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Background Helminthiasis remains a prevalent health issue among the pediatric population in both developed and developing countries. Recurrent enterobius vermicularis infection is a particularly distressing and sometimes embarrassing condition for children. While sporadic cases are common, repeated infections despite proper hygiene and regular deworming are uncommon and warrant further investigation. Methods This prospective observational study was conducted in Sylhet, Bangladesh between January 2022 and December 2024. All consecutive children presenting with treatment-refractory enterobiasis were enrolled. Comprehensive clinical evaluations and relevant investigations were performed to identify potential underlying or contributory factors. Treatment strategies were tailored accordingly, and clinical response was assessed based on symptom resolution. Results A total of 114 children were included, with a mean age of 88.25 ± 37.5 months and a male-to-female ratio of 1.65:1. All children presented with perianal itching and visible passage of worms (100%). Additional symptoms included abdominal pain (64%), anorexia (51%), vomiting (24%), nausea (16%), frequent small-volume defecation (9%), increased frequency of micturition (9%), nocturnal enuresis(7%), and encopresis (7%). Notably, constipation was present in 96% of cases—41% with occult and 55% with overt constipation ( p  < 0.0001), all of which had either been previously unrecognized or inadequately managed. Following the administration of appropriate laxative therapy along with antihelminthic therapy, significant symptomatic improvement was observed ( p  < 0.0001) with minimal failure rate (3%). Conclusion Constipation frequently coexists in patients with treatment-refractory enterobius vermicularis infections and proper management of constipation is essential for successful therapeutic outcomes.

Background Enterobiasis, caused by Enterobius vermicularis, is a common intestinal parasitic infection in children. Ectopic migration to extraintestinal sites, such as the greater omentum, is rare and often misdiagnosed due to nonspecific clinical manifestations and limited proficiency in identifying parasitic structures in paraffin-embedded histological sections. Case presentation A 12-year-old female presented with a three-day history of lower abdominal pain and a pelvic mass. Emergency laparoscopic resection revealed an ovarian serous cystadenoma and an omental mass. Initial histopathological examination of the omental mass suggested schistosome eggs; however, expert consultation confirmed a section of an adult female E. vermicularis containing eggs measuring up to 50 μm. The patient had no exposure to schistosomiasis-endemic areas but a history of prior pinworm infection, which had been treated with oral albendazole (400 mg once daily for 2 days). Subsequent adhesive tape tests over three consecutive days were negative, and perineal pruritus was resolved, confirming successful cure. The final diagnosis was ectopic enterobiasis of the greater omentum. Conclusions This case underscores the critical role of accurate morphological identification in distinguishing parasitic infections. Misdiagnosis, even in non-schistosomiasis-endemic areas, reflects insufficient training in parasitic morphology among healthcare professionals. Enhanced training on the morphology of common parasites and interpretation of paraffin-embedded histological sections is essential to improve diagnostic accuracy. Graphical Abstract

Enterobiasis, caused by the nematode Enterobius vermicularis, remains a widespread public health issue, yet data regarding its genetic structure in Southeast Europe are scarce. This study presents the first molecular and phylogenetic characterization of E. vermicularis isolates from Bulgaria. Between 2022 and 2025, perianal tape test samples were collected from 128 individuals (92.2% of whom were children) with enterobiasis from 17 regions of the country. Molecular identification was performed via nested PCR targeting a 324 bp fragment of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene, followed by Sanger sequencing. Phylogenetic relationships were analyzed using Maximum Likelihood (IQ-TREE), and population genetic indices were calculated using DnaSP v6. Phylogenetic analysis revealed that all 128 Bulgarian isolates belong to genotype B, clustering closely with sequences from other European and Asian countries. Genetic diversity analysis showed remarkably low variation, with a haplotype diversity (Hd) of 0.1507 ± 0.0416 and a nucleotide diversity (π) of 0.00082 ± 0.00015. Among the 11 identified haplotypes, a single dominant haplotype (Hap_1) accounted for 92.2% of all samples and was distributed across all sampled geographic regions. Tajima’s D was significantly negative (−2.314, < 0.05), suggesting a recent population expansion or purifying selection. The dominance of genotype B and the extremely low genetic diversity suggest a recent introduction or clonal expansion of E. vermicularis in Bulgaria. These findings provide essential baseline data for monitoring transmission dynamics and implementing effective control strategies in the Balkan region.

