The infectious diseases are caused by pathogenic microorganisms or substances produced by them. These microscopic beings can be made up of one or more cells or even be acellular.
- Bacteria: prokaryotic unicellular beings, without a nuclear membrane, causing diseases such as diphtheria, salmonellosis , pneumonia, tuberculosis, cholera and tetanus, among others.
Activity: Classification of bacteria by their shape.
Song: Yes, I know you are remembering the song "I am a bacterium".
- Fungi: Eukaryotic and heterotrophic unicellular or multicellular organisms. They live in different environments, such as:
- Saprophytic fungi: They live in humid places on dead organic matter.
- Parasitic fungi: They live inside or outside of other living beings, which they harm. They are disease-causing fungi.
- Symbiotic fungi: They live associated with algae, forming lichens.
Examples of diseases (mycoses) are fungal ringworm and candidiasis.
- Protozoa: They are eukaryotic unicellular organisms that live in water and some, in liquids such as blood. They are the cause of diseases such as malaria , malaria , and sleeping sickness .
- Viruses: They are not true living beings, as they are acellular. They are obligate parasites and always need to take advantage of a cell's structure and metabolism in order to reproduce. Some examples of diseases caused by viruses are rubella, chickenpox , measles , flu, and AIDS.