respiratory organs become prominent. The mucous membrane of the mouth and
the nose, as well as that of the rectum and vagina, becomes reddened,
either in patches or diffusely, and assumes a scarlet hue. The discharges,
at first firm, become softer, and soon diarrhea sets in. This is said to be
one of the most constant symptoms. The rectum may become everted and
paralyzed, and the bowels move spontaneously. The discharges become fetid,
viscid, and streaked with blood. Coughing is a common symptom, and by some
is considered characteristic. It is associated with discharges from the
nose and vagina and dribbling of saliva from the mouth. The eyes also are
affected. There is an increased formation of a viscid secretion which flows
down the face.
Another series of changes prominent in some epizootics and mild or absent
in others are the ulcers, or so-called "erosions," in the mouth. These
begin as red patches and streaks. The mucous membrane in such localities is
converted into a grayish-white slough, which, when shed, leaves a small
erosion, or ulcer. At the same time similar changes may go on in the skin
of the thighs, the udder, or the scrotum, or about the vagina, which lead
to small sloughs.
In severe cases, which are the most common in the susceptible cattle of
western Europe, death ensues four to seven days after the first appearance
of the disease, and is preceded by great emaciation and debility, fetid,
purulent discharges from the nose and mouth, and the relaxed rectum and
vagina.
After death, if the animal is opened and the organs carefully examined, the
chief changes are found in the digestive organs. The lining membrane of the
mouth and pharynx is covered with mucus, is reddened in spots, and shows
superficial, yellowish-gray, cheesy patches, which represent dead tissue,
and when removed expose ulcerated depressions. The same reddening in spots
and the yellowish-gray, cheesy deposits or patches are found in the fourth
stomach, the small intestines, and more rarely in the cecum, while the
third stomach, or manyplies, is more or less impacted with dry, hard feed.
Similar changes may be found on the mucous membrane of the nasal cavity,
larynx, trachea, the uterus, vagina, and rectum. The lungs may be injected,
edematous, or pneumonic. The heart muscle is pale and flabby, and
frequently hemorrhages are observed in its internal membrane. The liver may
be pale or injected with blood, and at times shows hemorrhages beneath its
capsule. The bile is thin and watery in consistence. The kidneys may be
inflamed or contain small hemorrhages within their substance or under the
capsule. The lymphatic glands may be swollen and injected or even
hemorrhagic.
_Treatment._--On account of the danger of spreading the infection, neither
medicinal treatment nor inoculation is permitted in European countries,
with the exception of Russia, where the disease is more generally diffused.
The most effective method of exterminating rinderpest in those districts in
which the disease is not indigenous has been found to be the slaughter of
all affected and exposed animals. Where the disease is general, successful
efforts adopted for its control have followed the immunization by
inoculation of the exposed animals and a strict application of appropriate
sanitary measures. This protective inoculation has been practiced with very
gratifying results in Russia, South Africa, and in the Philippine Islands.
An active immunity is thus induced in susceptible animals which lasts until
the danger from exposure to the disease is over. This immunity may be
attained (1) by the inoculation of pure bile from an animal which recently
died of rinderpest, (2) by the inoculation of glycerinated bile, followed
by pure bile or virulent blood, or (3) by the simultaneous inoculation of
strong standardized serum and virulent blood.
The latter method has been adopted by the United States Government in its
endeavor to exterminate the disease in the Philippines, and to protect the
cattle and carabaos against rinderpest after their importation into those
islands. Owing to the existence of this and other infectious diseases in
the Philippine Islands, an order has been issued by the Department of
Agriculture prohibiting the landing of any live stock or animals of any
kind from the Philippines at any of the ports of the United States or the
dependencies thereof. This prohibition removes the greatest source of
danger to which the United States is exposed as the result of its
intercourse with the islands. The introduction of rinderpest from those
countries from which we import animals is rendered extremely improbable,
especially in live animals, owing to its short period of incubation and to
the 90-day quarantine for cattle (counting from date of shipment) and
15-day (counting from date of landing) quarantine for sheep and other
ruminants and swine which are at present enforced in the United States at
all ports of entry.
