Enterobius vermicularis and its role in paediatric appendicitis: protection or predisposition?

BACKGROUND: E nterobius vermicularis is one of the most common parasitic infections of the gastrointestinal tract, and has been shown to infest up to 28% of children worldwide. The role of E . vermicularis in acute appendicitis has previously been questioned, with some studies identifying infection as a precursor for inflammation of the appendix, with others refuting such a link.
METHODS: A retrospective review was conducted of all appendices received for histological analysis at our unit from January 2002 to December 2011 (10-year period), removed in the course of acute appendicectomy in children aged 3 to 15 years. Appendices were categorized by degree of inflammation and infestation with E . vermicularis.
RESULTS: Appendicectomy for clinical suspicion of acute appendicitis was performed in 2923 patients, 1694 (58%) male, median age 11.6 years. E . vermicularis was present in 4% of appendices; 25% of which showed concurrent acute inflammation. E . vermicularis infestation was more common in females (F : M 76% versus 24% of inflamed appendices and 66.7% versus 33.3% for non-inflamed appendices). European individuals showed higher representation in the E . vermicularis group than the total study population (79% versus 53% respectively).
CONCLUSION: E . vermicularis was found to be more common in females and those of European descent. Seventy-seven percent of patients with E . vermicularis did not have concurrent acute inflammation of the appendix on histological examination. The question remains as to whether infestation is protective of inflammation or whether infestation causes appendiceal colic and subsequent appendicectomy of a non-inflamed appendix, thereby protective of the morbidity of acute appendicitis.