Its quite common in children unfortunately as there are a few outbreaks at the moment. You can tell they have it usually when they get sores on their mouth and sometimes on their body. They are like blisters and can be very irritating for them when its in their mouth. Its a virus, so I don’t think anti-biotics work on it. It lasts around a week and the best thing to do is keep them home and wrapped up and give them plenty of fluids. It will usually pass of its own accords – so rest & fluids best thing for it.
Hope your LO does not get it. My friends LO has it and is quite cranky with it.