FOOT-AND-MOUTH DISEASE.
[Pl. XXXIII.]
Foot-and-mouth disease, also known as aphthous fever, epizootic aphtha, and
eczema contagiosa, is an acute, highly communicable disease chiefly
confined to cloven-footed animals and characterized by an eruption of
vesicles or blisters on the mucous membrane of the mouth and on the skin
between the toes and above the hoofs. The vesicles rupture, forming
erosions and ulcerations; there are also salivation, tenderness of the
affected parts, loss of appetite, lameness, emaciation, and diminution in
the quantity of milk secreted.
The tremendous ravages of the disease are seen in the number and variety of
the species attacked. While it may be regarded as essentially a disease of
cattle, hogs would seem to be as easy a prey. Almost in the same grade of
receptivity are sheep and goats. Next in order of susceptibility come the
buffalo, American bison, camel, chamois, llama, giraffe, and antelope.
Horses, dogs, cats, and even poultry may occasionally become infected with
the disease, the last three being particularly dangerous as carriers of the
contagion. Man himself is not immune, and the frequency of his infection by
coming in contact with diseased animals is established by numerous
observations.
As with other communicable diseases, the source and origin of
foot-and-mouth disease have given rise to much speculation. The disease
had been known in Europe for centuries, but it was not until comparatively
recent years that the erroneous conceptions of its spontaneous origin as a
result of climatic and meteorological conditions, exhausting journeys,
etc., were abandoned. It is now conceded that foot-and-mouth disease is
propagated by a specific virus and that every outbreak starts from some
preexisting outbreak.
So far investigators have been unable to identify or isolate the specific
organism causing the disease, although numerous attempts have been made to
cultivate and stain it by laboratory methods. Experiments have shown that
the virus will pass through standard germ-proof filters, thus indicating
its minute size and the reason it has not been detected by the staining
methods. The contagion may be found in the serum of the vesicles on the
mouth, feet, and udder; in the saliva, milk, and various secretions and
excretions; also in the blood during the rise of temperature.
A wide distribution of the virus and a rapid infection of a herd is the
result. Animals may be infected directly, as by licking, and in calves by
sucking, or indirectly by such things as infected manure, hay, utensils,
drinking troughs, railway cars, animal markets, barnyards, and pastures.
Human beings may carry the virus on their shoes and clothing and transmit
it on their hands when milking, since the udder is occasionally the seat of
the eruption. It may also be carried by dogs, cats, rats, chickens,
pigeons, etc. Milk in a raw state may also transmit the disease to animals
fed with it.
The observations made by some veterinarians would lead us to suppose that
the virus is quite readily destroyed. It is claimed that stables thoroughly
cleaned become safe after drying for a short time; hence, litter of all
kinds, such as manure or soiled hay and straw, may remain infective for a
longer time because they do not dry out. Other authorities maintain that
the virus is quite tenacious and may live in stables even so long as a
year. They also state that animals which have passed through the disease
may be a source of infection for several months after recovery.
Unlike most other infectious diseases, foot-and-mouth disease may
repeatedly attack the same animals. The immunity conferred by an attack is
of limited duration.
The period of incubation (that is, the time between the exposure of an
animal to infection and the development of the disease) is variable,
usually from three to six days. The disease may appear in 24 hours, or, in
exceptional cases, not for 18 days or even longer.
_Losses._--The highly contagious character of foot-and-mouth disease and
its rapid spread to practically all exposed susceptible animals lead to
heavy losses. Since the mortality is comparatively low, ranging from only 3
per cent or less in mild forms to 30 or 40 per cent in malignant cases, the
havoc caused by the pestilence is sometimes underestimated. But there are
other sources of loss which are much more important than the actual
mortality. The fever and the difficulty of eating cause a rapid and extreme
loss in flesh and a lessening or cessation of the milk secretion. The
udders often become inflamed and ruined by the formation of abscesses, and
cows affected in this way are sometimes rendered permanently valueless for
milk production. The inflammation of the feet may cause the horn to drop
from the toes, producing great lameness and lasting injury. Abortion is
frequent, and typical lesions have been observed in the newly born at
birth. Altogether these losses may amount to 20 or 30 per cent of the value
of the affected animals.
