Enterobius vermicularis infestation leading to Meckel's diverticulitis in an adolescent boy: An extremely rare presentation

Introduction

Enterobius vermicularis (pinworm) is an intestinal nematode affecting children worldwide. It is transmitted through feco-oral route. Following ingestion, the embryonated eggs hatch in small intestine, develop into adult worms and reside in the caecum, appendix, colon, and rectum. Adult worms mate in intestinal tract and gravid female worm lays eggs at night leading to nocturnal pruritus caused by an irritant mucous; shed with the eggs by the female.[1]

Meckel's diverticulum (M.D) is the most common congenital abnormality of the small intestine, presenting in 1%–4% of the general population. It is a remnant of the vitellointestinal duct which arises as a true diverticulum from the antimesenteric border of terminal ileum.[2] We hereby report a case of Meckel's diverticulitis due to E. vermicularis infestation.

Case Report

An 11-year-old boy presented to emergency with complaints of acute pain abdomen for the last 1 day. The pain was sudden in onset and severe in intensity. There were two episodes of vomiting in last 24 h. There were no urinary or bowel complaints. On examination, there was tachycardia (pulse rate 96/min), low-grade fever (38.6°C) and tenderness in the right iliac fossa. Emergency ultrasonography revealed probe tenderness at Mcburney's point along with inflamed gut loops in infraumbilical region. The patient was planned for emergency laparotomy with a provisional diagnosis of acute appendicitis. Intraoperatively, appendix measured 8 cm in length with congested serosal aspect. On further exploration, inflamed M.D was found measuring 6 cm in length, approximately two feet from ileocaecal junction. Meckel's diverticulectomy along with appendicectomy was done.

Laboratory investigations

Emergency investigations revealed leukocytosis (11.8 × 109/L). Absolute eosinophil count was 1.3 × 10⁹/L. Histopathological examination of appendiceal lumen had E. vermicularis infestation [Figure 1a]. M.D showed ulceration of the lining epithelium with trans-mural inflammation and necrosis [Figure 1b]. E. vermicularis ova were seen in wall of M.D [Figure 1b]. However, no adult worm was identified in the sections examined from M.D. Multiple sections from M.D were examined to rule out any heterotopic tissue. No worms/eggs or cysts were identified in stool examination or after the application of a transparent adhesive tape to the perianal area. The index case was treated with mebendazole 100 mg twice a day for 3 days. This course was repeated after 2 weeks. All the family members were also given empirical treatment for the infection.

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Figure 1

(a) Appendix lumen showing adult worms of Enterobious vermicularis. (b) Meckel's Diverticulum with ova of Enterobious vermicularis and transmural necrosis and inflammation

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The patient is on regular follow-up and is asymptomatic till date. Repeat stool examination was normal.

Discussion

Fabricus Hildanus described the appendiceal pinworm for the first time in 1634.[34] Since then, E. vermicularis is known as one of the most common intestinal nematode. The organism occurs more frequently in temperate and cold climates. Children are especially susceptible to the infection. The infection is transmitted by feco-oral route. Infrequent bathing, use of soiled underwears, crowded habitation, and lack of exposure to sunlight all favor disease transmission. E. vermicularis in the appendix is usually an innocent bystander and does not elicit an inflammatory response as seen in the particular case. E. vermicularis has rarely been reported at ectopic sites such as genitourinary tract, kidney, and eye.[345]

M.D is usually asymptomatic and detected incidentally during laparotomy. About 4%–6% of cases can have symptomatic presentation in the form of intestinal obstruction, bleeding, diverticulitis, and perforation. Meckel's diverticulitis with E. vermicularis infestation is an extremely rare clinical presentation. To the best of our knowledge, there is one case report of E. vermicularis infestation of the M.D five decades back.[6] Tseng and Yang reviewed clinical and diagnostic characteristics of M.D from 1988 to 2008. There were a total of 47 children and characterized as follows: bleeding (n = 21), obstruction (n = 12), diverticulitis (n = 12), and two diagnosed incidentally.[7] No case of parasitic infestation of M.D was found. No protective immunity against E. vermicularis infection develops, and re-infection is common. Environmental contamination with infective eggs is seen, so testing/treatment of household contacts should be considered. According to Centers for Disease Control and Prevention guidelines treatment of E. vermicularis is mebendazole 100 mg orally to be repeated after 2 weeks or pyrantel pamoate, given at a dose of 11 mg/kg body weight (to be repeated after 2 weeks).[8] This case was treated with mebendazole 100 mg twice a day for 3 days. This course was repeated after 2 weeks. Family members were treated empirically for the infection. General instructions for maintenance of adequate cleanliness and hygiene such as washing hands properly with soap and warm water after using the toilet, changing diapers, or before handling food items were given.

Conclusion

We report an extremely rare manifestation of E. vermicularis infection presenting as Meckel's diverticulitis. The identification of underlying pathology of Meckel's Diverticulitis as E. vermicularis infection is important as timely treatment of infected case and testing/treatment or recommendations of environmental cleaning can prevent reinfection or spread of infection to other household contacts and may ultimately avoid surgical intervention in family members too.