The rabbit or guinea pig is used for demonstration in the laboratory. Guinea pigs respond to the virus more rapidly than do other animals and therefore they are especially useful in diagnostic work. Rabbits, however, on account of the convenient size and ease with which they are operated upon, are usually the choice in the production of material used in treating patients.
The director of one Pasteur Institute says, "We have two classes of patients to deal with in the Pasteur institute. The larger class, of course, are those inoculated by the bite of rabid animals, but we also have a few who are infected by the rabid saliva accidentally coming in contact with wounds already produced. In these accidental eases the disease is almost as likely to result as in those to whom the virus is directly communicated by the bite." The wounds considered most dangerous are the recent fresh wounds. The possibility of infection decreases with the formation of the new connective tissue which protects the ends of the broken nerve fibres. One must remember, however, that wounds over joints, especially on the hands, are likely to remain open for some time. A dog ill of this disease can give the disease to man through licking a wound. Such a case has been recorded. This dog licked the child's hands before it was known to be mad. The child died from the disease. As stated before ninety per cent of the cases are inoculated by the bites of rabid animals.
[INFECTIOUS DISEASES 243]
The wounds are considered according to their severity and location. Lacerating, tearing wounds upon uncovered surfaces, especially the head, are the most dangerous. This is due to the fact of the closeness of the brain and the large amount of infection in such a wound, and for this reason treatment should be immediately given. But smaller wounds should also be treated for the smallness of the wound furnishes no sure criterion as to the future outcome of the disease. All possible infections should be regarded as dangerous when considering the advisability of taking the Pasteur Treatment. The small wound has usually a longer period of incubation, because of the small amount of infection, still it may cause a fatal termination. A dog never develops rabies from a lack of water or from being confined or overheated during the summer months. A spontaneous case of rabies has never been known. It must be transmitted from animal to animal and the history of the case will point to a previous infection by a diseased animal.
Where rigid quarantine rules exist the disease does not occur. In Australia they quarantine every dog, that comes to that country, for six months, and in consequence they have never had a case of rabies. In Russia they have had many cases. In Constantinople the disease frequently "runs riot." France has lost as many as 2,500 dogs in one year. Before the Pasteur Treatment was instituted (in 1885) there was an average of sixty deaths in human beings in the Paris hospitals.
Belgium and Austria average one thousand dogs annually. There was a yearly average in Germany of four hundred dogs, dying of rabies, until the law requiring the muzzling of dogs was strictly enforced and since that time the disease is practically unknown. We do not have strict quarantine laws against dogs, and the result is death from hydrophobia in many states annually. It was formerly believed that rabies was a hot weather disease. The number of cases during the winter months of late years has disproved that belief, for the records of the institute for treatment of hydrophobia at Ann Arbor have shown a decrease of cases during the summer months. This was before 1908. This shows that rabies is not a hot weather disease.
[244 MOTHERS' REMEDIES ]
Ordinarily cases of rabies occur here and there (sporadic), but if the conditions are favorable epidemics break out. One dog may bite several dogs and these dogs bite others and thus spread the disease to many. Not every animal bitten by a mad dog develops the disease. The disease does not always follow the bite. Only about forty per cent of all animals bitten by a mad dog contract the disease. This is given by a noted authority. Statistics also show that in man the disease develops in only about twenty per cent of the cases in those who have been bitten by rabid dogs. But in dealing with those who have been bitten such measures should be taken as would be if they were certain of developing the disease; one cannot tell how much poison enters the system in such cases and preventive procedures should be taken. There are reasons why everyone who is bitten does not contract the disease.
The location and character of the bite must be considered. Bites on the head, neck and hands have been recognized as more dangerous, from early times, and such bites produce fatal results quicker than do bites on other parts of the body, and the reason is largely due to the fact that the other parts of the body are more or less protected by the clothing, and this clothing prevents the entrance of so much poison into the system. Bites on the head give a high mortality rate and are rapidly fatal. The close proximity to the brain is one reason.
The part the clothing plays in protection is clearly shown by the following quotation from an eminent authority: "In India where the natives dress very scantily, the mortality was exceedingly high up to a few years ago, at which time the British introduced the Pasteur laboratories. The clothing protects the body and it holds back the saliva and can be looked upon as a means of filtering the saliva of the rabid animal, most of the saliva is held back as the teeth pierce the clothing, so that upon entering the flesh the teeth are practically dry, and only a portion of the virus is introduced. Upon entering the wound this small amount of virus is further diluted by the tissue juices to the non-infectious point. We know from actual experimental work in the laboratory that the higher dilution will not kill."