How do humans most likely acquire Brucella spp. infections?

Brucella spp. infections are primarily associated with the consumption of unpasteurized milk products. The bacteria can thrive in raw milk from infected animals, such as cows, goats, and sheep. When humans consume these products, they are at risk of ingesting the bacteria, leading to brucellosis, which is characterized by flu-like symptoms and can have serious health implications.

The unpasteurized products provide an ideal environment for the bacteria to survive, making this route of transmission a significant concern in regions where brucellosis is endemic. Pasteurization effectively eliminates Brucella spp. from milk, which is why consuming pasteurized products is a key preventive measure against the infection. Understanding this route emphasizes the importance of food safety and public health initiatives in reducing the incidence of brucellosis in susceptible populations.

Other routes of transmission, such as breathing contaminated air, direct contact with infected animals, or insect bites, either play a minor role or are not considered significant transmission methods for Brucella spp. This detail helps clarify why the correct answer revolves around the consumption of unpasteurized milk products.