How Infections Spread
The best way to prevent infection is to prevent the microorganisms from reaching the body in the first place. There are many simple things that can be done to reduce the chance of passing on infections, or preventing catching them in the first place.
To stop all microorganisms being transferred, however, is very hard to do! Even the simplest actions of opening a door, or touching an object can cause contamination. Great care has to be taken in food production or medical environments to prevent contamination like this.
The video below shows how easy it is to transfer microorganisms from person to person.
Sources of infection include:-
Coughing or sneezing can release millions of microorganisms into the air, which can then enter another person.
Contaminated food or water can cause infection when ingested.
Bodily fluid contact can cause infections in the bodily fluid to be transferred between people.
Animal vectors can cause infections, for example insect bites can transfer microorganisms.
The video below shows the different routes that Infections can take to spread between people and across the planet.
Reducing the Chance of Infection
There are several simple ways to reduce the chance of Infection:-
Cover mouth and nose with a disposable tissue when coughing or sneezing, then throwing it away in a bin.
If ill, take time off school / work to prevent infecting others.
Ensure food is cooked properly, and don't share utensils.
Practice good personal hygiene.
Personal hygiene plays a huge role in reducing infection. By simply washing your hands properly on a regular basis, the chance of infection can be greatly reduced. However, most people do not wash their hands properly. The image below show how to wash hands effectively:-
The Body's Immune System
The human body works very well at protecting itself from infection. The body has several systems that prevent microorganisms from entering the body, or if that doesn't work, destroying them once inside.
The body protects itself from infection in three main ways:-
The skin - Acts as a barrier to stop microorganisms entering the body.
Mucus - Acts by trapping microorganisms in sticky fluid which stops them from reaching the body's cells.
White blood cells - Act in several ways to destroy microorganisms within the body.
White Blood Cells
White blood cells are the main defence against infection once it is within the body. The diagram below shows the two basic types of white blood cell:-
Each type fights Infection in a different way:-
Phagocyte - This type of white blood cell can change shape to engulf microorganisms, which are then digested.
Lymphocyte - This type of white blood cell creates antibodies, chemicals which attack a single type of microorganism only.
As seen above, some types of white blood cell create antibodies. Antibodies are chemicals which will target only one type of microorganism and no other. Antibodies are the reason that we develop immunity to an infection.
The process of developing immunity is:-
An infection enters the body.
The infection causes the body to become ill.
The white blood cells eventually learn to fight the infection and create antibodies to destroy it.
After the body is no longer infected, the antibodies stay in the bloodstream.
If the infection enters the body again, the antibodies are already there and the body won't become ill.
This is why once a person gets an infection such as Chicken Pox, it is unlikely to be caught twice.
Vaccinations are a very modern way of preventing infections. They work by letting the body's immune system learn to fight an infection without getting ill in the first place.
Vaccinations work by using either a weakened or dead version of a microorganism. This lets the body's immune system learn how to make antibodies to fight the microorganism, but because the microorganism is weakened or dead, the body doesn't become ill. These antibodies stay in the blood and will attack live versions of the microorganism, if the body does become infected, without making the body ill.
The video below shows a summary of how vaccines work to prevent people becoming ill.
Case Study - Cholera
Cholera is a bacterial infection that can be caused by drinking contaminated water, or eating contaminated food. Cholera causes severe diarrhoea, stomach cramps and nausea and kills over 140,000 people a year worldwide. Cholera kills due to the severe vomiting and diarrhoea causes the infected person to become severely dehydrated, which can be fatal if not treated.
The treatment for Cholera is Oral Rehydration Solutions. These are solutions that contain a mixture of Glucose (sugar) and salts, which when drank acts to replace the fluids and minerals lost due to Cholera. This allows the body enough time to fight off the infection itself.
The spread of Cholera can be prevented by:-
Boiling or sterilising water before drinking or cooking with it.
Avoid uncooked vegetables unless they have been prepared in safe water.
Good Personal Hygiene, washing hands is vital.
The video below shows a short animation that shows the effects of Cholera, as well as treatment and prevention.