Disinfection. All litter, fodder, manure, urine, and other excretions, or products; all stalls, feeding troughs, sheepfolds, covers, halters, harness, wagons, poles, shafts, and other objects used about the animals, or soiled by them or their products, should be disinfected by burning, flaming or scalding (boiling), when applicable, by one of the above-named disinfectants, by mercuric chloride (5:1000), by formalin, or other potent antiseptic. Extensive dung heaps, too wet to burn, may be sprinkled freely with strong mineral acids, or mercuric chloride in solution, piled into compact mass, covered with chloride of lime, and finally with a thick layer of earth, and fenced in from all stock.
If carcasses must be moved to the grave, rendering works, or elsewhere, they should be sponged with carbolic acid solution, formalin, or mercuric chloride, and each of the natural openings firmly plugged with tow or cotton soaked in the same material, so that no infecting material may drop on the way. They should on no account be dragged on the ground, but carried on a wagon or stone boat, which should be afterward carefully disinfected. Men or animals, entering an infected place, should be disinfected on leaving; especially hands and feet.
All roads, yards, and pastures where the sick have been, and, above all, where manure, urine, or saliva has fallen, should be subjected to thorough disinfection, or the surface layer removed and deeply buried. Where available, a concrete or asphalt floor should be placed in the buildings.
Isolation. Movement from Infected Ground. It has long been known that the movement of an infected herd from the contaminated pasture to another, will often, at once, check the development of new cases. In Sardinia and Auvergne the flocks and herds were yearly moved on the approach of autumn, from the rich valley, and bottom lands, to the drier hill pastures, to avoid or lessen the decimation that otherwise inevitably overtook them. This is in keeping with the enzoötic nature of the malady which arises more from the microbe preserved in the soil than from the sick animal direct. Two precautions are necessary in making such a change of locality: 1st, Animals already infected should not be moved on such new pasture; and 2d, the pasture to which the stock is moved should be entirely free from the impermeability (clays, hard pans), and saturation with water (swamps, basins, low bottoms), which would ensure the permanent preservation of any microbe planted there. Elevated, sandy, argilaceous or loamy soils are to be selected. To these the animals of the infected herd which by their appearance and thermometry may be pronounced sound, should be removed, and kept under careful supervision, especially as regards thermometric tests. Any showing symptoms of anthrax should be at once taken back to the infected herd. If they have stood in stalls, for milking or otherwise, these should be disinfected, and they should be carried in wagons, or driven by unfrequented roads. Their droppings should be carefully disinfected.
If, in the absence of anthrax symptoms, animals must be kept in the infected lot, or returned to it, they should be immunized.
Interdiction of Sales. No animal in the infected herd which shows a rise of temperature, should be sold even for slaughter. No animal should be sold for stock purposes until the disease has completely subsided. Any animal in the infected herd, which shows no hyperthermia nor other sign of anthrax, may be sold for immediate slaughter, subject to a critical expert examination of the cadaver for anthrax. Milk, the product of an infected herd, and butter and cheese made from such milk, should not be used as food. If those members of the herd, that show no hyperthermia or other symptom of anthrax, can be held apart as a separate herd, in a disinfected place and under careful thermometric observation, their dairy products may be used.
Immunization. A number of different methods have been practiced of rendering animals refractory to the bacillus anthracis, but all are apparently based on the production in the system of defensive products, as the result of a nonlethal poisoning with anthrax toxins. It is true of anthrax as of many other infections that a first attack protects against a second. In all animals there is a certain measure of defensive power against the bacillus anthracis, amounting in some cases to virtual immunity and in others having a very little effect. The object in immunizing is to stimulate to the increase of these defensive products in quantity or power until an ordinary dose of the bacillus will fail to colonize the tissues or the blood. In considering this subject a clear distinction must be made between the simple bactericidal and the antidotal or antitoxic products found in the serum of immune animals and the toxins which are produced by the bacilli. The soluble antitoxic and bactericidal agents found in the serum of the immune, may be employed for therapeutic purposes to preserve life in an animal which has received a lethal dose of the bacillus anthracis, but as these are rapidly eliminated from the system, their protective power is very short lived, and if some bacilli survive the period of their presence and potency, or if they are introduced into the system later, the animal may fall a victim to anthrax as if no such protective agent had been used. Behring showed that the blood serum of the white rat proves fatal to the bacillus anthracis, but Metchinkoff pointed out later that it must be brought in contact with the bacillus in order to prove effective, whereas if the serum and bacillus were injected at different parts of the body no protection was obtained. The antidotal or bactericidal action of the serum of an immunized animal acts at once, whereas a permanent immunity cannot be established before about fifteen days. The serum of the immune animal contains the following elements antagonistic to anthrax: Antitoxin or leucomain which may be poisonous to the bacilli, or chemical antidotes to their products: globulicidal principles which distort or disintegrate the blood globules and release their contents including the bactericidal nuclein, and probably others. All such agents when injected into the system are present only for a limited time and while they may be made subservient to a temporary immunity, they can give no permanent protection and must be considered mainly as therapeutic agents.
A permanent immunity must depend on a stimulation or education of the system to the production of these protective agents de novo or in increased quantity. This must be done by exposure of the tissues to the toxins of the bacillus anthracis, and is accomplished slowly. Precisely what tissues are stimulated to the production of the defensive agents is not fully known, though certain indications may be drawn from observant facts. The eosinophile cells of the blood are presumably important factors as the natural sources of the leucomaines. The spleen as the seat of important blood changes and as preëminently the seat of election of internal anthrax is probably involved. The dogs from which Bardach had removed the spleen were found to be three times as susceptible to anthrax as were the dogs that had not been operated on. Leo’s rats, in which he had produced mellituria by the administration of phloridzin were found to be much more susceptible to anthrax. The liver is also a favorite seat of election of internal anthrax. The products of the healthy liver, are probably in some measure protective.
No matter where the defensive products are formed, the practical problem is to secure their production without imperilling life.
By Minimum Dose. Chauveau and Colin secured this in the larger animals by intravenous injection of a minimum dose,—one or two bacilli. This is more lasting in effect if a second and stronger dose is injected some days later.