**1. Introduction**

Esophagitis is the swelling and irritation of the esophagus. Thus esophagitis refers to inflammation or injury to the esophageal mucosa. The esophagus is the tube that is used in swallowing and it connects the back of the throat to the stomach. There are many causes of esophagitis and essentially the presentation is similar which include retrosternal chest pain, heartburn, dysphagia or odynophagia [1, 2]. The most common cause of swelling and irritation of the esophagus is stomach acid that flows back into the esophagus, called gastroesophageal reflux, which can lead to erosive esophagitis. Other etiologies include radiation, infections, local injury caused by medications, pill esophagitis, and eosinophilic esophagitis (EoE) [3]. Patients with EoE may present with food impaction. If the esophagitis is severe and leads to strictures, fistulization, and perforation, patients may present with symptoms related to those entities.

In addition, infections can also cause swelling and irritation of the esophagus. Fungi, yeast, viruses, and bacteria can all set off the condition, called infectious esophagitis. Anyone can get it, but a person is more likely to develop it if their immune system is weakened [4].

The incidence of infectious esophagitis has become prevalent in immunocompromised patients with cancers and organ transplant because of their survival rates due to advances in medical practice and management techniques. The causative agent is normally *Candida albicans*. However, organisms like herpes simplex virus (HSV) and cytomegalovirus (CMV) have often been known to invade the esophagus. Patients with acquired immunodeficiency syndrome (AIDS) may develop more fulminant forms of fungal and viral esophagitis (including human immunodeficiency virus [HIV] esophagitis), accentuating the need for early diagnosis and treatment. The purpose of this chapter is to review the clinical manifestations, etiology, pathophysiology, histopathology, diagnosis, treatment/ management, prevention, prognosis and other healthcare issues of infectious esophagitis.
