Tuberculosis (TB) is an example of a disease which is caused by pathogenic bacteria. It is a condition which affects the lungs and it is cause by a bacterium called mycobacterium tuberculosis. TB Most commonly affects the lungs, however it has also been known to affects other parts of the body, such as lymph nodes, bones, joints and kidneys. In some cases it can also cause meningitis (a disease (caused by the organism Neisseria meningitides) which causes an inflammation of the lining of brain). With effective treatment of 3-4 antibiotics for a period of six months (or more depending on the severity) it is possible to make a full recovery. TB is a localised disease. (Stretch.B, Whitehouse.B, 2007)
Viruses are a whole lot smaller than bacteria and can only be seen with a powerful electron microscope. Viruses differ from bacteria, because in order for a virus to cause a disease, they have to enter a living ‘host’ cell, whereas in bacteria only need to multiply until there is a reasonable amount to cause a disease. The virus changes the genetic coding of the host by releasing its DNA (deoxyribonucleic acid) or its RNA (ribonucleic acid). This eventually causes the viral coding to separate from the host cells and reproduce in other cells, the host then dies and the new virus is then released to find more host cells. A virus also does not have any metabolic activity therefore they cannot produce any waste. (P.Ayling,2007)
Mumps is an example of a localised virus (commonly a paramyxovirus) that causes swelling and tenderness of the salivary glands. It is transmitted through airborne contaminated droplets from coughs and sneezes of those who are infected. It can leave a person contagious for approximately five days and it usually affects children between the ages if 5 and 14 but in some cases it can also affect adults. (www.nhs.uk)
Fungi are plant-organisms that feed off other organisms in order to survive. They include yeasts, moulds, mildews, toadstools and mushrooms. They reproduce via spores that cause them to grow into fungi, when environmental conditions become better for them (for example, warm and moist temperatures). Mould starts to appear on food, as soon as it starts to age, it doesn’t cause food poisoning, however it can cause the food to start tasting foul. Its normal target is bread, oranges, lemons, cakes and cheese and appears to be white, green or black furry deposits. (Ayling.P, 2007)
Thrush is an example of a localised fungal infection and it is normally experienced as an infection of the vagina. It is caused by the fungus Candida albicans and it can be spread by sexual intercourse. In males, the fungus on the penis is called balaitis and it is characterised by white itchy spots, however it is easy to treat. (Ayling.P, 2007)
Parasites are plants or animals that live, grow and feed on or in other living organisms. The simplest type of parasite is a small single-celled life form called protozoa. They are usually smaller than their host and they are dependant on their host to survive. Parasites are known to affect most life forms, these include, bacteria infected by viruses (known as bacteriophages) and also humans who are exposed to over 100 parasites that are known to cause disease. They attack the human body by the hatching of larvae or laying eggs on the skin or hair or even the intestine. (Michie.V, Baker.L, 2008).
Fleas or Ctenocephalides, is a kind of parasite which feeds off blood. They are tiny insects that lay their eggs in narrow cracks or on animal fur until they hatch and start sucking blood to keep alive. They are not thought to transmit any serious illness to humans however they can cause severe irritation and a feeling of discomfort. Hygiene is essential if you want to get rid of them. (Ayling.P, 2007) (Michie.V, Baker.L, 2008).
Normal floras are micro-organisms which provide protection for the body and do it no harm. There presence is very important in prevention pathogens from colonizing the skin or the intestines. This is because the pathogens prefer to grow where there are no other organisms to compete with.
Transient floras are organisms that easily transferable to another person or surface, for example by salmonella found on raw meat, can remain on the hands for a long period of time, which increases the risk of cross-contamination. (Ayling.P, 2007)
There are different stages by which transient floras succeed in causing infection are termed the chain of infection. The main purpose for this chain is to show how pathogens move from one host to the next. This chain has to broken in order to prevent. (Ayling.P, 2007)
Below is a diagram of the chain of infection;
( http://faculty.ccc.edu/tr-infectioncontrol/images/chain.jpg)