Imagine it’s wintertime. This is a time you or someone you know gets a cold. You cough and sneeze and feel terrible. Maybe you go to bed for a couple of days or keep going – just! What’s going on inside you at this time?

It’s a busy time for microorganisms. The pathogenic microorganisms (commonly called germs or bugs) have got past the first line of the body’s defence (skin, tears and mucus) and have entered the body. Your immune system kicks in and fights back to destroy the pathogens causing the infection.

Spreading infection

People transmit infection by spreading microorganisms (germs) from one person to another.

Some germs can be spread through the air (such as the common cold). Tiny water droplets loaded with microorganisms shoot out of our mouths and noses when we sneeze or cough. If these land on someone else and get into their eyes, nose or mouth, they can easily get infected with pathogenic microorganisms.

Other microorganisms are spread through physical contact. This can happen either directly from one person to another or by touching something that the infected person has also touched (a door handle or water bottle, for example).

Some places harbour more harmful bacteria and viruses than others. Watch out for places where there are lots of people, like cafeterias and classrooms, and for things that people touch a lot, like door handles, cell phones and computer keyboards. You should wash your hands more when in places that are potentially dangerous or when handling items that people are touching all the time.

Controlling infection

We have learned to control our environment to help prevent being infected by these pathogens, but this has only happened in recent years.

During the American Civil War (1861–1865), more soldiers died of infection than any other cause. This is where we learned about the importance of personal hygiene, like washing our hands with soap and water. We also learned about sanitation, disinfectants, antiseptics and vaccines.

Discovery of cures for pathogenic diseases began in 1928, when Alexander Fleming discovered penicillin (the mould that killed bacteria).

Vaccination (developed in the 1800s) is a way to prevent infection. District Health Boards recommend being vaccinated (immunised) against certain diseases to stop us catching them and infecting others.

Eating healthy food, keeping physically fit and getting enough sleep help to keep us healthy, which is important because that strengthens our immune systems to fight off pathogenic microorganisms.

Preventing infection

There are a number of simple steps you can take every day to help prevent spreading cold and flu viruses:

  • Wash and dry your hands often. Wash for at least 20 seconds using soap, which kills the germs.
  • Wash your hands before you eat, every time. This is to stop germs spreading to your food, which you then eat.
  • Use tissues for sneezing or coughing into and throw them away immediately.
  • If you don’t have a tissue, cough or sneeze into the crook of your arm so the germs are not sprayed out into the air for others to breathe in.
  • Avoid touching your eyes, nose and mouth to stop you spreading your germs when you touch other things.

Epidemics and pandemics

An epidemic is defined as a disease or health-related issue that is showing up in more cases than would normally be expected. A pandemic refers to a global spread of an illness or disease. Before scientists knew how viruses passed from one person to the next, many people died in pandemics. From 1918–1919, a flu pandemic known as the ‘Spanish flu’ killed between 50–100 million people across the world – that’s 2.5–5% of the total population of the world at that time!

    Published 2 November 2010