Less simple or easy than in plagues. Germ survives in soil and water.
Extinction not always possible. Killing: conditions demanding it: when
unwarranted. Kill without shedding blood, or opening carcass. Body
burned: if buried, 5 feet deep, in porous soil, distant from wells,
ponds, and rivers. Fence graves, burn grass. Disinfection of hides,
litter, fodder, manure, excretions, stalls, etc.: of bodies that must
be moved, of buildings, yards, utensils, etc. Isolation of unaffected
on porous soil; surveillance. Sales interdicted. Milk, butter, cheese.
Immunization: by toxins which stimulate leucocytes to form defensive
products: antitoxins. Eosinophile cells, action of spleen, and liver.
Mellituria. Protection by a minimum dose: by weakened virus—modes of
lessening potency, Pasteur’s “vaccine”, its drawbacks and dangers, its
technique; by soluble toxins in sterile solution, author’s experience,
apparent failures, advantages. Drainage—Æration of land. Prevention of
importation and diffusion. Therapeutic treatment.
Prevention of anthrax in animals is equally important for the sanitation
of herds and human beings. It involves the purging from the anthrax
bacillus of the infected lands and the drinking supplies, and in this
respect the disease is much less amenable to thorough and speedy
extinction than is a simple plague in which the germ does not live and
multiply outside the animal body. In some localities the extinction of
the germ may be confidently counted on and secured; in others, it may be
impossible and other measures of protection must be resorted to.
_Killing of the Sick and Disposal of the Carcass._ This is not always so
imperative as in the obligatory parasitic infections, since the
destruction of the sick, still leaves the germ present in the soil and
water. If, however, the infection has just been introduced, on hitherto
uninfected soil, by the arrival of new animals, and, if the new location
is in any way favorable to permanent colonization by anthrax bacillus,
and, if the diseased and suspected animals cannot be kept secluded so as
to absolutely exclude these dangers, or again, if the diseased herd or
its remnant is to be moved on to another locality, slaughter is the
obvious sanitary measure.
The animal should be killed on the premises to avoid the danger of
scattering the infectious discharges in transit; it must not be bled,
nor cut open, as the admission of air determines the formation of the
resistant spore; and the carcass must be burned, boiled, or rendered in
superheated steam under pressure, or finally dissolved in strong mineral
acids. If buried, it must be in open, porous soil, well apart from any
well, pond, river, or bank where the liquids may leach out, and the body
must be wholly covered to a depth of at least five feet. The graves must
be well fenced in from all stock, for a number of years, and no forage
grown on them can be safely fed to animals, as the bacillus can be
brought to the surface by earth worms. I have known cattle to become
infected through licking the fluid which escaped above a stratum of
clay, on the deep bank of a river, at some little distance from where an
anthrax carcass was buried in the surface sandy loam. A covering of coal
tar, chloride of lime or of sand charged with sulphuric acid is an
admirable precaution.
As a measure of economy the skins may be removed, if at once, on the
spot, plunged for 12 hours in a 5 per cent. solution of carbolic acid,
or cresyl, or creolin, or in a two per cent. solution of sulphuric acid,
and, if the knives and other implements used are placed in boiling water
for half an hour. The same will apply to fleeces.
_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.
_By Weakened Virus._ This has been secured by heating the defibrinated
blood to 55° C. for ten minutes (Toussaint); Pasteur, Chamberland and
Roux accomplished the same end by making anthrax cultures at 42° to 43°
C. in presence of air; Chauveau by subjecting the virulent culture for
eight days to oxygen under a pressure of 8 atmospheres at a temperature
of 38° C.; Chamberland, Roux and others have cultivated the bacillus in
weak antiseptic bouillons as phenic acid (1:600 or 1200), bichromate of
potash (1:2000 or 5000), sulphuric acid (2:100).
Other methods have been followed, as growing the bacillus in the blood
or serum of immune animals (dog, chicken, pigeon, white rat, frog).
Of these different methods that of Pasteur has been most extensively
adopted. The temperature of culture (42° C.) prevents the formation of
spores and the duration of exposure to air gradually lessens the
virulence until in 12 or 13 days it is not fatal to the Guinea pig and
after 31 days it fails to kill the young mouse. Thus preparations of
varying grades of virulence, and adapted to the varying susceptibility
of different animals, are secured. The protective inoculation is made by
preference in spring, when there is less chance of complication by a
coincident accidental infection, it is to be avoided if possible in
animals at hard work, in advanced gestation, in full milk, in extreme
youth, or in ill health. To secure the best results it should be
repeated with a stronger preparation 12 to 15 days after the first
injection. The acquired immunity lasts a year and over, and it is
probably perpetuated by new and non-fatal doses taken in casually, on
the anthrax pastures. Hundreds of thousands of live stock in all parts
of the world have been treated in this way with the result of reducing a
mortality of two, five or ten per cent. to insignificant proportions. It
can only be safely adopted on anthrax lands, as elsewhere it may lead to
the stocking of new areas with a malignant germ which in young and
susceptible animals reacquires its original virulence.
