Bacteria - these are single cell microorganism that come in many shapes and forms these can be ball, rod or spiral shaped. most bacteria's are not harmful and some can be helpful less than 1 percent of these are infectious which can multiply in the body leading to disease. They can produce toxins that can make someone very ill. bacteria can be spread by coughing, sneezing, surfaces and skin contact, bodily fluids e.g. blood and saliva or even sexual intercourse. Most bacteria apart from the sphere shape variety (cocci) move around with a aid of a tale or flagella, under correct conditions they can reproduce by dividing in two and can multiply into a large population very fast. If the environmental conditions don't suit the bacteria they can become dormant and refer to as spores they can develop a thick outer coating and await the appropriate change of conditions. some examples of bacterial infections can be, tuberculosis, chlamydia, bacterial meningitis, strep throat, some urine infections.
Viruses - these are tiny infections agents that have a simple structure, consisting of DNA or RNA within a protein capsule they can only replicate in the living cells of other organisms. Viruses are responsible for causing a variety of different disease such as influenza, common cough and cold, aids, chicken pox and shingles and measles. Viruses are spread in very similar ways as bacteria they can enter the body through vector such as a mosquito or a cut on the skin ingesting food or contaminated surfaces, bodily fluids or faeces, antibiotics designed to kill bacteria are ineffective against viruses.
Fungi - most fungi are harmless and we can eat quite a few of them included in the kingdom of fungi are mushrooms, moulds in blue or green cheese and yeast in bred. other types of fungi can lead to illness for example athletes foot, thrush, urine infections, ring worm. Fungi infections often affect the lungs, skin and nails some infections may also penetrate the body to affect organs and can cause whole body infections.
Parasites - these are organisms that live on or inside another organism and benefit by getting nutrients at the expense of their host. They often spend part of their life cycle living outside the host living inside food, soil, water or insects. They can invade you're body by eating contaminated food or drink, malaria is transmitted to humans via mosquitoes. Many parasites call you're intestinal tract home and are homeless. examples of diseases than parasites can cause are giardia, toxop, lasmosis, cryptosporidiosis. there are sever types or parasites that can effect humans such as rounds worm, tape worms, flukues, protozoa.