Mold in a dishwasher

[Ryan Judah]

We have a tenant that says her dishwasher has mold in it.  She said she has used bleach to take care of it but that it keeps coming back.  After checking things out, the dishwasher doesn't have a 'moldy' smell to it but she was shown where else to clean to help gunk from collecting.  

Today, we got an email from her stating 'I wanted to reach out and let you know both my daughter and I have been getting really sick recently and I am start in to put two and two together that it is the mold in the dishwasher. I need it to be replaced. I have consistently cleaned it out and it grows back and this is a serious health issue.'

How would you handle this?  Replace the dishwasher?  How do we know that the dishwasher is causing them to become ill?  She's been in the apartment since July.