How is a pathogen defined?

A pathogen is specifically defined as a microorganism that has the ability to cause disease. This includes various types of organisms such as bacteria, viruses, fungi, and parasites that can invade a host organism, evade its immune responses, and lead to detrimental health effects. The term emphasizes the harmful potential of these microorganisms, which distinguishes them from others that may be harmless or beneficial.

For instance, while some microorganisms are essential to human health, aiding in digestion and contributing to the immune system, pathogens are those that disrupt normal physiological functions and can lead to infections and illnesses. Therefore, understanding pathogens is crucial for the study of microbiology, public health, and infectious diseases, making the correct identification and definition vital in scientific discussions and research.