enterobius vermicularis: endoscopic opportunistic ...

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ENTEROBIUS VERMICULARIS: ENDOSCOPIC OPPORTUNISTIC DIAGNOSIS IN A POORLY SYMPTOMATIC INFECTION. ENTEROBIUS VERMICULARIS: UNA DIAGNOSI ENDOSCOPICA OCCASIONALE IN UNA OSSIURIASI PAUCISINTOMATICA.

Pontone S1, Leonetti G1, Brighi M1, Pontone P1

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Department of Surgical Sciences, “Sapienza” University of Rome, Italy Dipartimento di Scienze Chirurgiche, “Sapienza” Università di Roma

Citation: Pontone S, Leonetti G, Brighi M, Pontone P. Enterobius vermicularis: endoscopic opportunistic diagnosis in a poorly symptomatic infection. Prevent Res 2013; 3 (1):45-49. Available from: http://www.preventionandresearch.com/ .

Key words: Enterobius vermicularis, Oxyuriasis, Parasitic infection, Colonoscopy Parole chiave: Enterobius vermicularis, Ossiuriasi, Infezioni parassitarie, Colonscopia

Abstract Enterobius vermicularis gastrointestinal infestation is considered as the most common helminthes infection worldwide and is promoted by inadequate personal and community hygiene. The parasite have a hand-to-mouth transmission resulting from scratching of perianal region, where the female parasite lays its eggs. Usually there are few symptoms as the infection is well tolerate. More frequently in children this infestation may be responsible for several non-specific (loss of appetite, abdominal pain, irritability, and pallor) and peculiar symptoms (anal itching, sleep disorders, restlessness and irritability). Scratching often cause skin irritation that, in more severe cases, arise through eczematous dermatitis, haemorrhage or secondary bacterial infections. Sometimes the infection can reach the female genital tract causing pelvic manifestations. When oxyuriasis is suspected, the confirmation is obtained by cello-tape test and the mebendazole based

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Jan-Mar 2013|P&R Scientific|Volume 3|N°1

Enterobius vermicularis: endoscopic opportunistic diagnosis in a poorly symptomatic infection

treatment is usually effective. Coproscopic tests may establish the diagnosis also in unclear cases without typical symptoms. Treatment includes an antihelminthic agent for the patient and household members as well as home hygiene measures. The diagnosis in adult patients is infrequent as the appearance of specimens during colonoscopy and endoscopists may not suspect its presence. However, the association of Enterobius vermicularis infestation with acute appendicitis varies from 0.2–41.8%. Thus, the early differential diagnosis, in these cases can exclude surgery and postoperative complications caused by the abdominal cavity parasitic contamination. We report about an endoscopic diagnosis of oxyuriasis in a poorly symptomatic patient undergone colonoscopy as polypectomy follow-up.

Abstract L’infezione intestinale da Enterobius vermicularis è considerata essere una delle più diffuse elmintiasi ed è frequentemente associata ad una inadeguata igiene personale e di comunità. Questo parassita si trasmette per via orofecale infestando la regione perianale ove gli esemplari femminili adulti depositano le uova. Tipicamente l’infezione viene ben tollerata vista la scarsità dei sintomi provocati. Più frequentemente nei bambini il parassita può essere responsabile di sintomi aspecifici (anoressia, dolore addominale, irritabilità e pallore) e specifici (prurito anale, disturbi del sonno). Le lesioni da grattamento, provocando una irritazione cutanea costante, nei casi più severi portano alla comparsa di dermatite eczematosa, emorragia e superinfezione batterica. Talvolta l’infestazione può raggiungere il tratto genitourinario femminile causando manifestazioni pelviche. Qualora l’enterobiasi venga sospettata, lo Scotch Test rappresenta un metodo mininvasivo per la conferma diagnostica, anche nei casi senza manifestazioni tipiche, ed il trattamento mediante Mebendazolo una cura efficace. La diagnosi endoscopica, così come il sospetto diagnostico nell’adulto non è frequente, così l’endoscopista potrebbe sotto pesare la possibile infestazione. Tuttavia, l’associazione tra enterobiasi ed appendicite è dimostrabile nello 0.2-41.8% dei casi. Così, la diagnosi differenziale, in questi casi, se precocemente effettuata, può escludere il trattamento chirurgico e conseguentemente le possibili complicanze postoperatorie ad esso collegate. Nel nostro caso, viene descritto un caso di diagnosi esclusivamente endoscopica di ossiuriasi colica in un paziente paucisintomatico, sottoposto a colonscopia totale per controllo in una pregressa polipectomia.

Background Enterobius vermicularis (Ev) gastrointestinal infestation is considered as the most common helminthes infection (1) with a high prevalence in developing countries (2). The fecal-oral route is the most common infection route for human. Poor sanitation is closely linked to the dissemination of this parasite and young children are particularly at risk. More frequently in children, the Ev infection may be responsible for loss of appetite, abdominal pain, irritability, and pallor, but the most common symptom is sleep disturbance caused by pruritus ani (anal itching), reported in 33 percent of patients (3). Thus, the parasite have a hand-to-mouth transmission resulting from scratching of perianal region, where the female parasite lays its eggs (4). Usually there are few symptoms as the infection is well tolerate. However, rare complications, primarily caused by the worms migrating into the genital and urinary tract, have been reported (5, 6, 7, 8, 9). When oxyuriasis is suspected, the confirmation is obtained by cello-tape test. This is an effective and minimally invasive method that is performed in the morning pressing the tape onto the perianal area before bathing or defecation. The microscope slide examination may reveal the eggs which are rarely found in the stool. The examination should be repeated for three consecutive days to be effective. While in children the diagnosis is easy, sometimes in adults, considering the embarrassment that may occur for this topic, the diagnosis is delayed (10). Furthermore, bowel preparation (BP) prior to a colonoscopy examination frequently lowers the chances of detecting the worms macroscopically (11). Thus, endoscopic diagnosis is infrequent as the endoscopist may not suspect its presence. In our case, we describe a oxyuriasis in an apparently asymptomatic adult patient.


