Enterobius vermicularis is the most common parasitic infection in developed countries of temperate and cool climates . A about 4%–28% of children worldwide are infected as showed by many reports, approximately 10 mm is the length of pinworms and live with their heads embedded in the ascending colon and adjacent bowel .
The feco-oral route is the most common route of human infection and the viability of eggs on clothing and bedding about two to three weeks, so that explained the easy spreading among family members . It is often considered not to be a serious disease due to its low pathogenicity .
Due to obstruction of appendiceal lumen, the presence of parasites in the appendix may cause appendiceal colic .
2. Case presentation
17 years old male pt. from Baghdad, Iraq. He was single,worker and lived with his family.
The pt. presented to our emergency department with history of pain in the R.t lower quadrant for 2 days before.
The pain start in the R.t lower quadrant as a mild colicky pain, at beginning the pain was interrupted then became continuous and increased in severity associated with fever, anorexia, nausea and later on with vomiting also. Pt. had no diarrhea. The pain decreased by analgesia (NSAID) and aggravated by movement.
Regarding patient review of systems nothing positive and past history was negative, he was not smoker and not alcoholic, patient had no previous drug history and no psychological illness.
A physical examination revealed right iliac fossa tenderness.
(McBurney's sign) A laboratory examination showed an elevated white blood cell (WBC) count at 13,600/μL with neutrophilia and a urine test showed five to six WBCs and no red blood cells. An abdominal ultrasound was done but not determined whether the appendix was inflamed or not; there were no positive findings related to other abdominal examination. An open appendectomy was performed. The macroscopic appearance of his appendix was inflamed and lumen filled with worms. The pathological examination revealed the lumen to contain E. vermicularis with lymphoid hyperplasia (Fig. 1, Fig. 2 and Fig. 3). Postoperatively, one oral dose of 100 mg of mebendazole was administered to our patient and his family members and was repeated after 14 days.
The only natural hosts of pinworms are humans .The gastrointestinal infection due to E. vermicularis occurs worldwide and is considered to be the most common helminth infection . Any socioeconomic levels can be infected but mostly children aged between 5 and 14 years . Deposits eggs in the perianal area by gravid female represent the beginning of the lifecycle and after ingestion eggs are hatched and larvae are produced in the small intestine then reaching the caecum and appendix where they are the usual sites of infestation .
Enterobius vermicularis infection leading to many pathologic changes which are ranging from lymphoid hyperplasia, acute and suppurative appendicitis to normal appendix but when lumen of appendix obstructed by worms that leading to rise the symptoms .
Infestation with E. vermicularis leading to appendiceal colic but sometimes the clinical presentation can be mimic symptoms of acute appendicitis which is occur because the infestation by these pin worms leading to lymphoid hyperplasia which may provoke the inflammatory process and then leading to clinical presentation of acute appendicitis, while acute appendicitis is reported only when neutrophilic infiltration is observed .
However, E. vermicularis occasionally may be associated with severe inflammation, ulceration and perforation, so our conclusion is that the presence of E.vermicularis in appendectomy specimens appears to be incidental rather than being a cause of appendicitis .
Infrequently the E. vermicularis can be found in appendectomy pathological specimens. Rarely, acute appendicitis caused by parasitic infections, especially in adults. So the clinical signs of intestinal parasite infection can be may mimic acute appendicitis. A careful evaluation of symptoms such as pruritus ani, or eosinophilia on laboratory examination, could prevent unnecessary appendectomies.
Written informed consent was obtained from the patient for publication of this case report and accompanying images.
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