Cause and Spread of Infection

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Cause and Spread of Infection 1. Understand the Causes of Infection 2.1 Identify the Differences Between Bacteria, Viruses, Fungi and Parasites Viruses are extremely small pieces of nucleic acid that are surrounded by a thin protein coat. They are different from other infectious microorganisms because they cannot replicate outside of a living host cell. They synthesize energy from their host cell and do not have a cell membrane, cell wall or cell nucleus. They have genes but lack a cellular structure. Bacteria are much larger than viruses and are shaped like spheres, spirals or rods. They are a single-celled organism and have a nucleus that lacks a membrane. They inhabit many habitats including soil, water, and waste. Sometimes they have symbiotic relationships with certain species. They can convert compounds such as methane into energy. Parasites can be protozoa, yeasts or multicellular organisms such as worms. They can live either on or in a host where they synthesize nourishment. They live on or in their host for an extended period of time. Fungi comes in many different forms, some of which we eat (such a yeast and mushrooms). Other forms include moulds. Some forms of fungi can cause serious harm to humans. 2.2 Identify Common Illnesses and Infections Caused by Bacteria, Viruses, Fungi and Parasites * Bacteria – Salmonella, E-coli, tetanus, typhoid fever, cholera * Virus – Aids, common cold, cold sores, influenza * Fungi – Athletes Foot, candidoses, ringworm * Parasites – Ticks, fleas, lungworm 2.3 Describe what is Meant by ‘Infection’ and ‘Colonisation’ Infection is the invasion of a living host’s bodily tissue by disease causing organisms that multiply in the body and cause illness. Colonization occurs when one organism or more populate an area. Bacteria colonize on an area of the body surface and do not cause
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