Background Intestinal parasitic infections are common in humans, especially among young children. These conditions are often asymptomatic and self-limiting, and diagnosis is mainly based on the search for ova and parasites in the stools since serology may be biased due to cross reactivity between parasites. Pinworm is common in children and is not usually associated with hypereosinophilia; adhesive-tape test is the gold standard testing for the microscopic detection of Enterobious vermicularis (Ev) eggs. Case presentation A 13-year-old boy was referred due to a self-resolving episode of vomiting and palpebral oedema after dinner, together with a history of chronic rhinitis, chronic cough, absolute IgA deficiency and Hashimoto’s thyroiditis and hypereosinophilia (higher value = 3140/µl). On evaluation we detected only palpable thyroid and hypertrophic nasal turbinates. Food allergy was excluded, but skin prick tests showed sensitization to house dust mites and cat epithelium and spirometry showed a marked obstructive pattern with positive bronchodilation test prompting the diagnosis of asthma for which maintenance inhaled treatment was started. Chest x-ray and abdomen ultrasound were negative. Further blood testing showed positive IgG anti-Echinococcus spp. and Strongyloides stercoralis and positive IgE for Ascaris, while Ev were detected both by the adhesive tape test and stool examination, so that we made a final diagnosis of pinworm infection. Three months after adequate treatment with pyrantel pamoate the adhesive-tape test turned out negative and blood testing showed a normal eosinophil count. The child later developed also type 1 diabetes. Conclusions We suggest the need to investigate for enterobiasis in children with hypereosinophilia and to consider autoimmunity as a potential confounding factor when interpreting serology for helminths.

Previous studies on the association of enterobiasis and chronic inflammatory diseases have revealed contradictory results. The interaction of Enterobius vermicularis infection in particular with gut microbiota and induced immune responses has never been thoroughly examined. In order to answer the question of whether exposure to pinworm and mebendazole can shift the intestinal microbial composition and immune responses, we recruited 109 (30 pinworm-negative, 79 pinworm-infected) first and fourth grade primary school children in Taichung, Taiwan, for a gut microbiome study and an intestinal cytokine and SIgA analysis. In the pinworm-infected individuals, fecal samples were collected again at 2 weeks after administration of 100 mg mebendazole. Gut microbiota diversity increased after Enterobius infection, and it peaked after administration of mebendazole. At the phylum level, pinworm infection and mebendazole deworming were associated with a decreased relative abundance of Fusobacteria and an increased proportion of Actinobacteria. At the genus level, the relative abundance of the probiotic Bifidobacterium increased after enterobiasis and mebendazole treatment. The intestinal SIgA level was found to be lower in the pinworm-infected group, and was elevated in half of the mebendazole-treated group. A higher proportion of pre-treatment Salmonella spp. was associated with a non-increase in SIgA after mebendazole deworming treatment. Childhood exposure to pinworm plus mebendazole is associated with increased bacterial diversity, an increased abundance of Actinobacteria including the probiotic Bifidobacterium, and a decreased proportion of Fusobacteria. The gut SIgA level was lower in the pinworm-infected group, and was increased in half of the individuals after mebendazole deworming treatment.

Background. Enterobius vermicularis is a nematode that predominantly affects the pediatric population, particularly in families with school-aged children. While it typically causes intestinal symptoms, rare cases of extraintestinal involvement have been reported, including female genital tract involvement and complications such as appendicitis or enterocolitis. Perianal parasitic abscesses are also rare, with only a few cases reported in the literature. Case Presentation. A 17-year-old female presented with abdominal pain during menstruation. Pelvic ultrasound revealed a septated cystic lesion located posterior to the uterus. Magnetic resonance imaging (MRI) demonstrated a perianal lesion with thick material, appearing iso- to hyperintense on both T1- and T2-weighted images. The lesion extended into the left gluteal muscles and showed peripheral contrast enhancement and diffusion restriction. Notably, there were no surrounding inflammatory changes, making an abscess diagnosis less likely. Surgical drainage revealed pus, and cytological analysis identified abundant parasitic oocytes consistent with E. vermicularis. The patient was treated with surgical drainage followed by pyrantel pamoate, resulting in near-complete resolution of the lesion at the one-month follow-up MRI. A literature review was also conducted to identify previously reported cases of parasitic abscesses and to explore the differential diagnoses of perianal cystic lesions. Conclusions. Perianal abscesses due to parasitic infections are rare, particularly those caused solely by E. vermicularis. Given the high prevalence in childhood infestations, parasitic abscesses should be considered in the differential diagnosis of perianal collections in pediatric patients, especially in the absence of peripheral inflammatory signs.

