This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Which of the following nematode resides mainly in the caecum and appendix? 
Select and explain. 
A. Ascaris lumbricoides, B. Mansonella ozzardi, C. Enterobius vermicularis, D. All of these
C: Enterobius vermicularis
Answer: C: Enterobius vermicularis 
Explanation: Enterobius vermicularis is a nematode which lie attached to the mucosa of cecum. As its period of gravidity draws to a close it migrates down the colon and lay eggs in the perianal skin at night. Another nematode which resides predominantly in the cecum and colon is Trichuris trichura with its anterior poion threaded into the superficial mucosa. Infection occurs with the ingestion of eggs which that hatch in the duodenum releasing the larvae that mature before migrating to the large bowel.