AGRICULTURAL EXTENSION SERVICE
By OLIVER F. GOEN, DVM
Assistant Extension Animal Industrialist
Brucellosis is a disease of animals and man that has been
prevalent in cattle, goats, and swine for centuries. There are
three types of the disease: (1) Brucella mellitensis-most com-
monly found in milk goats, (2) Brucella suis-most commonly
affecting swine, and (3) Brucella abortus-most commonly af-
fecting cattle. Brucella suis and Brucella abortus may cause
undulant fever in man. The disease in man caused by Brucella
mellitensis is called Malta or Mediterranean fever.
Fig. 1.-Don't let brucellosis cheat you out of a calf crop.
Brucellosis is found the world over. It is found in the United
States in all areas where cattle and hogs are raised. Brucellosis
of goats is confined principally to the Southwestern states. In
man this disease is becoming increasingly common.
Method of Transmission
Cattle become infected with Brucellosis by coming into con-
tact with other cattle that have the disease. Herds may become
infected by introducing into the herd an animal that has the
disease or that has been exposed to the disease and has not yet
become actively infected. Usually, bulls do not transmit the
disease but they can become infected and sometimes Brucella
organisms can be passed from infected bulls to non-infected cows
in the seminal fluid. Brucella organisms are found in great
numbers in the afterbirth from cows that are infected. Dogs,
foxes, and other wild animals may spread the disease by drag-
ging aborted calves over the premises and burying them.
In swine, Brucella suis organisms may be eliminated in the
droppings and urine of infected animals. Infection of the uterus
is sometimes accompanied by a thin, whitish discharge from the
vagina which may serve as a source of infection to non-infected
hogs. Boars commonly transmit Brucella suis organisms to non-
infected sows through the seminal fluid.
All three kinds of animals-cattle, swine, and goats-may
eliminate Brucella organisms in their milk. Man may become
infected either by drinking the milk or by handling infected
animals or meat.
In cattle there are no characteristic symptoms. Some cows
will abort their unborn calves, but not all affected cows will do
so. Most cows will abort only one calf, but most pregnancies
thereafter are usually carried to term. Cows that have brucello-
sis, whether or not they abort their calves, still are a dangerous
source of infection for non-infected cows. In cows affected with
brucellosis there is a high percentage of retained afterbirths.
Bulls affected show a swelling of the testicles.
In swine the most characteristic symptom is abortion or the
birth of weak pigs. In many of these weak litters many pigs
may die soon after birth. Swelling of the testicles in the boar
occurs. Usually this infection is chronic.
As the act of abortion is not conclusive evidence that an
animal has brucellosis, it is impossible to tell by looking at an
animal if it has this disease. The most reliable test that we have
is the blood agglutination test. This test requires that a blood
sample be drawn from the jugular vein of the animal suspected
and carried or be sent to a diagnostic laboratory.
There is no known treatment for this disease in animals.
A vaccine has been developed by the Bureau of Animal In-
dustry which is essentially a strain of Brucella abortus organ-
isms (Strain 19) of very low virulence. Calves vaccinated be-
tween the ages of six and eight months as a rule have a resist-
ance that will in most instances protect the animal two or three
years. In a small percentage of cases the vaccination will not
take. These animals may take brucellosis at a later date. Even
when the vaccination takes, the immunity may break down if an
especially virulent source of infection is introduced into the
herd. The immunity of vaccinated animals gradually decreases
so that protection after three to five years is doubtful. Even
with all these limitations, calfhood vaccination is a valuable
asset in the brucellosis control program because these limitations
are the exception rather than the rule.
The Florida State Livestock Sanitary Board has adopted the
following plans for brucellosis control.
Plan A. Test and slaughter method, with or without calfhood
vaccination. This is the testing and sending to slaughter of all
animals reacting to the agglutination test. A calfhood vaccina-
tion program may be carried on with this plan.
Plan B. Test, calf vaccination, and temporary retention of
reactors. This plan interpreted means to test the animals and
vaccinate all calves six to eight months old to be kept as herd
replacements with Strain 19 Brucella abortus vaccine. Reactors
are temporarily retained until they can be disposed of for slaugh-
ter without excessive loss to the owner.
Plan C. Vaccination of calves six to eight months old with
Strain 19 Brucella abortus vaccine without testing any part of
Plan D. Experimental adult vaccination with Strain 19
Brucella abortus vaccine. This plan has a very limited applica-
tion. It is applicable only when there is a large percentage of
cows aborting their calves, as vaccination of these animals will
usually stop the abortions but will not cure the disease. Adult
cattle that are vaccinated will react to the agglutination test and
cannot be distinguished from cows that have brucellosis. In
some instances adult cows will contract this disease from being
vacccinated with Strain 19 vaccine and abort their calves. Raw
milk from all reactors, whether vaccinated or not, represents a
dangerous source from which man might become infected. It is
for these reasons plan D should be used with caution.
Plans B, C, and D should be only temporary programs. After
the incidence of brucellosis has been reduced through these
plans, Plan A should be adopted and complete erradication of
brucellosis from the herd attempted.
Grateful acknowledgement is given C. W. Reaves, extension
dairyman, for assistance in preparing and editing this leaflet.
COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
University of Florida, Florida State University and United States Department of
Agriculture, Cooperating. H. G. Clayton, Director.