Pathogens are classified based on their biological nature: 1. Bacteria: Single-celled organisms that can cause diseases such as tuberculosis and strep throat. 2. Viruses: Tiny infectious agents that replicate only inside the living cells of an organism, like HIV and influenza. 3. Fungi: Include yeasts and molds that can cause infections such as athlete’s foot and histoplasmosis. 4. Parasites: Organisms that live on or in a host organism and cause diseases like malaria and giardiasis.
