Is there any risk of illness from eating spinach?

Yes. Both loose and pre-packaged spinach may be contaminated with the pathogens E. coli  or salmonella, depending on how the spinach was farmed, harvested, or processed. Bacteria can be transferred from dirt residue or from anyone handling the spinach during harvesting, processing, or transport. Therefore, special care is required in storing, handling, or preparing spinach.
 
Like all fresh produce, spinach also is prone to spoilage. It is not advisable to eat spinach that smells sour or shows excessive yellowing or browning.
 
Source(s):
Medicine.net "Tips For Keeping Your Produce Safe"

Medicine.net "Learn to Wash Produce Properly"