13. Has current or historical evidence of eosinophilic esophagitis (evidence may be based on the following: missing response to acid suppressive therapy, the presence of eosinophilia in histological probes of the esophageal mucosa, a normal pH profile of the distal esophagus, symptoms of dysphagia and food impaction). The exclusion of participants based on a predominance of the "typical" eosinophilic esophagitis symptoms only (as above) is considered acceptable. However, in participants with a predominance of "typical" symptoms and co-existing significant dysphagia and food impaction, the syndrome should be excluded by endoscopy with biopsy.