Why Do Humans Get Sick From Bacteria?

Bacteria are tiny creatures that live all around us. Sometimes, they get into our bodies and start multiplying quickly. When that happens, they can make us feel sick, like when you have a tummy ache or a sore throat. Our body fights back with its immune system, which tries to catch the bacteria and push them out. But if the bacteria are too strong, we might end up feeling really unwell.