How is the term contamination defined in connection with a communicable disease?

The definition of contamination in the context of a communicable disease specifically refers to the presence of pathogenic agents on a surface, article, or substance. This point serves as a crucial distinction, as contamination can occur without direct transmission of disease from person to person. It emphasizes that surfaces or objects can harbor pathogens, which can potentially lead to infection if they come into contact with a susceptible host. Contamination underlines the importance of hygiene practices, as reducing the contamination of surfaces can significantly curb the spread of communicable diseases.

In contrast, while the infection of an individual or animal does relate to the consequences of contamination (but does not define it), the focus is on the presence of pathogens rather than their impact on a host. The transfer of a vector is important for understanding transmission, but it does not specifically pertain to the concept of contamination itself. Lastly, contact between sources of infection implies interaction rather than the state of an environment or object being contaminated. Each of these other choices touches on aspects of disease transmission and infection dynamics but does not encapsulate the precise definition of contamination as effectively as the correct answer.