Entamoeba histolytica; the causative organism of amoebiasis, is a protozoan parasite which affects two main organ systems in human body: Gastrointestinal tract and the liver. Gastrointestinal involvement occurs as a result of ingestion of the cysts of the parasite from food or water contaminated with faeces. The cysts are digested in the intestinal lumen releasing trophozoites. The trophozoites reproduce by clonal expansion and subsequently form cysts which are excreted in the faeces to start a new cycle [1].
Amoebiasis may involve any part of the bowel, but it has a predilection for the cecum and ascending colon [2]. Presentation of the intestinal illnesses has a spectrum ranging from aymptomatic infection, symptomatic noninvasive infection, acute protocolitis (dysentery) to fulminant colitis with perforation [3]. The majority (90%) of humans harbouring Entamoeba histolytica, fall into the group of asymptomatic carriers and live normal life [1, 4]. Only in 6%-11% of patients with symptomatic infection [5], the most virulent host response to the amoebic infection occurs leading to fulminating reaction, that leads to necrotizing colitis and perforation, peritonitis, and death [4]. Such course of amoebiasis in the form of acute fulminant necrotizing amoebic colitis (FNAC) is rare and only a few such cases of have been reported in the literature [6].
Development of such fulminant course is found to be associated with various factors including male gender, age over 60 years, associated liver abscess, progressive abdominal pain, and signs of peritonitis, leukocytosis, hyponatremia, hypokalemia, and hypoalbuminemia [7]. FAC, in majority of cases has characteristic symptoms and signs such as severe abdominal distention and pain with peritoneal signs, sepsis with high fever, watery or bloody mucoid diarrhea and dehydration [8, 9]. Peritonitis develops either because of frank perforation or a slow leak through an extensively diseased bowel [4, 10].
Apart from its rarity, clinical significance of fulminant amoebiasis lies in the fact that the condition is difficult to diagnose and treat, and associated with a very high mortality rate [11]. Diagnosis is often confused with idiopathic inflammatory bowel disease resulting in erroneous administration of steroids. Colonoscopic appearance and colonic tissue biopsy are helpful in differentiating amoebiasis from other forms of colitis. Clinical symptoms, laboratory studies and X-ray findings are insufficient to make an accurate diagnosis [12, 13]. Conventional method of microscopic examination of stool is less sensitive (25% to 60%). Antigen detection both in the patient's stool and serum is more sensitive and specific method [14, 15]. Pathology of the invaded colonic tissue shows transmural inflammation widespread necrosis along with large numbers of amoebic trophozoites within the inflammatory exudates [16].
For acute amoebic colitis, once suspected, early diagnosis and aggressive supportive and antiamoebic treatment should be instituted. If fulminant colitis develops, the outcome is poor with mortality ranging from 55% to 87.5% [17], peritonitis being the commonest cause of death [18]. Early diagnosis and surgical treatment significantly decrease mortality [8, 9]. It has been stated that conservative surgery has no place in the management of acute FAC, and primary total resection is the treatment of choice [19]. Because there is a high risk of suture breakdown in tissue containing amoebae; a staged operation in the form of exteriorization of the proximal and distal transected ends, and bowel reconstruction 3-6 months later, is highly recommended for FNAC [20]. Also, in endemic areas, patients with severe and undiagnosed colitis should be treated presumptively with specific antiamoebic therapy until a diagnosis of amoebic colitis can be excluded [8, 9, 19].
