How do humans commonly acquire Brucella infection?

Introduction:
Brucellosis is a classic occupational and food-borne zoonosis. Understanding transmission routes informs prevention strategies.

Given Data / Assumptions:

• Possible exposures include food, direct animal contact, and dairy products.
• Human-to-human spread is exceedingly rare.

Concept / Approach:
Brucella infects via ingestion (unpasteurized milk/dairy, undercooked meat), direct inoculation through cuts or mucosa during animal handling, and less often via aerosols in laboratory settings. Combined, these make multiple routes viable.

Step-by-Step Solution:
Recognize food-borne risk: unpasteurized milk and contaminated meat. Acknowledge occupational risk: direct contact with animal tissues. Choose the inclusive answer covering major routes.

Verification / Alternative check:
Epidemiologic data consistently implicate all listed routes except routine person-to-person spread.

Why Other Options Are Wrong:

• Each single route alone: Incomplete; multiple routes cause infection.
• Airborne person-to-person spread: Not a common route for brucellosis.

Common Pitfalls:
Overlooking unpasteurized dairy as a key exposure; ignoring occupational hazards in abattoirs/vets.

Final Answer:
All of these routes (meat, direct contact, infected milk) can transmit Brucella to humans.