All disease is multifactorial.

• A. True
• B. False
• C. Sometimes
• D. Uncertain

Answer: (A)

Disease arises from multiple interacting factors, not a single cause. In epidemiology we consider how host, agent, and environment all shape whether disease occurs and how severe it is. An infectious illness, for example, requires exposure to a pathogen, but whether you get sick depends on your immune status, genetics, nutrition, age, and other exposures; the same exposure can affect people differently because these factors interact. For chronic diseases, genetic predisposition often combines with lifestyle and environmental factors—smoking, diet, physical activity, stress—to determine risk. Even when a single agent is necessary, the dose, route of exposure, and timing in the life course influence whether disease develops. Because of these interconnections, the prevailing view is that disease is multifactorial.