This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitology, Subject name: Microbiology
Most common presenting symptom of thread worm infection amongst the following is - 
Select and explain. 
A. Abdominal pain, B. Irritation and pruritus of perianal area, C. Uicaria, D. Vaginitis
B: Irritation and pruritus of perianal area
Answer: B: Irritation and pruritus of perianal area 
Explanation: Threadworm causes enterobiasis The worm produces intense irritation and pruritus of the perianal and perineal area when it crawls out of anus to lay eggs.This leads to scratching and excoriation of skin around anus. Ref:panikers textbook of Medical parasitology 8th edition page 196