A biological agent that causes disease or illness to its host.
This definition encompasses the key characteristics of a pathogen:
* Biological agent: Pathogens are living organisms or viruses, not inanimate objects.
* Causes disease or illness: They are capable of disrupting the normal functioning of their host and causing symptoms.
* Host: They infect and harm a living organism, which can be humans, animals, plants, or even other microorganisms.
Some examples of pathogens include:
* Bacteria: E. coli, Salmonella
* Viruses: Influenza, HIV, COVID-19
* Fungi: Candida albicans, Aspergillus fumigatus
* Parasites: Malaria, Tapeworms
It's important to note that not all microbes are pathogens. Many bacteria, fungi, and other organisms are beneficial or even essential for life.