Study grant not obtained; not moving forward with study at this time.

To prospectively determine the natural history of inflammation resolution following initiation of diet treatment and to optimize the diet treatment of patients with EoE through the use of a non-endoscopic tracking device, the esophageal string test (EST).

This is an adult and pediatric prospective, longitudinal study in which we will measure symptoms, QOL and inflammation at baseline and again at 2, 4 and 6 weeks after starting stand of care (SOC) four food elimination diet (FFED) (Aim 1). Newly or previously diagnosed patients with EoE with active disease who will be undergoing SOC FFED will be offered entry into the study by the PI's or their local co-investigators at each of their institutions. EoE patients who are in remission on SOC FFED from Aim 1 will be recruited to participate in this food reintroduction trial in Aim 2. Eligible subjects will undergo SOC sequential food reintroductions and during the food introduction, ESTs will be performed at 2 and 4 week intervals during a clinic visit. If inflammation is detected by the EST, this food will be eliminated from the diet for six weeks and a repeat EST will be administered at this time to assess inflammation. If inflammation has resolved based on EST results, food reintroduction will resume. If no inflammation is detected by the EST at the 4 week interval, a new food will be added. EST will be performed after each food reintroduction as outlined above. Based on known allergenic properties of these foods, the order of food reintroduction will be soy, eggs, wheat and milk.

Inclusion Criteria:

• Participant must be able to understand and provide informed consent
• Males and Females ≥7 years of age to 65 years of age
• Have diagnosis of EoE
• Have histologically confirmed active disease ≥15 eosinophils/hpf
• Symptomatic (have experienced symptoms within the last one months prior to enrollment).
• Female subjects of childbearing potential must have a negative pregnancy test upon study entry
• Female (and male) subjects with reproductive potential, must agree to use FDA approved methods of birth control for the duration of the study

Exclusion Criteria:

• Inability or unwillingness of a participant to give written informed consent or comply with study protocol
• Secondary causes of eosinophilia
• Pregnancy
• Immunodeficiency states
• Have participated in any investigative drug study within 6 weeks prior to study entry
• Unable to complete study procedures including endoscopy
• Luminal stricture identified <13mm which would prevent passage of the EST and prevent assessment of mucosal inflammation
• Past or current medical problems or findings from physical examination or laboratory testing that are not listed above, which, in the opinion of the investigator, may pose additional risks from participation in the study, may interfere with the participant's ability to comply with study requirements or that may impact the quality or interpretation of the data obtained from the study