Bacteria is a single celled micoorganism that doesn’t need a living host/cell to reproduce, they collect their nutrition from their surroundings. As they are microorganisms they can only be seen under a microscope. A bacterium usually only affects one part of the body and usually doesn’t spread through or across the body. Bacterial infections can be treated with a course of antibiotics. There are 3 kinds of bacteria: Pathogenic Bacteria – these make you ill, when ingested in large quantities are responsible for the majority of food borne diseases or food poisoning. Not all of the bad bacteria is ingested, many can be inhaled, spread by in-direct or direct contact or are blood-borne. Spoilage Bacteria – this makes food decay, rot or perish. Sometimes it is easily recognised when there is spoilage bacteria present as the food may become mouldy, discoloured, smelly, slimy or soft. Micro-organism – these are mainly the good ones. Bacteria are microbes and they are found anywhere and everywhere, these living things can only be seen under a microscope. You’ve most likely heard of helpful bacteria and as you can probably tell, it will not cause you harm. Such as those that help digest foods and etc. It’s used to make medicinal drugs and even yoghurt and cheese. Fungus like to grow in places that are moist and warm. Certain types of fungi can be harmful and dangerous to our health, like bacteria and viruses some can act as pathogens. But some fungi can be beneficial to us such as the use of penicillin. Symptoms of fungal diseases can be as common as itching, wheezing, coughing, fever but they can be very serious and have the ability to cause death. Such as meningitis. Human fungal diseases can occur due to fungal toxins or infection. Parasites are organisms that need another organism for their survival. Some parasites make the host weak because they draw the host’s nourishment so they are able to survive, in some serious cases it can cause death. There are 3 types of parasites: Ectoparasite – which is a parasite that lives on the outside of the host, so examples of this is lice in various areas where there is hair and also small mites. Epiparasite – This one feeds on other parasites such as the Ectoparasites. These can be fleas or ticks. Endoparasites – this is one that lives inside the host, so therefore is the most dangerous as it affects the host more. Examples of these are tapeworm, flatworms and even heartworms. Virus is made up of different genes and proteins that spread throughout the body by invading the host’s cells so that they can then multiply and reproduce in the body. For viruses to be spread it needs to be direct contact, such as cold sores, kissing, or directly touching the lesion etc. Also viruses rarely ever respond to antibiotics due to their ability to mutate to form new strains which is incredibly difficult to then treat disease, as new strains may be resistant to known treatments.