The principles and practice of modern surgery

by Roswell Park

Dumb hydrophobia is the more common form. Here paralysis appears much earlier and involves especially the lower jaw; the tongue falls out of the mouth; and the posterior extremities are quickly paralyzed. This form is much more quickly fatal than the other.

Animals thought to have hydrophobia should be kept by themselves in a secure enclosure and carefully watched, especially those known to have bitten men or other animals. If a suspected dog have been killed before the suspicion has been confirmed, the head and upper part of the neck should be removed for examination. Veterinarians claim that what they call the plexiform ganglion permits an almost certain diagnosis to be made. The presence of foreign bodies in the stomach of the animal is a corroborative feature. Diagnosis by subdural inoculation requires two or three weeks, and in at least one case a human patient died while waiting for diagnosis to be thus established.

Hydrophobia in man is rare in this country, yet is occasionally observed. Its etiology is as yet obscure. That a contagion vivum is present is positive, but its nature is uncertain. Negri, of Pavia, has recently described certain bodies observed in the nervous system of animals dead of hydrophobia which may offer the solution of the problem that has so long been sought. They are found in the protoplasm of nerve cells, but not in their nuclei. They are round or oval in shape, vary in size from 25 microns down to those which can be barely seen with the highest powers. They take ordinary stains.

Negri maintains that these bodies are parasites and he has invariably failed to find them in animals which did not have rabies. His work has been confirmed by a number of his colleagues, and bids fair to furnish a reliable and rapid means of diagnosis. The fact that the virus of hydrophobia will pass through a porcelain filter nowise contradicts the view that these bodies may be parasitic, for it is quite possible that they undergo different stages of development, in some of which they are small enough to pass even barriers of porcelain.

In fact it seems to have been positively demonstrated that these bodies described by Negri, in 1903, are diagnostic for rabies. They are most likely to be found in the horns of Ammon or the cerebellum. When found here, careful examination must be made of the Gasserian ganglion, where may be found the lesions first described by Van Gehuchten and Nelis, which consist of a proliferation of the endothelial cells to such an extent that the ganglion cells are first invaded and then destroyed, their places being taken by the new cells.

The Negri bodies have been generally regarded as protozoa and the specific cause of the disease. At all events, it seems possible always to successfully reproduce the disease in rabbits or guinea-pigs by inoculation with these bodies.

If examination shows neither the Negri bodies nor the lesions in the ganglion the presence of the disease can scarcely be suspected, and could only be proved by animal inoculations, which, however, would be advisable in doubtful cases where human beings have been bitten.

Symptoms.

—The period of incubation in man is variable, ten weeks being perhaps the average. It is shorter in children, as also when the bites are numerous. It is even stated that it may be as long as a year or more, during which time the poison seems to lie latent. When the active symptoms supervene there are, locally, discomfort about the wound, itching, heat, and peculiar unpleasant sensations. It is said also that vesicles may make their appearance in the neighborhood of the original lesion. As in animals, so in man, the disease may assume either the furious or the paralytic type. These cases are nearly all marked by mental depression and apathy, with complete loss of courage. The earlier symptoms are connected perhaps with the respiration, which is infrequent, while inspiration is halting and speech is interfered with. The facial appearance is often changed to one of anxiety, even despair. The muscles of deglutition are next involved in a combination of spasm and paralysis, and the act of swallowing is interfered with, sometimes made almost impossible. Although patients can swallow their own saliva, they find it difficult to swallow any foreign substances, such as water, etc. This is not due to the fear of water, as the term “hydrophobia” would imply—this being an absolute misnomer—but is due to reflex spasm excited by the attempt. It is accompanied by more or less sense of suffocation and palpitation of the heart. Indeed, a paroxysm of this kind may be precipitated by the attempt to swallow, so that the patient instinctively refuses water or any other fluid. Reflex excitability is also very great, and a breath of air or a trifling disturbance may precipitate a paroxysm, almost as in extreme cases of tetanus. As the case progresses the saliva becomes more tenacious and viscid, faucial irritation more marked, and the attempts to expel the secretion, along with the disturbed respiratory efforts, have given rise to the foolish lay notion that these patients bark like dogs. The paroxysms, as the case progresses, become more marked, the patient more restless, until, later, furious mania or muttering delirium is present, to be followed by prostration and paralytic phenomena, muscle tremor, etc., and death.

The paralytic form in man, as in dogs, is marked by the much earlier paretic phenomena, anesthesia, and, finally, respiratory paralysis which terminates the case. Curtis and others have insisted that the hydrophobic paroxysms are not convulsions in the ordinary sense of the term, but are due to temporary inhibitions of the most important respiratory and cardiac centres as the result of peripheral impressions. He likens them to the shock of a shower bath.