Make sure that the litter is free of feces and generally dry. Litter boxes should be accessable and in a safe place. In multiple cat households, you may need to provide multiple litter boxes. Curiosity really can kill the cat, so closing doors, windows, boxes, and lids is a necessary precaution to keep a cat away from potential hazards. The most serious health hazard for humans is rabies.
Toxoplasmosis is caused by a parasite in cat feces, can be serious to pregnant women.
Be sure to discuss this issue with your doctor. Always keep sensible hygeine rules to prevent infection.