In addition there are indirect losses of a commercial nature. Dairy farmers
are put out of business for a time. Necessary quarantine restrictions
greatly interfere with the movement of live stock and such commodities as
hay, straw, hides, and farm produce. The business of the stockyards and
slaughtering centers is greatly interfered with. Sometimes it is necessary
to close stockyards for disinfection. The whole business of marketing,
transporting, feeding, and slaughtering is interrupted and deranged. Losses
of this character may reach enormous proportions.
[Illustration: PLATE XXXIII. FOOT-AND-MOUTH DISEASE.]
_The disease in other countries._--Foot-and-mouth disease has prevailed in
Europe for a great many years and has occasioned tremendous economic losses
there.
In Italy, France, Switzerland, Germany, and Russia the plague has existed
so long and has gained such a foothold that it is economically impossible
to fight it with the American methods of slaughter and disinfection, for to
do so would kill a large percentage of the live stock of those countries.
In consequence, little or no progress toward eradication has been made by
the authorities, though the severity of the disease in France appears to
have abated somewhat in recent months.
The outbreak which appeared in Germany in 1888 increased steadily until
1892, when it diminished gradually for a few years, but the disease again
reached great proportions in 1899. Thereafter it continued to exist to a
greater or less extent until in 1911 it attained a virulence unequaled
before. In that year 3,366,369 cattle, 1,602,927 sheep, 2,555,371 hogs, and
53,674 goats were affected. At that time the total number of cattle, sheep,
swine, and goats in Germany was only 51,319,000, while there were in the
United States 172,572,000, or between three and four times as many. It can
readily be imagined, therefore, what it would mean to the United States if
the disease were to gain the foothold here that it had in Germany, where,
as these figures show, approximately one out of seven of the animals
susceptible to the disease was affected.
The German Government, of course, has not left the disease to itself. It
attempted to control some outbreaks by the method of slaughter, but the
pestilence had gained too much headway and was too firmly established in
too many portions of the country for this method to succeed, and the
slaughter of the infected herds had to be abandoned. It now appears that
there is no hope of getting rid of it until the virus has worn itself out.
As soon as the animals' period of acquired immunity is over and favorable
conditions present themselves, the contagion breaks out with renewed
virulence. It has been impossible to control it by means of quarantines.
One scientist has asserted that unless all the infected farms were
absolutely isolated and the movement, not only of live stock but of
persons, absolutely prohibited, the disease could not be stamped out. Such
a quarantine is, of course, utterly impossible to enforce. In portions of
Germany the farmers, realizing that the disease is inevitable, make haste
to be done with it by exposing their stock deliberately to mild cases in
the hope that this will result in an immediate, mild attack and immunity
for several years thereafter. Such immunity, however, is very uncertain.
Great Britain, Denmark, Norway, and Sweden, on account of their
comparatively isolated positions, have been more successful in keeping out
the disease. The outbreaks in those countries have been more sporadic, and
by resorting to immediate slaughter the authorities have been able to stamp
them out. Great Britain has applied both quarantine and slaughter for many
years, and in an outbreak near Dublin in 1912 measures were adopted which
were even more stringent than any that have been used in the United States.
A British official (Cope) asserted in 1899 that after his country's
experience with this disease it was "more dreaded by the farmers and stock
raisers of Great Britain than cattle plague or pleuropneumonia, and they
are now willing and ready to put up with any restrictions, of however
drastic a character, considered necessary by the central department to
stamp it out." The British authorities have succeeded in suppressing each
outbreak, but reinfection often occurs from the neighboring continent. At
the present time (April, 1922) Great Britain is having a siege of the
disease, but is applying vigorous measures for its suppression.
