37 Enterobius vermicularis infection: an uncommon cause of acute appendicitis in our environment

Abstract Introduction Gastrointestinal infections caused by parasites are usually infrequent in European countries, with Enterobius vermicularis being the most commonly isolated parasite. Its transmission occurs through the fecal-oral route and most commonly affects the paediatric population. This infection typically manifests as pruritus in the perianal area, although it can also lead to other complications, such as ileocolitis, mesenteric and pelvic abscesses or acute appendicitis. We present a clinical case of pelvic abscess and acute appendicitis caused by E. vermicularis. Case report A 17-year-old female patient of Cuban origin (last visit 5 years ago) attended the emergency department with a 2-day history of lower abdominal pain. She reported fever but no changes in bowel habits, nausea, or vomiting. She denied any previous similar episodes or high-risk sexual activity. She had a negative pregnancy test and laboratory tests showed leucocytosis with an elevated C-reactive protein (CRP). An ultrasound was performed, but due to inconclusive results, an abdominal CT scan was requested, revealing a tubo-ovarian abscess. The patient was admitted to the gynecology department for antibiotic therapy with ceftriaxone, doxycycline, and metronidazole. After 48 h, due to worsening of her clinical condition and laboratory results, a laparoscopic surgical review was decided. During surgery, purulent peritonitis was observed in the lower abdomen, along with a large pelvic abscess. The uterus and adnexa were examined without abnormalities; the ileocecal appendix was thickened with fibrin remnants, without signs of perforation. Abscess drainage was performed, the cavity was irrigated with abundant saline solution (SSF), and an appendectomy was carried out. Upon sectioning the appendiceal base between clips, mobile, filiform structures compatible with helminths were observed. The appendix was sent for histopathological and microbiological analysis. Postoperatively, broad spectrum antibiotic therapy was initiated with a single dose of albendazole (400 mg). An infectious diseases consultation was requested for follow-up. The patient had a favourable postoperative course and was discharged on the fifth postoperative day. In the histopathological results, the presence of Enterobius vermicularis and signs consistent with acute appendicitis were confirmed. Discussion Acute appendicitis is the most common surgical emergency. The presence of gastrointestinal parasites is unusual, and it’s more commonly related to sanitation status, culture, socioeconomic conditions, and climate. Symptoms of the parasitic intestinal infection can mimic those of appendicitis, with Enterobius vermicularis being the most frequently isolated, typically found in the terminal ileum, cecum, and ascending colon. Patients usually present with right lower quadrant pain, and imaging tests may show changes that confirm appendicular inflammation. However, several cases have been described where no histopathological findings consistent with acute inflammation were observed. Therefore, the presence of these parasites as a direct cause of acute appendicitis is still unclear. Their direct visualization or isolation is crucial, as surgery alone would not be sufficient as treatment. Antiparasitic therapy should be initiated, and an epidemiological study should be conducted. In conclusion, parasitic infections are infrequent but should be kept in mind, especially when evaluating the risks associated with specific patients.