Brucellosis Updates and Information
Brucellosis is a contagious disease of livestock that also affects humans. The disease is also known as contagious abortion or Bang's disease in livestock. In humans, it is known as undulant fever because of the intermittent fever accompanying infection. It is one of the most serious diseases of livestock, because it spreads so rapidly and it is transmissible to humans.
The disease is caused by a group of bacteria known as
Brucella. more... Within this group there are three species of
concern: Brucella suis, which predominately affects swine
and reindeer, but can also affect cattle and bison; Brucella
melitensis, which principally affects goats but is not present
in the United States; and Brucella abortus, which is the
most common cause of brucellosis and mainly affects cattle. In
cattle, the disease usually localizes in the reproductive organs or
the udder. Bacteria are shed in milk or leave the body with the
aborted fetus, the afterbirth, or with any discharges from the
reproductive tract. Brucellosis is commonly transmitted by direct
contact with infected animals. It is also transmitted to animals
that come into contact with a contaminated environment. Aborted
fetuses, placental membranes and/or fluids, and the vaginal
discharge that persists for several weeks after an animal has
aborted all carry the bacteria. The general rule is that
brucellosis is carried from one herd to another by an infected or
exposed animal. This occurs when a herd owner buys replacement
cattle that have been infected or exposed prior to purchase.
The incubation period in cattle is quite variable, ranging
from 2 weeks to 7 or 8 months or even longer. more... When
abortion is the first sign observed, the minimum incubation period
is about 30 days. Generally, cattle may be infected as calves but
not show any signs of infection until they abort. Infected animals
that don’t abort develop a positive reaction to the test
within 30-60 days after infection, although some may not develop a
positive reaction for several months.
There is no sure way to detect infected cattle by their
appearance. more... The most obvious signs in pregnant females are
abortion, birth of weak calves, and vaginal discharge. Not all
infected cows abort, but those that do usually abort between the
fifth and seventh month of pregnancy. Even though their calves may
appear healthy, infected cows continue to harbor and discharge
infectious organisms and should be regarded as dangerous because
they may not show any symptoms. Other signs include an apparent
lowering of fertility with poor conception rates and retained
afterbirths with resulting uterine infection.
Two primary surveillance procedures are used to locate infection without testing each animal in every herd, in addition to cattle tested for movement or change of ownership.more...
The primary surveillance method is a blood test from a sample of cattle more than two-years-old at slaughter (Market Cattle Identification [MCI] program). Numbered tags or backtags are placed on the shoulders of all cattle being marketed. Blood samples are collected at packing plants according to the National Brucellosis Surveillance Plan. If a sample reacts to the test, it is traced by the backtag number to the owner of the herd from which the animal originated. The owner is contacted by a State or Federal animal health official to arrange for an investigation that may involve testing the entire herd. The key to the MCI program is proper identification of all animals so they can be traced to their herds of origin. Backtags and other man-made identification devices are collected and sent to the State diagnostic laboratory along with matching blood samples to aid in identifying ownership of reactors.
The second surveillance method is a milk test called the Brucellosis Ring Test (BRT). It is conducted on cattle dairies twice a year by testing a small sample obtained from the creamery or farm milk tank for evidence of brucellosis. Milk from each cow in the herd is included in the sample taken for testing. All positive herds are investigated.
The disease may be avoided by employing effective
sanitation and management practices. more... Replacement animals
should be obtained from brucellosis free herds and free areas.
Cattle may be tested when purchased and retested after a 30-60 day
isolation period during which they are kept separate from the
remainder of the herd. This will allow detection of animals that
were in the incubation stage when acquired. Heifers may be
vaccinated when they are 4-6 months old. At this time a tattoo is
applied in the ear. Currently, there is a cooperative State-Federal
brucellosis eradication program to eliminate the disease from the
livestock population in the United States. Like other animal
disease eradication efforts, success of the program depends on the
participation of livestock producers. The program’s Uniform
Methods and Rules set forth the minimum standards for states to
achieve eradication. States are designated brucellosis free when no
cattle or bison are found to be infected for 12 consecutive months.
California has been brucellosis free since 1997.
Brucellosis in humans, known as undulant fever, usually
develops like influenza but persists for several weeks or
more. more... Farmers, ranchers, veterinarians, and packing plant
workers are among the hardest hit because they come into direct
contact with infected animals. The initial symptoms are fatigue and
headaches, followed by high fever, chills, drenching sweats, joint
pain, backache, and loss of weight and appetite. Death does not
occur frequently, but the disease is too serious to be dealt with
lightly. Rarely, if ever, does a human contract the disease from
another human. Only 77 cases of human brucellosis were reported in
the United States in 1990. There is no danger from eating cooked
meat products because normal cooking temperatures kill the
disease-causing bacteria. However, care should be taken when
consuming raw milk products, which may contain the bacteria.
Consumption of raw dairy products (those made from unpasteurized
milk) and contact with infected animals remain the major sources of
human infection with Brucellosis. People should take the precaution
of disinfecting areas likely to become infected and keeping them
clean. They should wear sturdy rubber or plastic gloves when
assisting cows calving or animals that abort, and scrub well with
soap and water afterwards. Prevention of cuts and the contamination
of cuts should be addressed, as well as avoidance of contamination
of the eyes with body fluids of animals. Exercise care in handling
and disposing of placenta, discharges or aborted fetuses and avoid
contact with tissues that could be infected.
Visit the CDC website for more information on brucellosis in people. www.cdc.gov/brucellosis/
Veterinarians must be licensed and accredited and have a valid contract with CDFA to vaccinate calves against brucellosis in California. To become a contract veterinarian, please contact your district office.
Instructions for Contract Veterinarians more...
Only female calves from four (4) through twelve (12) months of age are to be vaccinated under the terms of the contract. Each vaccinated calf must be identified by an official tattoo placed in the right ear. It is very important that a readable and lasting tattoo is produced in every calf vaccinated. Apply the tattoo after thoroughly cleaning and drying the correct area of the ear. In addition to the tattoo, all vaccinated calves should bear an official orange ear tag attached to the right ear.
Disinfect the tattoo applicator and equipment between calves and after vaccination is completed. Contaminated tattoo devices can spread diseases. Report vaccinated calves on AHB form 76-26 within 14 days. Give the original to the owner, send the pink copy to your AHB District Office, and keep the yellow copy in the book for your records. Tags, ink and forms can be requested from your District Office.
To order Brucellosis vaccine, a contract veterinarian may access the on-line system login page with a standard internet connection and browser at https://apps4.cdfa.ca.gov/brucvacc.The order placement will require entry of a valid credit or debit card number. If a veterinarian declines to pay for the Brucellosis vaccine using a credit or debit card, a check may be used. Be advised, purchases made using a check can take more than two weeks and shipments cannot be expedited.
- General Instructions for Contract Veterinarians
- Using the Online Brucellosis Vaccine Ordering System
- Brucellosis Vaccine Pricing Information
- Estimated Vaccine Delivery Schedule
- Unintentional Brucellosis abortus Vaccine Exposure Among Veterinarians