In November, 1906, the disease reached Belgium from France, where it was
quite prevalent, and by the end of the year every Province in Belgium was
affected, and the Netherlands as well. Efforts to eradicate it from Belgium
were unavailing. The Netherlands apparently succeeded in stamping it out
for about six months, but it reappeared there.
The disease is also more or less prevalent in Central Europe, Spain, and in
the Balkan countries.
Australia and New Zealand have remained free from it.
We have less accurate information regarding Asia and Africa, but the
disease is known to prevail in Japan and China and in the Philippine
Islands, and it is doubtful whether any considerable part of the Orient is
free from it.
In South America it is reported as common in Brazil, Argentina, and
Uruguay, and it probably exists in other countries.
Canada and Mexico are fortunately free from the disease.
_Outbreaks in the United States._--Foot-and-mouth disease has appeared in
the United States on six different occasions--1870, 1880, 1884, 1902, 1908,
and 1914.
An extensive outbreak in 1870 was introduced by way of Canada, where the
infection was brought by an importation of cattle from Scotland. It spread
into the New England States and New York and appears to have been arrested
within a few months. Its failure to spread more extensively and its early
disappearance have been ascribed to favorable conditions, such as the
movement of live stock from west to east, the limited trading at that
period as compared with the present time, the restriction of traffic by
winter weather, and the infrequency of travel which obtained at that time
among people.
About 1880 two or three lots of animals affected by this disease were
brought to the United States, but there was no extension from the animals
originally affected.
In 1884, at Portland, Me., there was a small outbreak caused by imported
cattle, and the disease spread to a few herds outside the quarantine
station. Owing to the small number of animals affected and the limited area
of territory covered by the disease, it was easily controlled by the
ordinary measures of quarantine and disinfection.
It will be observed that in all these early outbreaks the contagion was
introduced with imported animals. Since the development of a stringent
system of inspection and quarantine of imported live stock, no instance of
that kind has occurred. On subsequent occasions the infection has evidently
been brought in with contaminated products or materials and not by means of
live animals.
In November, 1902, the disease was discovered in Massachusetts and Rhode
Island. The earliest cases were traced to Chelsea, Mass., near the docks,
and it was suspected for a time that the infection was brought in with
foreign shipping, by some such means as hay, straw, halters, ropes, hides,
hair, wool, etc. Later developments, however, and especially investigations
into the cause of the 1908 outbreak, led to the belief that a more probable
source of the infection was cowpox vaccine virus imported from a country
(probably Japan) where foot-and-mouth disease existed, the vaccine virus
being contaminated with the virus of foot-and-mouth disease.
A Federal quarantine was declared by the Secretary of Agriculture on
November 27, 1902, as soon as the nature of the disease was established,
and steps for eradication were at once taken by the Bureau of Animal
Industry of the United States Department of Agriculture in cooperation with
authorities of the affected States. The methods followed consisted of
inspection to trace and detect the disease, quarantine of infected premises
and territory, slaughter and burial or burning of diseased and exposed
animals, and disinfection of premises.
This outbreak involved Massachusetts, New Hampshire, Vermont, and Rhode
Island, and was eradicated in about six months. Two hundred and forty-four
herds, including 4,712 cattle, were found infected. Of these, 205 herds
with 3,872 cattle, as well as 360 hogs and 220 sheep and goats, were
slaughtered. The cattle infected but not slaughtered were those that either
died or completely recovered before slaughtering could be carried out. The
animals slaughtered were valued at $184,155.10, and the Federal Government
reimbursed owners to the extent of 70 per cent, or $128,908.57. It is
understood that the States paid the remainder. The total cost to the
Department of Agriculture of stamping out the disease was about $300,000.
