Do you know that mold is harmful to your health? I bet you did, but do you know why? For most people this is a harder question to answer. The reason mold is harmful to your health is as mold grows it releases spores into the air that are toxic to humans. They release spores in order to propagate. So the mold you see on your wall is not actually the mold that is harming you. It is the invisible spores floating in the air that will cause serious health issues. These health issues can be fatal, especially with children and the elderly.
In order to grow mold needs moisture, oxygen, food and a growing surface. In a home these things are pretty easy to come by, especially in a basement. Once mold is growing in your home it can be transferred throughout the house by your ventilation system.
So the best thing to do when you see mold is to get it checked by a professional. Wiping it with a disinfectant is not good enough to protect you from potential illness. A mold specialist will have to take samples and have them examined at a lab. What they are looking for is actively growing mold.
No house will have zero mold spores, but there is a big difference between a few mold spores and an actively growing mold infiltration. In order to find this information an air sample will normally be taken inside and outside. The outside will give a baseline (or normal) mold count, and the inside will tell the specialist how safe your home is.
If you see mold, get it tested. The testing is not intrusive, and it could save you and your family from serious health issues.