1.1 Bacteria are single cell organisms that cause infections, there are both good bacteria for example which lives in the gut , helping break down nutrients for the bodies needs as well as bad bacteria which can cause infections. They can produce toxins which are poisonous, and in optimum circumstances can multiply every 10-20 minutes via binary fission, so potentially millions can be produced within a short space of time if unchecked. They are usually untreated via antibiotics although new strains are becoming resistant to these drugs and stronger drugs and alternative therapies are now being developed and used to treat them.
Viruses are smaller than bacteria and cannot live independently, it needs a host cell to enable it to replicate. Viruses are immune to antibiotics and can lead to very serious illness and deadly disease.
Fungi are spore producing organisms such as yeast or mould, it re-produces via spreading spores and absorbs nutrients from any organic matter, they can cause disease especially in immune suppressed people, however from mould penicillin was developed, helping treat many illnesses effectively.
Parasites are organisms that live in or on the body. They live and feed on the host and can cause infection and spread disease directly. Some can be treated easily with creams/medication others can prove harder to identify and treat as they are different the world over, depending on where you are/climate/flora and fauna.
1.2 common illnesses relating to the above;
Bacteria – MRSA, salmonella, meningitis, pneumonia
Virus – colds/flu, AIDS/HIV, chicken pox
Fungi – Athletes foot, Thrush, Ringworm
Parasites – Lice, Scabies, Fleas
1.3 Infection is defined as an invasion of the body by pathogenic micro-organisms which then multiply and produce contamination or disease. Colonisation is where micro-organisms establish within/on a particular part of the body but do not cause infection. You can show no signs or symptoms but still be able to infect others. 1.4 Systemic infection is where infection is spread throughout the body probably via lymph fluids of bloodstream and can affect the whole or several organs. Localised infections are when the infection is confined to one are, usually the point if entry.