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Case Report An Italian 51-year-old man presented to our endoscopic unit for a colonoscopy as follow-up to a previous right colon polypectomy for a tubulo-villous adenoma with a low-grade dysplasia, three years before. He denied any alarm symptoms, or change in bowel habits. The examination was performed under conscious sedation by midazolam (0,07 mg/kg). The cecum was easily reached, although the 4L-PEG based BP of the right colon was suboptimal because of the presence of copious liquid faecal residues. We try to aspirate the residues in the right colon in order to obtain an optimal mucosal visualization. Thus, during the cecum exploration a single Ev specimen was seen protruding from fecal residues firstly (Fig. 1) and then clearly detected (Fig. 2). When questioned for possible symptoms, he reported only the presence of mild anal itching. Moreover, until then the presence of II grade hemorrhoids justified the symptom. A single oral dose of 100 mg mebendazole, which was repeated 10 days later, were prescribed and a cello-tape test was performed for all household members. A subsequent diagnosis of oxyuriasis was performed in two household members (wife and 9years-old daughter).

Fig. 1 - A white pinworm hiding among the fecal residue (black circle).


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Fig. 2 - Adult Ev female pinworm (8-13mm) with developed reproductive organs (white area) in ascending colon. The males, expelled immediately after copulation, are frequently not visible because they have smaller size of females (2-5 mm).

Discussion Oxyuriasis is mainly seen in children between five and fourteen years and is frequently treated by medication. However, this disease may also be of surgical interest because of some atypical manifestations. One of these unusual manifestations is represented by acute or chronic appendicitis. Appendectomy is one of the most frequently performed operations worldwide and the association of Enterobius vermicularis infestation with acute appendicitis varies from 0.2– 41.8% (12), whereas not all appendicitis are surgically treated. In a review concerning unusual histologic findings during appendectomy, Akbulut et al (13), described a 0.5% of appendicitis caused by Ev in 80,698 appendectomies. The parasite can creep into the appendix and cause the obstruction, a tissue reaction or actively penetrate the intestinal wall. However, despite the presence of Ev is associated with chronic inflammatory infiltrates and eosinophilia (14, 15), we cannot determine if inflammation is already present before infection. However, the early differential diagnosis, in these cases can exclude surgery and post-operative complications caused by the abdominal cavity parasitic contamination. Although enterobiasis is mainly seen in tropical countries with lower socioeconomic levels, endoscopists practicing in industrialized countries, must be aware of this condition in their differential diagnosis (10, 14). Furthermore, the symptoms linked to the pinworms infestation is common to many benign pathologies of the anal region, which may justify an endoscopic examination. Thus, the possibility of being faced with a case of undiagnosed oxyuriasis, also if usually unexpected (16), is higher in the case of a digestive endoscopy, especially if the patient is in direct contact with school-age children. In our case, the endoscopic diagnosis has allowed an immediate patient treatment and the subsequent diagnosis of oxyuriasis in two household members (wife and daughter). Moreover, from the family history, there is a high probability that the initial infection was in the 9-year old daughter.

Patients with intestinal parasitic

infestation would have undergone a previous medical examination for non-specific abdominal symptoms. The association of anal itching, previous abdominal pain episodes, eosinophilia and proximity to a school-age child, should suggest the presence of a parasitic infection. In this case, a cello-tape test can prevent the unjustified endoscopy or surgery.


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Conclusions Usually, the endoscopy cannot be considered an appropriate test for the oxyuriasis diagnosis for its lack of sensitivity. However, considering the similarity of the symptoms manifested with other anorectal benign pathologies, the endoscopists should always give proper weight to the factors that may predict a possible parasitic infestation.

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10. Pontone S, Magliocca FM, Cancrini G. An embarrassed patient was unmasked by the endoscopic diagnosis. A case of Enterobius vermicularis infection in Italy. Am J Gastroenterol 2012;107(8):contents. 11. Hirai Y, Ainoda Y, Nakamura-Uchiyama F, et al. Unusual colonoscopic view of Enterobius vermicularis. Intern Med 2011;50(6):657. 12. Arca MJ, Gates RL, Groner JI, et al. Clinical manifestations of appendicial pinworms in children:an institutional experience and a review of the literature. Pediatr Surg Int 2004,20:372-375. 13. Dahlstrom JE, Macarthur EB. Enterobius vermicularis: a possible cause of symptoms resembling appendicitis. Aust N Z J Surg 1994, 64:692-694. 14. Akbulut S, Tas M, Sogutcu N, et al. Unusual histopathological findings in appendectomy specimens: a retrospective analysis and literature review. World J Gastroenterol 2011;17(15):1961-1970. 15. Surmont I, Liu LX. Enteritis, eosinophilia and enterovius vermicularis. Lancet 1995, 346:1167. 16. Petro M, Iavu K, Minocha A. Unusual endoscopic and microscopic view of Enterobius vermicularis: a case report with a review of the literature. South Med J 2005;98(9):927-929.

Corresponding Author: Stefano Pontone Department of Surgical Sciences, “Sapienza” University of Rome, Italy e-mail: [email protected]

Autore di riferimento: Stefano Pontone Dipartimento di Scienze Chirurgiche, “Sapienza” Università di Roma e-mail: [email protected]


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