What We Need to Know About Infections?

1.1 Identify the differences between bacteria, viruses, fungi and parasites.

Bacteria are microbes with a single cell. There is no nucleus or membrane within bacteria, making its structure simpler than that of other organisms. Instead, the genetic information is contained in a single loop of DNA. Viruses are microscopic organisms consisting of genetic material surrounded by proteins, lipids, or glycoprotein coats. Fungi can be multicellular or single celled organisms. They can be found in almost any habitat but most live on land.

A group of fungi called the decomposers grow in the soil and play an important role in the cycling of carbon and other elements. A Parasite is an organism that lives within another organism (the host). It is dependant on the host for its survival as it cannot live independently.

1.2 Identify common illnesses and infections caused by bacteria, viruses, fungi and parasites.

Common illnesses and infections caused by bacteria, viruses, fungi and parasites are:

Bacteria: Salmonella, tuberculosis, MRSA, food poisoning, tonsillitis
Viruses: Common cold, warts, AIDS/HIV
Fungi: Athletes foot, yeast infection, ring worm
Parasites: worms, malaria

1.3 Describe what is meant by 'infection' and 'colonisation'

Infection is the invasion and multiplication of microorganisms that are not normally present within the body. An infection tends to show symptoms and may spread through the whole of the body. Colonisation is when germs are within the body, but do not make the person sick. People who are colonised will have no signs or symptoms and they can feel fine.

1.4 Explain what is meant by 'systematic infection' and 'localised infection'

A systematic infection is an infection that is spread throughout the 'systems' of the body, usually by the bloodstream.

This doesn’t mean the infection is more severe than a local infection, it just affects a larger proportion of the body. A localised infection is an infection that is restricted to one small area of the body only. It is possible however for a localised infection to spread and become a systematic infection.

1.5 Identify poor practices that may lead to the spread of infection.

Poor practices that may lead to the spread of infection are:

not wearing PPE
not washing your hands
not covering your mouth when sneezing or coughing
not storing or cooking food correctly
not cleaning surfaces correctly

2.1 Explain the conditions needed for the growth of micro-organisms.

In order to grow, micro-organisms require certain conditions. For example, they must have a supply of water, mineral elements and gas, such as oxygen. A physical requirement needed for the growth of micro-organisms is temperature. Each species of micro-organisms have a minimum and a maximum growth temperature range. This allows the optimum growth of the micro-organism. Another physical requirement is the pH of the environment the micro-organism is in. For most micro-organisms, the optimum pH is between 6.5 and 7.5.

2.2 Explain the ways an infective agent may enter the body

One way an infective agent may enter the body is through the respiratory system. These infective agents can enter the body through the nose and then start multiplying. An example of this is the common cold. Another way an infective agent may enter the body is through the digestive system. These infective agents can enter the body through the mouth and can make a person feel sick when the body starts trying to digest the food. An example of this is food poisoning, from food that hasn’t been prepared correctly. An infective agent can enter the body by penetrating the skin. An example of this is tetanus. Another way infective agents may enter the body is via sexual transmission. The infected bodily fluid can enter the body and multiply. An example of this is HIV. An infective agent can also be transferred from a mother to a child in the womb. An example of this is rubella.

2.3 Identify common sources of infection

Common sources of infection are:
food
poor living conditions
water
animals
people who are sick

2.4 Explain how infective agents can be transmitted to a person

A way in which infective agents can be transmitted to a person is by direct physical contact, for example by touching an infected person. Another way an infective agent may be transmitted to another person is through droplet contact. This happens by coughing or sneezing on another person. Infective agents can also be transmitted by the micro-organism being in the air for long periods.

2.5 Identify the key factors that will make it more likely that infection will occur.

Key factors that will make it more likely that infection will occur are: poor immune system
poor cleanliness and hygiene
handling bodily fluids
exposure to infectious environments