Distinguishing between the myriad causes of intestinal symptoms such as abdominal pain, bloating, and persistent diarrhea can be challenging, especially in young patients. This case1 of a young woman with a history of multiple autoimmune disorders illustrates the challenges and potential pitfalls of incomplete differential diagnosis.
A white female, age 24, who reports persistent diarrhea is admitted for assessment of abdominal bloating accompanied by pain that she describes as unbearable. She has had the symptoms for the past 10 days. She is also nauseated but is not vomiting. Her temperature is normal and she has no diarrhea or other intestinal symptoms. The patient reports that she has not travelled recently, nor has she been in contact with anyone who was ill.
She reports having experienced episodes in the past that involved similar symptoms. During one such previous admission to another hospital, clinicians performed a computed tomography (CT) scan of the abdomen, but a colonoscopy was not performed. Based on the CT findings, the patient was diagnosed with Crohn’s disease.
Her medical history reveals that she was diagnosed with juvenile rheumatoid arthritis A, and has a history of chronic pericarditis and pulmonary arterial hypertension. She had also undergone cholecystectomy for kidney stones.
Investigation and Diagnosis
You have a CT abdomen scan and colonoscopy with fluid aspiration performed. Results of the CT scan indicate wall thickening with submucosal fat noted at the terminal ileum (Figure 1). Although the CT finding is non-specific, it is suggestive of chronic inflammation associated with an inflammatory bowel disease.
The ileal biopsy does not indicate any changes suggestive of inflammatory bowel disease. However, the colonoscopy identifies parasites in the transverse colon, the ascending colon, and in the cecum. Fluid sample analysis results are positive for the pinworm Enterobius vermicularis.
Further enquiries reveal that she lives in a forested area and that the area surrounding her house has been muddy due to recent rainy weather. She and her partner and children typically drink from a privately owned well, which has run dry on several occasions.
The physician reporting the case suggests that in the absence of the usual travel or ill contacts to explain the typical fecal-oral route, consumption of contaminated well water is the likely source of the pinworm infection.
Treatment and Follow-Up
The patient’s pain improves following treatment with one dose of the anti-helminthic agent, albendazole (Albenza). She is provided with a prescription and instructed to continue treatment for 2 weeks, and to ensure that her family members also receive treatment.
Although inflammatory bowel disease (IBD) is significantly less prevalent in the U.S. than Enterobius vermicularis infection, it may be better recognized. Crohn’s disease and ulcerative colitis, collectively identified as IBD, are generally among the differential diagnoses of young patients presenting with refractory diarrhea, after exclusion of other more common etiologies, notes the physician reporting the case.
Although not commonly seen in general practice or considered in differential diagnosis, enterobiasis is the most common helminthic infection in the U.S. and Western Europe, affecting about 40 million persons in the U.S.1 This is in contrast to IBD, which affects about 1.6 million Americans.2
Enterobius vermicularis infection often causes no symptoms beyond the characteristic perianal itching especially at night – however, as in this case, abdominal pain and diarrhea can occur.
Pinworm infection is usually relatively harmless and resolves within 4 to 6 weeks if there is no host autoinfection. However, in rare cases it can be associated with significant risks including appendicitis (accounting for up to 2.39% of cases in developing countries), intestinal obstruction, intestinal perforation, enterocolitis mimicking Crohn’s disease, and eosinophilic ileocolitis.3
Infection is usually diagnosed by microscopic visualization of Enterobius eggs, which are only evident in the stool of about 5% of those infected. A sample for microscopic examination can be collected as soon as the person wakes up using the “tape test”, which involves pressing the adhesive side of clear, transparent cellophane tape to the skin around the anus.4
Authors of a similar case report5 note that Enterobius vermicularis cannot penetrate the intestinal mucosa without some previous damage to the mucosal barrier. Suspected causative factors suggested in previous case reports include a perforated appendix6 and Campylobacter jejuni infection. In their case, which lacked evidence of a reasonable mechanism of mucosal damage, they suggested that the worms could cause ulceration by attaching themselves to the mucosa using their heads. While this may account for that patient’s subsequent invasive infection, the question remains unanswered.
The diagnosis of IBD is a serious label that requires biopsy confirmation before committing to possibly lifelong treatment and possible adverse effects, concluded Al-Saffar and colleagues. Even in the patient with classical presentation and imaging, unexpected conditions [including infection with intestinal parasites such as Enterobius infection] may preclude appropriate diagnosis and management. Thus, they wrote, even in an apparently typical patient presentation, inflammatory bowel disease should always be endoscopically confirmed and biopsy proven.
1. Al-Saffar F, et al “Pin Worms Presenting as Suspected Crohn’s Disease” Am J Case Rep 2015; 16: 737-739.
2. InflammatoryBowelDisease.net “What Is Crohn’s Disease: Statistics”
3. Yang C, Smith S. Parasites & Pestilence: Infectious Public Health Challenges. Stanford University 2007.
4. Kucik CJ, et al “Common intestinal parasites” Am Fam Physician 2004; 69(5): 1161–68.
5. Johansson J, et al “Pinworm Infestation Mimicking Crohns’ Disease” Case Rep Gastroint Med 2013; 10.1155/2013/706197.
6. McDonald GS, Hourihane DO “Ectopic Enterobius vermicularis” Gut 1972;13(8):621-626.
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