What is a pathogen?

A pathogen is defined as a disease-causing microorganism. This includes various types of organisms such as bacteria, viruses, fungi, and protozoa that can lead to illness in humans, animals, or plants. In the context of water quality, the presence of pathogens in water can pose significant health risks, making it critical for water quality analysts to monitor and control these microorganisms to ensure safe drinking water and prevent waterborne diseases.

Understanding the role of pathogens in public health underscores the importance of water treatment processes aimed at eliminating these harmful organisms. In contrast, beneficial microorganisms contribute positively to ecosystems and health, nutrients are essential for the growth of plants and organisms but do not cause disease, and water treatment methods are procedures used to improve water quality, but they are not classified as pathogens. This distinction is crucial for anyone studying water quality and health impacts.