With the lack of other symptoms I don't worry about fever too much as long as the child does not need medication. If they do then they need to be home. A child will run a low grade fever for lots of reasons including overtired, stress, teething, etc. and yes it can be the body's way of fighting off an infection before it gets a strong hold. A healthy child will run a fever to fight off a cold or whatever. When other symptoms appear like cough, runny nose or rash it means they have lost the battle and are considered sick.

Mistake was accepting the child with the rash. When the child showed up with the rash - first the parent had the nerve but she should have been sent to the clinic at that point to get the rash evaluated and pronounced safe - with results in writing. The doctor would likely have diagnosed the disease. If the doctor had said yes from the MMR then well you have your answer although that means the child has a mild form of the measles and I have heard from some that if they do get the rash they are contagious but not sure.

I would rething closing the daycare. You already have one child out with the disease and now your son makes the second. Chances are by tomorrow there will be more. I would stay open and give parents the option of keeping their child at home at no charge or bringing them as regular since they have already been exposed. The mom who started it doesn't have a choice she can't bring her child - I would do that out of spite and anger. Also if your son is old enough to be in school he is old enough to understand that he needs to play separate from the other children for a couple days.

In most areas you are supposed to contact your local health association to report an outbreak of a disease in your daycare and they would give the information about whether to close or not and what to do such as what and how to sanitize as well as how long to be closed.

The down side to closing is that all it does is expose other people to the disease since the other kids in care are now exposed and in the period of contagiousness if they have gotten it. Which means there is no point in a parent having back up care since no one wants the child. Yes the parent should take the time off but not everyone can do it without putting in for a personal day and you don't do that overnight. It has to be approved if you even have personal days at all.