When you read about eosinophilic esophagitis you may come across different abbreviations for this condition. Most commonly people refer to eosinophilic esophagitis as EE or EoE. However, now accepted abbreviation is EoE, since EE has been used by gastroenterologists for Erosive Esophagitis.
You may also see EO which is an abbreviation for Eosinophilic Oesophagitis which is the standard spelling in the UK, Australia, and New Zealand. Regardless of how it is referred (EE, EoE, EO, eosinophilic esophagitis, or eosinophilic oesophagitis), they are all referring to the same condition.