It can never be safely ignored that we are dealing with the living seed
of a most deadly infection. Though robbed of a large part of its
virulence by artificial culture at 107:5° F., yet many accidental
conditions, contribute to a relapse to its original potency, and when it
has once killed a victim, the reacquired virulence is usually
persistent. If the virus employed for protective purposes in cattle and
sheep, is inoculated on Guinea pigs of 1 to 30 days old, from these on
those of several months, and from these last on sheep, the virulence is
constantly and persistently enhanced. The same is true of the microbe
which is inoculated on a succession of pullets of steadily encreasing
ages (Roux and Chamberland), or on a succession of pigeons
(Metchnikoff). The germs reinforced in potency in any such way are
liable to be the starting points for dangerous infections in animals and
permanent contamination of soils and waters. Fortunately an occurrence
of this kind is rare, yet with a wide application of the Pasteurian
inoculation the opportunities also are great, and with the free sale and
distribution of the mitigated virus (anthrax “vaccine”), the evil may
grow indefinitely. The method departs from the ideal one, aimed at a
final extinction of the disease, and accepts in place a mere temporary
protection of the herd or flock, and though in this affection
eradication cannot always be secured, every effort should be made to
gain it and above all to prevent an encrease of the area of infection.
_Technique._ The weakened virus (1st “vaccin”) is sold in tubes holding
enough for 100, 200, or 300 sheep. Of this ⅛ cc. is injected subcutem on
the inner side of the thigh of the mature sheep, and 12 or 15 days later
a similar dose of the stronger preparation (“2d vaccin”). For the ox or
horse double the amount (¼th cc.) is used, being injected behind the
shoulder, and on the side of the neck in the respective animals. The
dose is graduated in the different subjects according to the size and
age, yet a considerable latitude is permissible. The syringe must be
disinfected before and after inoculations by a 5 per cent. solution of
carbolic acid, or by boiling, and the nozzle should be dipped in strong
carbolic acid immediately before and after each insertion. This will
greatly obviate infection of the liquid used, and of the wound by any
virulent germs lodged on the surface of the skin. The liquid to be
injected should be used as soon as possible after preparation, and if
kept should be in a dark cold place, and if the tube is once opened the
whole of its contents should be used the same day,—never kept over. The
second, stronger preparation should never be used until the system has
been prepared for it by the use of the first.
_By the Soluble Toxins in Sterile Solution._ In 1884, in an outbreak of
anthrax in Skaneateles, N. Y., I drew blood from an anthrax cow,
subjected it to 212° F. for 30 minutes, dissolved out the soluble toxins
in boiled water, and injected the product subcutem, in the dose of 2 to
4cc. according to size, into every apparently healthy member of the
herd, excepting one, which was left as a check. The check animal died of
anthrax while all of the others escaped.
Since that time I have personally used it in every herd where
opportunity offered, and with equally good results. In an outbreak near
Elmira, Dr. Moore adopted it in a large dairy herd, and the disease was
suddenly arrested.
In several experimental cases (one cow and 2 Guinea pigs) at the N. Y.
S. V. College, the outcome was not so satisfactory and in a herd in
Oneida Co., N. Y., it is said to have failed to check the disease.
Notwithstanding these untoward results in other hands, I am still
confident that we have in this a measure of no small value, and worthy
of application in suitable cases. A certain percentage of failures in
immunization are to be looked for. Even cowpox vaccination is not always
protective against itself; I knew one man who was successfully
vaccinated every three years in a comparatively long series. Many
habitually self-limiting diseases relapse in particular individuals.
Even in the case of anthrax excess of glucose in the system, and the
lack of some unknown influence of the spleen are respectively
destructive of immunity. Even after the Pasteurian inoculation a certain
number of inoculated animals are lost, it may be between the first and
second injection, or it may be “two or three months” after the latter
(Galtier). We must also bear in mind that in an infected herd or flock,
there are always a certain number already infected at the time of the
protective inoculation, and as the protective conditions are slowly
established, through the action of the leucocytes, it is unreasonable to
expect that serious illness and death can be obviated in such animals.
In inoculation with the Pasteur lymph, the bacillus is held not to enter
the blood, a position supported by the researches of Bitter, Perroncito,
Wissokovicz, Lubarsch, Metchnikoff, Chamberland and Roux, so that the
resulting immunization must come from the toxins. Add to this that
Chauveau (1885), conferred immunity on a sheep by injecting
intravenously, anthrax blood, defibrinated and sterilized by heat:
Arloing obtained immunity in the sheep by injecting, subcutem, the clear
supernatant liquid from old bouillon cultures of anthrax, from which all
bacilli had been precipitated. Roux and Chamberland obtained the same
result by using the pulp of an anthrax spleen treated with essential oil
of mustard, so as to destroy the life of the bacillus, and then
evaporated in vacuo to remove the essence. Smaller doses proved
effective, than when the splenic pulp had been filtered or sterilized by
heating to 58° C.