Which epidemiology causation model has an inner core of genetic information?

• A. Wheel
• B. Chain of infection
• C. Epidemiologic triangle
• D. Web of infection

Answer: (A)

In the Wheel model, the pathogen’s genetic information sits at the center, showing that the agent’s inherent biology is the anchor for whether an infection can occur. The central core represents the agent’s characteristics—its genetics, virulence factors, and infectious properties—which drive the potential for transmission and disease. Surrounding rings capture host factors, environmental conditions, time, and other influences, illustrating how these elements interact with the agent but do not override the agent’s intrinsic biology. This central placement of the agent’s genetics is what distinguishes the Wheel model from the others: the chain of infection outlines sequential steps, the epidemiologic triangle emphasizes three interrelated factors, and the web of infection depicts a network without a single central core.