Pinworm (Enterobius vermicularis) remains the most prevalent helminth among preschool-aged children worldwide. Despite China's rapid development and decades of mass deworming, pinworm infection persists as a significant paediatric public-health problem. In this study, we aimed to understand the trends, clustering, and risk factors of pinworm infection in preschool settings of Jiangsu, China. A repeated cross-sectional study was conducted in 45 counties of Jiangsu Province from 2019 to 2024. Multi-stage cluster convenience sampling was applied. Each year, one rural preschool and one urban preschool were selected per county. The sample size for each school was 229 to obtain a 5% margin of error, an arbitrary design effect of 1.5 for a prevalence estimate of 10%, and a 10% nonresponse rate. A total of 27,925 children were investigated. Adhesive cellophane tape swabs were collected for confirmation of pinworm infection. A preschool-level permutation approach was used to evaluate clustering effects of pinworm infections within preschools, measured by infection rate ratio (IRR). Risk factors of pinworm infections were assessed by multiple logistic regression. Mediation analysis was conducted between the risk factor and pinworm infection. The overall pinworm infection rate was 0.48%, ranging form 1.22% in 2019 to 0.11% in 2024 and showing a downward trend (χ2 = 52.436, P < 0.001). Significant within-preschool clustering effect was observed in 2019 (IRR = 5.95, 95% lower CL = 3.77) and 2021 (IRR = 1.96, 95% lower CL = 1.35). Risk factors for preschool pinworm infection included migrant children (OR=3.911, 95%CI = 2.749-5.610) and older age (OR=1.443, 95%CI = 1.209-1.730). Mediation analysis indicated that parental education and family income collectively explain 55.2% of the association between migrant status and infection. Pinworm infections among preschool children demonstrate a within-preschool clustering effect. Despite the observed decline in infection rate of pinworms, targeted interventions are necessary in preschools, especially for migrant children. This study contributes to the broader understanding of enterobiasis and support the development of strategies to protect children's health in preschools.

In South Korea, Health Insurance Review and Assessment claims data contain comprehensive information on healthcare services for almost the entire population. The present study used claims data on parasitic diseases from 2011 to 2018, and associated medical expenses to investigate infection trends associated with endemic parasitic diseases in South Korea, including those not monitored by Korea Centers for Disease Control and Prevention. Basic data regarding each parasitic disease were curated from the Healthcare Bigdata Hub (http://opendata.hira.or.kr). Ten endemic parasitic diseases, three pandemic protozoan diseases, and three ectoparasitic diseases were evaluated between 2011 and 2018. Data on each parasitic disease included the number of patients of each sex, age range within 5 years, province, and total medical expenses. Heatmap and principal component analysis were performed to visualize the incidence pattern of parasitic diseases by provinces. Clonorchiasis and pinworm infections decreased remarkably from 6,097 and 4,018 infections in 2011 to 3,008 and 1,988 infections in 2018, respectively. Other endemic parasitic diseases mostly declined or remained steady over the 8-year period, except for anisakiasis, which doubled from 409 in 2011 to 818 in 2018. Provinces close to North Korea had a higher frequency of claims for Plasmodium vivax infection. The highest rate of clonorchiasis was in Gyeongsangnam-do, while that of anisakiasis was in southern Korea. Jeju province had the highest number of claims for cysticercosis, anisakiasis, pinworm infection, and soil-transmitted helminth infections. The total medical expense for anisakiasis was 65 million Korean won (57,000 US$) in 2011, rising to 237 million Korean won (206,000 US$) in 2018. The medical expense for trichomoniasis was 6,063 million won and for scabies was 1,669 million won in 2018. Since the claims data include only data reported by healthcare providers, some discrepancies might have occurred. Our findings provide the basis for a health policy to reduce further infections and medical expense.