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Viruses are tiny organisms that rely on human or animal cells for their survival, so they cannot last very long outside the body27. They cause illnesses by invading healthy cells and multiplying.

Bacteria are single cell organisms usually found in and on our bodies27. Some bacteria are harmless – and can even be good for us – and some cause infections27.

Viruses are tiny organisms that rely on human or animal cells for their survival, so they cannot last very long outside the body27. They cause illnesses by invading healthy cells and multiplying.

Bacteria are single cell organisms usually found in and on our bodies27. Some bacteria are harmless – and can even be good for us – and some cause infections27.