days old, which has been kept suspended in a sterile flask, over caustic potash, in order to assist in its desiccation. The next day a cord one day younger is used, and so on until by the twelfth day of treatment the cord is one only two days old, and at the end of two weeks a fresh cord can be used which would convey the disease had it been used first. If this course of treatment can be carried through before the first symptoms of the disease appear, the antidote has gained complete mastery over the infecting agent and the patient is saved.