Enterobius vermicularis (Pinworm)

A 7-year-old boy is brought to the pediatrician by his parents for evaluation of abdominal pain, which has been ongoing for the past 2 weeks. The pain is dull and intermittent. In addition, the parents have noticed that the patient frequently scratches his perianal region while asleep. Temperature is 37.5°C (99.5°F), blood pressure is 102/73 mmHg, and pulse is 87/min. Examination of the heart, lungs, and abdomen are unremarkable. Erythema is noted in the perianal region. A tape test is performed and reveals multiple ovoid eggs under microscopy. Which of the following pathogens is most likely responsible for this patient’s symptoms?