Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/217

Rh RABIES 199 RABIES, a virulent disease, developed primarily in and peculiar to the canine species. Its occurrence in the same manner in other carnivorous animals, as the fox, wolf, hyaena, jackal, raccoon, badger, and skunk, has been asserted ; but there is every probability that it is originally a disease of the dog. It is communicated by inoculation to nearly all, if not all, warm-blooded creatures. The trans- mission from one animal to another only certainly takes place through inoculation with viruliferous matters. The malady is generally characterized at a certain stage by an irrepressible desire in the animal to act offensively with its natural weapons, dogs and other carnivora attacking with their teeth, herbivora with their hoofs or horns, and birds with their beaks, when excited ever so slightly. In the absence of excitement the malady may run its course without any fit of fury or madness. Transmission of the disease to man produces HYDROPHOBIA (q.v.) or dread of water, but in animals this symptom is rarely, if ever, observed. Rabies has been known from the very earliest times, and serious outbreaks have been recorded as occur- ring among dogs, wolves, and foxes in different parts of the world, particularly in western Europe and in North and South America. It is very frequent in Europe and appears to be on the increase. France, Germany, upper Italy, and Holland evidently suffer more than other Con- tinental countries. England is becoming more frequently visited than before, though Scotland and Ireland are much less troubled than England. Spain is also sometimes severely scourged by it; but it is rare in Portugal. On the American continent it is well known, though on the eastern side of the Andes it is rarely if ever seen ; and it has never been heard of in Quito. In the West Indies in Hispaniola, Jamaica, Domingo, Havana, Guadaloupe, and Hayti as well as in Ceylon, it is frequently wit- nessed, and in 1813 it was introduced into Mauritius. It exists in North and South China, and has been reported in Cochin China and the kingdom of Anam. It is fre- quent and fatal in India ; and it is by no means rare in Syria, Palestine, and Turkey. It has been observed in the Hijaz in Arabia, and in North Africa and Egypt. Hydrophobia has been reported in Algeria; but Rohlfs asserts that it is unknown in Morocco. Gibraltar and Malta have been seriously invaded at times, and in Sweden, Denmark, Norway, Russia, and Lapland it has been fre- quently seen in an epizootic form; but it is not yet positively decided whether it exists in the Arctic regions. Steller and Erman assert that it is unknown in Kam- chatka and Greenland ; but Hayes (The Open Polar Sea) gives us the particulars of an outbreak of disease in South Greenland, which persisted for several years, caused him the loss of his sledge-dogs in 1870, and in 1872 extended from Smith's Sound to Jakobshavn, threatening the utter extinction of the species, and with it the dis- appearance of the Eskimo. In most of its features it appeared to be rabies. The scourge is unknown, accord- ing to reliable evidence, in Australia and New Zealand, Tasmania, the Azores, and St Helena, as well as the island of Madeira ; it has not been seen at Sumatra, nor in East, South, and West Africa, nor in the island of Reunion. Rabies (hydrophobia) is almost invariably fatal in man, and in the dog it nearly always terminates in death, though instances of recovery are recorded ; and it is extremely probable that in those cases in which people have been bitten by dogs and subsequently perished from hydro- phobia, without the animals themselves offering any marked indications of illness either at the time or afterwards, these have been suffering from a mild form of the disease. It is also fatal to horses, cows, pigs, goats, and cats, but not to fowls, many of these recovering from accidental or experimental inoculation. Indeed rabies varies consider- ably in intensity and in the character of its symptoms in different species of creatures. Pasteur has shown that, if it is transmitted from the diseased dog to the monkey and ultimately from monkey to monkey, at each trans- mission it becomes more attenuated in virulence, and remains so attenuated when passed again to the dog, rabbit, or guinea-pig, nor will it any longer produce the disease in dogs by hypodermic inoculations. Even inocu- lation by trepanning the cranium, which is so infallible in conveying rabies, may produce no result, the dog thence- forward being protected, and no longer capable of receiving the disease. On the other hand, the rabific virus is in- tensified when passed from rabbit to rabbit, or from guinea-pig to guinea-pig ; and after several transmissions through the bodies of these animals it regains the maxi- mum virulence which it possessed before it was enfeebled by being passed through the monkey. And the same thing holds with respect to the virulence of the ordinary rabid dog : when virus which is far from having reached its maximum intensity is conveyed to the rabbit, it requires to be passed through several of these animals before it reaches its maximum. It may be mentioned that the disease is not readily conveyed from man to animals, either accidentally or experimentally. The virus appears to exist in greatest intensity in the salivary glands and their secretion, in the brain and spinal cord, and perhaps to a lesser degree in the blood ; doubtless it exists also in other fluids and tissues of the diseased animal. The principal alterations found in the bodies of rabid animals after death are located in the spinal cord, especially its upper portion, the medulla oblongata, certain parts of the brain, and the salivary glands, more particularly the submaxillary and sublingual, less in the parotid. The stomach, kidneys, and other organs also present altera- tions which are more or less significant, especially the former, in which foreign bodies, as hair, wood, stones, earth, pieces of cloth, &c., are very frequently found. But the nature of the lesions, as well as the symptomato- logy, shows that the action of the poison is more especially exerted on the brain or spinal cord, though the eighth pair of nerves, and branches of the fifth and seventh pairs, are not involved in animals, as in man. The period in which the symptoms of the disease become manifest, especially after accidental inoculations, as bites, varies extremely ; indeed there is no disease in which the period of latency or incubation is more variable or pro- tracted, this being sometimes limited to a few days or weeks and extending in rare cases to more than twelve months. In experimental inoculations the period is greatly shortened and the results more certain, all the more so if the virus is introduced into the cranial cavity by trepan- ning, or into the blood-stream by intravenous inoculation. In accidental inoculations, as in wounds from rabid dogs, a certain but varying percentage escape. This immunity may be due to natural non-receptivity, to the wound not having been inflicted in a very vascular part, or to the saliva having been expended from frequent bites on other animals, or intercepted by clothing, hair, wool, &c. Symptoms. The disease has been divided into three stages or periods, and has also been described as appearing in at least two forms, according to the peculiarities of the symptoms. But, as a rule, one period of the disease does not pass suddenly into another, the transition being almost imperceptible ; and the forms do not differ essentially from each other, but appear merely to constitute varieties of the same disease, due to the natural disposition of the animal, or other modifying circumstances. These forms have been designated true or furious rabies (Fr. rage vrai ; Genn. rascnde Wuth) and dumb rabies (Fr. rage mue ; Germ, stille IVuth). The malady does not commence with fury and madness, but in a strange and anomalous change in the habits of the dog : it becomes dull, gloomy, and taciturn, and seeks to isolate itself in out-of-the- way places, retiring beneath chairs and to odd corners. But in its retirement it cannot rest : it is uneasy and fidgety, and no