- Communicable diseases have a range of causes (pathogens)
- Pathogens may be viruses, bacteria, protists and fungi; they are microorganisms that cause infectious disease
- They can infect both plants and animals
- Bacteria – reproduce rapidly and can affect the host by releasing toxins, these damage tissues and make us feel unwell, (see Bacterial Diseases
- Viruses – need a host to survive and reproduce, (see Viral Diseases)
- Fungi – grow on living tissue, some are single-celled and others have a body made of hyphae, see (Fungal Diseases)
- Protists – eukaryotic organisms some of them are parasitic, that live on or inside the host organism. They are often transferred by vectors, (see Protists)
Pathogens can be spread by a range of transmission methods – you need to be able to explain how these are transmitted and some ways to prevent the transmission of these.
Remember that bacteria produce toxins that damage cells and viruses are replicated inside cells. This links to how antibiotics are effective against bacteria but not viruses (see Antibiotics and Painkillers).