Diagnosis of Enterobius Vermicularis Infestations

Enterobius vermicularis (pinworm or threadworm) is considered as the most common intestinal parasitic worm infestation of humans. About 200 million people are estimated to be infested with this nematode globally, children aged 5–10 years accounting for more than 30% of cases.1 The adult male and female enterobius worms inhabit the caecum of the human large intestine. The gravid females migrate to the perianal area mainly at night and lay up to 15 000 eggs (ova) which is strikingly shown in the video attached (Video S1, Supporting Information). A child's fingers get contaminated with these eggs and children acquire infection through ingestion of eggs when they put their fingers into the mouth. The eggs become mature quickly in the perianal region releasing larvae that can also migrate upwards through the anus resulting in further establishment of the infestation (autoinfection). In the absence of autoinfection, infestation usually lasts only 4–6 weeks. Some eggs may detach from the perianal region and contaminate clothing, bedding and other surfaces. Poor personal hygiene and overcrowding are considered as main risk factors for the infection. The infection is prevalent among children attending day-care facilities, pre-schools and primary schools. A majority of children with enterobiasis are asymptomatic. However, nocturnal perianal pruritus is characteristic, and may be associated with sleep disturbance, tooth grinding, bedwetting and irritability/restlessness. Rare serious complications such as appendicitis, eosinophilic enterocolitis and pelvic inflammatory disease occur due to migration of worms into adjacent anatomical sites. Figure 1 demonstrates cross sections of the worm in a biopsy taken in such instances. Stool examination detects only 5% of intestinal infestation in contrast to other common gastrointestinal helminth infections. The diagnostic test of choice is the ‘cellophane tape’ or ‘scotch tape’ test method. Direct application of clear cellophane or tape to the peri-anal region and then transfer onto to a standard glass slide can be submitted to microscopic examination to detect ova. To obtain better results specimens should be collected in early morning prior to washing the perianal area. The sensitivity of three consecutive tape collections is about 90%.2 The authors would like to thank Tony Henwood (The Children’s Hospital at Westmead, Westmead, New South Wales, Australia) for providing photograph. Video S1. As shown in this video, Enterobius vermicularis lays thousands of ova directly onto a child’s perineum such that stool is not the recommended specimen for laboratory confirmation of enterobiasis infestation. All paediatric trainees should understand the rationale for the ‘cellophane tape’ or ‘scotch tape’ test. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.