Your spouse will likely have a reduced immunity from the chemotherapy, while you will suffer from reduced immunity due to sleep deprivation, poor nutrition, etc.
How to deal
Keep things germfree, as much as you can. If you have germ factories (i.e. small children) living with you, this can be an even more challenging task. But this does not mean sanitizing your house and living in a bubble with no outside contact.
Know that certain cancers and chemotherapies require even more attention to cleanliness than others, so be sure to ask your doctor how important this issue is for your spouse's particular situation.
Often your spouse's physical comfort will suffer because of the effects of treatment. Many of these issues can be moderated, if you know what to do.
Sleeping can be painful due to surgery, intestinal issues, etc.
Find softer, less constricting clothing for your spouse.
Cancer treatments and their side effects can drastically affect how your spouse gets around the house and the world outside. Fatigue, anemia and low blood pressure can all have a profound effect on a person's ability to move around the house and navigate around objects on the floor.
Set up a second or pseudo bedroom in the living room or in front of the TV. It helps to have a place where your spouse can easily rest and relax, but still feel like he/she is participating in family activities and not feel alone.