Brief Answer:
It can manifest in many forms. primary cause is unknown.

Detailed Answer:
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The primary cause of eosinophilic gastroenteritis is unknown. Patients with history of food allergies and asthma have relatively higher RJs for developing eosinophilic gastroenteritis.
The signs and symptoms varies among different patients.
The common presenting symptoms include non specific gastrointestinal symptoms like diarrhoea, vomiting, constipation, bleeding , abdominal distention. Some patients present with unexplained weight loss probably due to malabsorption.
Rarely it can present as gastric ulcer and cholangitis
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