Description
Infectious diseases are illnesses triggered by a range of pathogenic microorganisms such as viruses, bacteria, protozoans, fungi, and parasites. These ailments can spread through animals, humans, insects, or other carriers.
The agents of infection are ubiquitous, varying in form and structure. They can be classified according to certain shared traits and include single-celled organisms like fungi, bacteria, and viruses. Diseases can also be caused by more complex, multicellular organisms, like worms.