<prompt> Most common presenting symptom of threadworm infection amongst the following is -Abdominal painRectal prolapseUrticariaVaginitis  <response>: Most patients infected of thread wormpin wormseat worm Enterobius vermicularis are asymptomatic.Most common complaint: Perianal and perineal pruritus pruritus ani- nocturnalearly morning.Other complaints: Abdominal pain, irritability and restlessness.All these symptoms caused by the female worms laying eggs on anal area.Severe infections: Sleep disturbances, neurosis, nail bite, grinding teeth at night.Adult worms can cause appendicitis. 