Which organism is Brucellosis caused by, according to the material?

• A. Brucella
• B. Escherichia coli
• C. Salmonella
• D. Listeria

Answer: (A)

Brucellosis is caused by Brucella bacteria. These small Gram-negative coccobacilli primarily infect livestock and can be transmitted to humans through contact with infected animals or by consuming unpasteurized dairy products. Specific Brucella species like Brucella melitensis, Brucella abortus, and Brucella suis are the classic agents. In people, brucellosis often presents with fever, night sweats, fatigue, and muscle or joint pain and has been historically called undulant fever due to its fluctuating fever pattern. Pasteurization of milk is effective at killing Brucella, which is why using pasteurized dairy products reduces the risk. The other organisms listed cause different diseases (foodborne illness through E. coli, Salmonella, or Listeria monocytogenes) and are not the agents behind brucellosis.