E. vermicularis is an endemic disease seen in developing countries and especially in rural areas [10]. E. vermicularisis one of the most common helminthic infection in humans, and approximately half of the children aged between 5 and 10 years of age are affected, and 4% of these children have appendix infestation [11]. In this study, 62.5% of the patients were younger than 10 years old.
In a review study by Taghipour et al., the frequency of E. vermicularis in appendectomy specimens was found to be in the range of 2–8% [9]. In several studies involving pediatric patient groups, the rate of E. vermicularis was reported as 1.07%-7% [12–15]. In this study, we found a rate of 1.8% similar to the literature. In addition to the articles stating that E. vermicularisis encountered equally common in both genders, there are also studies stating that it is more common in girls [16, 17]. In this study, it was found 1.6 times more frequently in males, akin to the study of Yıldız et al. [14]. This is because the city where the study was conducted is in a rural area and boys are more involved in life.
The presence of parasites in the appendix lumen may cause various pathological conditions, including lymphoid hyperplasia mimicking an appendicitis [17, 18]. Previous studies have described the phenomenon of “appendix colic”, in which physical obstruction of the appendix lumen by E. vermicularis causes symptoms and signs like those seen in acute appendicitis [13].
In recent years, lymphoid follicles have been accepted as a part of functional appendix histology due to their important role in the intestinal immune system [19]. It was assumed that E. vermicularis instigated appendicitis by blocking the lumen, although only 23–71% of the pathology samples showed inflammation histologically [11]. In the study of Sousaj et al., they concluded that E. vermicularis causes neutrophils to accumulate in the submucosa and muscularis mucosa, possibly leading to pain symptoms and clinical suspicion of an appendicitis [12]. Also, they detected the presence of inflammation in the 64.8% of pathology samples, however in our series, the rate of inflammation, (acute and perforated appendicitis) detected in the pathology samples with E. vermicularis, was only 37.5%. Again, in our study, patients with reactive lymphoid hyperplasia had normal WBC, neutrophil count and CRP values, which are common inflammation markers. This suggests that inflammation in appendectomy specimens is due to secondary causes such as fecalith and bacteria rather than the presence of E. vermicularis invading the appendix lumen. The perforation rate of 12.5% that we found in our patients was similar to that of Alameyehu et al. [20].
If E. vermicularis is detected during appendectomy or in the examination of pathology specimens, anthelmintic treatment should promptly be initiated [7]. It is important to diagnose and treat this clinical entity, especially after perforated appendicitis, as there is an elevated risk of E. vermicularis contamination of the abdominal cavity [12]. In this study, E. vermicularis was not detected in the direct microscopy of the abscess fluid obtained from the percutaneous drainage fluid of our patient who developed intra-abdominal abscess three weeks after an appendicitis perforation. This leads us to believe that the abscess formation is rather a bacterial infection secondary to a perforation than an E. vermicularis infestation.
Common medical treatment modalities for E. vermicularis are mebendazole, albendazole (200 mg doses, single dose-one week apart) and pyrantel pamoate (10 mg/kg single doses-two weeks apart). These are safe and effective drugs with 90–100% cure rates [21]. As suggested in the literature we followed the same protocol and gave albendazole 200 mg single doses and repeat after one week to our patients and did not see any complications related to E. vermicularis in the postoperative period.
The study has a few limitations, such as being a retrospective review, small sample size, and sample evaluation of pathology specimens by different pathologists. Increasing the number of samples, working with a single pathologist, and long-term follow-up of patients may provide us with more detailed information in future studies.