Brucellosis Updates and Information

In cattle, the disease usually localizes in the reproductive organs and the udder. Bacteria are shed in milk or leave the body with the aborted fetus, placenta, or with any discharges from the reproductive tract of an infected animal. Brucellosis is commonly transmitted by direct contact, but can also be 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. A herd owner buying replacement cattle that have been infected or exposed prior to purchase can transmit the disease between herds.

A national eradication program has left most of the U.S. free of bovine brucellosis; however, a reservoir remains in the Greater Yellowstone Area, particularly in elk and bison, and spillover transmission does occur to domestic cattle herds.

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 can continue to harbor and discharge infectious organisms. Other signs include an apparent lowering of fertility with poor conception rates, retained placenta with resulting uterine infection, and decreased lactation.

The primary surveillance method is a blood test from a sample of cattle more than two-years-old at slaughter (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 a diagnostic laboratory along with matching blood samples to aid in identifying ownership of reactors.

A second surveillance method is a screening milk test called the BRT. If there is suspicion from a live animal or slaughter sample test, a small sample obtained from the creamery or farm milk tank can be tested 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 final surveillance method is a blood sample taken from a live animal by an accredited veterinarian for the purpose of private sales, change of ownership, interstate movement, herd certification or show, at the expense of the owner. Brucellosis testing must be done at a CDFA or USDA approved laboratory.

The disease may be avoided by employing effective sanitation and management practices. 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 (although infected heifers may not test positive until after they abort/calve). Heifers may be vaccinated when they are 4-12 months old. At this time, a tattoo is applied in the right ear – official identification must be applied at the time of vaccination if none is existing.

Only 115 cases of human brucellosis were reported in the U.S. in 2010 (CDC Brucellosis Surveillance). California had the highest number of reported cases that year (26). Primary sources of human infection are occupational exposure (farmers, ranches, veterinarians, packing plant workers, etc.) and consumption of imported unpasteurized dairy products; people also may become infected during travel to countries where disease is more prevalent. There is no danger from eating cooked meat or properly pasteurized dairy products because normal cooking temperatures kill the disease-causing bacteria.

Consuming only pasteurized dairy products can reduce the likelihood of infection. People handling or exposed to livestock can prevent infection and spread by disinfecting areas likely to become contaminated and keeping them clean (e.g. animal maternity pens and equipment), wearing appropriate personal protective equipment such as sturdy rubber or plastic gloves when assisting cows calving or animals that abort, and scrubbing well with soap and water after all contact with animals. Practices to prevent cuts and contamination of cuts and eyes with bodily fluids of animals are recommended. 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/

Additional Resources:

• Use of RFID as Official Identification for Brucellosis Vaccination
• Unintentional B. abortus Vaccine Exposure Among Veterinarians in MT, WY, ID

Ordering Brucellosis Vaccine

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.

• Using the Online Brucellosis Vaccine Ordering System
• Brucellosis Vaccine Pricing Information
• Estimated Vaccine Delivery Schedule