Which term describes an object that causes disease?

The term that describes an object or factor that causes disease is "agent." In the context of epidemiology, an agent is any factor, whether it is a microorganism (like bacteria or viruses), chemical, or physical irritant, that can lead to an infectious or non-infectious disease. Understanding the role of agents is crucial in public health as it helps to identify how diseases spread and can be mitigated.

In contrast, the host refers to an organism that harbors a disease or pathogen, typically serving as the environment in which the agent can live and thrive. The environment encompasses the external factors affecting the agent and host interaction, including social, economic, and physical aspects that influence disease dynamics. A vector, such as mosquitoes or ticks, is a living organism that can transmit an infectious agent from one host to another, playing a key role in the continuation of the disease cycle but is distinct from the agent itself.