The next appearance of the foot-and-mouth disease was early in November,
1908, when it was observed in cattle near Danville, Pa. A Federal
quarantine was issued November 12. The infection was traced back to the
stockyards at East Buffalo, N. Y., and to Detroit, Mich. The disease
appeared in the States of Michigan, New York, Pennsylvania, and Maryland. A
careful and thorough investigation made by Mohler of the Bureau of Animal
Industry and Rosenau of the Public Health Service demonstrated that the
outbreak started from calves used to propagate vaccine virus at an
establishment near Detroit, and that the source of the infection was
contaminated Japanese vaccine virus.
Vigorous measures of eradication similar to those employed in 1902-3 were
at once put into effect and the disease was stamped out in about five
months at an expense of about $300,000 to the Department of Agriculture,
and of about $113,000 to the States. The inspectors made 108,683 visits to
farms, stockyards, etc., and inspected more than 1,500,000 animals
(including reinspections). One hundred and fifty-seven premises were found
infected, and 3,636 animals (2,025 cattle, 1,329 hogs, and 282 sheep and
goats), valued at $90,033.18, were slaughtered. Owners were reimbursed for
the value of their animals and property destroyed, one-third being paid by
the States and two-thirds by the Federal Government.
The latest invasion was discovered in the vicinity of Niles, Mich., in
October, 1914, after it had evidently been under way since August of the
same year. This is the most serious and extensive outbreak ever known in
this country. The disease extended to 22 States and the District of
Columbia, at places ranging from the Atlantic to the Pacific coasts. The
work of eradication was not completed for more than a year. The affected
States were Connecticut, Delaware, Illinois, Indiana, Iowa, Kansas,
Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Montana, New
Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island,
Virginia, Washington, West Virginia, and Wisconsin. Illinois had the
largest infected area and the largest number of animals affected. The Union
Stock Yards at Chicago became infected and were a source of dissemination
of the contagion north, east, south, and west. These and other yards found
infected were closed temporarily and disinfected.
The first Federal quarantine was issued October 19, 1914. A campaign to
check the spread of the disease and to stamp it out was immediately begun
by the United States Department of Agriculture in cooperation with the
State authorities. Quarantines against the movement of animals and certain
materials from the infected areas were declared, shipments were traced,
rumors investigated, and thorough inspections made in an effort to discover
all infected stock. As measures of eradication, diseased herds were
slaughtered and buried and the premises disinfected. The owners of live
stock and other property destroyed on account of the disease were
reimbursed to the extent of the appraised value, half of which is paid by
the Federal Government and half by the State. There were slaughtered
172,720 animals (76,575 cattle, 86,492 swine, 9,511 sheep, 133 goats, and 9
deer), in 3,482 herds. The total appraised value of these animals was more
than $5,800,000. The expense to the Federal Government of eradicating this
outbreak was about $4,540,000.
_Symptoms._--In three to six days, or even longer, after the exposure of
the animal to the infection the disease makes its appearance. It is usually
first indicated by the animal suffering from a chill, quickly followed by
an invasion of fever, which may cause the temperature to rise as high as
106∞ F. These symptoms are not always present, or may be in so slight a
form as to escape notice. Following this in one or two days it will be
noticed that small vesicles or blisters about the size of hempseeds or peas
are making their appearance upon the mucous membranes of the mouth at the
border and upper surface of the tongue near the tip, the inside of the
cheeks, on the gums and the inner surface of the lips, or on the margin of
the dental pad. These little blisters contain a yellowish, watery fluid and
gradually become more extensive as the disease advances. Soon after the
eruptions have appeared in the mouth of the animal considerable swelling,
redness, and tenderness will be noticed about the feet, at the coronet, and
between the digits of each foot. A day or two later eruptions similar to
those within the mouth make their appearance upon these swollen regions of
the foot, and at this stage it is usual to find that like lesions have made
their appearance upon the perineum of the victim. In the case of milk cows
the udder, and more particularly the teats, show the same vesicular
eruption, but the latter as the result of milking soon become covered with
reddened spots deprived of the superficial layer of skin and may develop
deep, obstinate fissures.