Brucellosis

What is brucellosis?

Brucellosis is an infectious disease caused by some bacteria in the Brucella genus. Symptoms can include fever, headache, weakness, profuse sweating, chills, weight loss, and general achiness. Infections of organs including the liver, spleen, and lining of the heart may also occur. People who have weakened immune systems, young children, pregnant people, or those with artificial heart valves are at higher risk of severe disease if they become infected.

There are four species of Brucella bacteria that cause most cases of brucellosis in the US:

Brucella melitensis and Brucella abortus are most common (about 75% of cases) and are mainly caused by consumption of unpasteurized dairy products in countries outside of the US.
Brucella suis causes about 25% of cases and is mostly associated with hunting feral swine or butchering swine carcasses.
Brucella canis very rarely causes disease in people and is transmitted by infected dogs.

In addition, a strain of Brucella abortus (RB51) found in the Brucella vaccine for livestock rarely causes human infection and is most often associated with veterinary needle-stick exposures while vaccinating cattle or raw milk consumption.

Where does it come from?

Brucellosis generally spreads to people from infected animals or animal products. Animals that most commonly get brucellosis include cattle, bison, elk, sheep, goats, pigs, cats, dogs, coyotes, deer, moose, and caribou but many other animal species can carry the bacteria. Washington was declared free of swine (pig) brucellosis in 1975 and of bovine (cow) brucellosis in 1988. Not all states in the US are free of swine brucellosis. Although the US is considered free of bovine brucellosis, occasional cases occur related to bison and elk in the Greater Yellowstone Area. Many other countries have endemic swine or bovine brucellosis. Cases of canine (dog) brucellosis are diagnosed each year in Washington state, mostly in animals adopted from out-of-state. Not all states in the US are free of swine brucellosis. Although the US is considered free of bovine brucellosis, occasional cases occur related to bison and elk in the Greater Yellowstone Area. Many other countries have endemic swine or bovine brucellosis.

How is it spread?

People can be infected by consuming unpasteurized milk and dairy products from infected cows, sheep and goats. People can also get infected when skin wounds are contaminated through contact with saliva, urine, blood, vaginal discharge, and infected animal tissues such as aborted fetuses or placenta. Because of this, veterinarians, hunters, slaughterhouse workers, and other people who work with animals are at higher risk of infection. Rarely, brucellosis can spread from family pets to people.

Inhalation of the bacteria is uncommon, but aerosolized bacteria can present a risk to laboratory workers who handle Brucella specimens or people who are present during animal slaughter or attending animal births. Person to person infection is unlikely. Brucella is a possible agent of bioterrorism.

What is the treatment?

A combination of antibiotics for at least six weeks is necessary.

How soon do symptoms appear?

Usually within 5 to 60 days of exposure, but up to several months.

How common is brucellosis?

Brucellosis in people is rare in the US. Most cases occur among people who have recently lived in or traveled to countries where brucellosis is common or in people who have ingested raw food products imported from abroad. Occasionally there are cases reported in veterinarians, butchers, rendering plant workers, meat inspectors, hunters, and farmers.

How can we prevent the spread of brucellosis?

The main way to prevent human brucellosis is by eliminating the disease in domestic animals. Cattle, dairy goats, and swine imported from other states are required to have a health certificate indicating that they are brucellosis-free. Consume only pasteurized milk or milk products, including during travel.

If adopting a dog from out of state or out of the country, ensure they have a valid health certificate. Dogs in breeding programs, stray dogs that have not been spayed or neutered, and unowned or free roaming dogs are at higher risk of having brucellosis and should be tested for Brucella canis prior to importation or adoption.

If working with birthing or whelping animals, wear personal protective equipment, including eye protection, disposable latex or rubber gloves, fitted N95 respirator, and protective clothing or disposable gown.

If working with animal carcasses, protect open wounds or abrasions with bandages and use protective clothing, gloves and goggles. Clean and disinfect surfaces that animal tissues or fluids touch and wash hands after handling animals or animal products. Do not harvest or handle wild animals that are sick or found dead (Washington deer or elk that are roadkill may be salvaged with a Washington Fish & Wildlife permit. Hunters should follow safe field dressing, handling, and cooking practices:

Wear eye protection and latex or rubber gloves when handling carcasses
Use clean, sharp knives for field dressing and butchering
Dress game in a well-ventilated area
Do not eat, drink, or smoke while cleaning game
Wash hands as soon as you can after butchering
Don’t feed raw meat or other parts of the carcass to any pets
Clean all tools and reusable gloves with a disinfectant, like 10% bleach
Thoroughly cook meat to an internal temperature of 165 degrees Fahrenheit before consuming

What should I do if I suspect someone in my family has brucellosis?

Contact your primary health care provider or call your local health department.

What should I do if my dog is diagnosed with brucellosis?

If your dog is displaying symptoms of brucellosis or has been diagnosed with brucellosis (Brucella canis), you should follow up with your veterinarian as soon as possible. A blood sample can be collected to test for the disease. Brucellosis in dogs is very difficult to treat, and dogs may still carry the infection even after treatment. Dogs infected with brucellosis must be isolated from other dogs for the life of the infected dog to prevent spreading the disease, or may be euthanized. Brucella canis infections in animals are reportable by veterinarians to the Washington State Department of Agriculture: https://fortress.wa.gov/agr/apps/rad/