Since the 1990’s an increasing number of diseases associated with the infiltration of eosinophilic cells, cells which are part of an allergic process, have been described in various segments of the intestinal tract. We are including the increasingly observed and most common of the syndromes, eosinophilic esophagitis, here, as many of the affected patients have accompanying allergies and as symptoms are caused by food ingestion.
Eosinophilic esophagitis is a chronic disease, associated with the presence of many eosinophilic immune cells in the esophagus.
These cells persist even after treatment with acid-blocking drugs. The cause of eosinophilic esophagitis is unknown, but is probably multifactorial with genetic, immunologic and environmental factors being significantly involved. There is an altered immune response to common proteins, with abnormal activation of different immune cells, such as eosinophils, mast cells and basophils. This long-term inflammation can lead to changes in esophageal function and stiffening and narrowing of the organ.
A causal link to specific allergies is difficult to establish, but over 50% of adult patients with eosinophilic gastrointestinal disease have allergies, such as food or respiratory tract allergies, elevated numbers of eosinophilic cells and blood IgE levels are common and frequently a reduction in symptoms is achieved following elimination of the main foods causing allergies. In children eosinophilic esophagitis is even more commonly associated with food allergies than in adults.
A subtype of eosinophilic esophagitis responds well to treatment with acid blockers (proton pump inhibitors), indicating some overlap with reflux disease.
Frequency in population and natural history
Eosinophilic esophagitis can occur at any age, is more common in men and in whites.
The prevalence is rising and is now estimated to be at 0.5-1 in 1000 persons, and eosinophilic esophagitis is the most common cause of food impaction (food getting stuck in esophagus).
There is evidence that EoE is more common in patients suffering from food-allergy, rhinitis, asthma or atopic dermatitis. It is a long-lasting disease, with potential long-term changes and malfunction of the esophagus.
Discomfort or pain during swallowing and food impaction are the main symptoms in adults, however reflux, chest pain and heartburn are also common.
Testing and diagnosis
The mainstay of testing both initially and to assess treatment responses is by endoscopy, as tissue samples need to be taken.
There are some visual clues to the diagnosis, but these are much less accurate than evaluation of the biopsies (criterion of at least 15 eosinophilic cells per microscope high power field). During the course of the disease, repeated endoscopies are necessary. Blood samples are currently not accurate in the diagnosis of eosinophilic esophagitis.
Because of the frequent response (around 40%) to proton pump inhibitors (acid blockers) these should always be tried first. Further treatment options are exclusion of the food most frequently implicated in allergies (such as cow’s milk protein, soy, wheat, egg, peanut, and seafood), or an amino acid– based elemental diet. However, due to the cumbersome nature of these diets, long-term compliance is often poor.
In adults, or in the absence of a dietary response in children, steroids are sprayed into the throat using asthma-inhalers and swallowed with good effects in over 70% of patients.
A specially prepared viscous solution of steroid also seems to be a useful treatment option. Long-term treatment is often necessary, as the disease frequently returns when treatment is discontinued. In certain cases the esophagus must be endoscopically widened (dilation) to allow passage of food. Frequent endoscopy and tissue sampling is necessary in the course of this disease.