Brucella abortus, B. canis, B. melitensis, B. suis , whose identifications correlate with their reservoirs, respectively, cattle, dogs, goats and sheep, and pigs. These animals, and also horses, can be infected.
Susceptible wildlife are reindeer, elk, caribou, deer, otter, coyotes and bison.
Airborne transmittal has also been confirmed. Brucellosis occurs worldwide and is, generally speaking, under-reported. Vaccines, using either killed or live bacteria, are available, but are not often used to control large outbreaks because of the cost, and are not recommended for use in areas where the disease has been eradicated. Due to the economic impacts of spontaneous abortion by infected pregnant cows and reduced milk production, brucellosis has been singled out as a potential weapon in a mission for operatives intent on disrupting an agro-industry. And because the disease can be transmitted between wild and farmed animals, its appearance in areas where these species intermix has caused clashes between ranchers and conservationists.