What are the three main types of pathogens that can cause disease in a host organism?

A pathogen is a microorganism or other agent that can cause disease in a host organism. The three main types of pathogens are bacteria(Staphylococcus), viruses(coronavirus), and parasites(Plasmodium). Bacteria are single-celled organisms that can cause a wide range of infections. Viruses are non-living particles that can only replicate inside host cells. Parasites are organisms that live on or inside another organism, known as the host, and can cause disease.