What is an infectious disease?

An infectious disease is defined as a condition caused by pathogenic microorganisms, such as bacteria, viruses, parasites, or fungi, that can spread from one individual to another through various routes, often referred to as the chain of infection. This chain includes the infectious agent, the reservoir, the portal of exit, the mode of transmission, the portal of entry, and a susceptible host.

Understanding that infectious diseases can be transmitted between individuals underscores the importance of infection control measures, particularly in healthcare settings like dental practices. These measures are crucial to prevent the spread of infections, protect patients and staff, and minimize outbreaks.

The other options do not accurately describe infectious diseases. A disease that is not contagious does not qualify as infectious since it does not involve transmission from person to person. Similarly, stating that a disease can be cured easily does not define its infectious nature, as the complexity of treatment does not determine whether a disease is infectious. Lastly, a disease only affecting animals would be categorized as a zoonotic disease, but it does not encompass the broader scope of human infectious diseases. Thus, option C clearly encapsulates the essence of what defines an infectious disease.