Auto infection is seen with:

Ans. D. Enterobius vermicularisSource of infection of Enterobius: -a. Auto-infection: Scratching - fingers - patients' own mouth.b. Retro-infection: Eggs laid in perianal region - hatch - larvae - migrate back to anus.c. Pinworm infestation can be suspected from the history of perianal pruritus.d. Diagnosis depends on the demonstration of the eggs or adult worms.e. Eggs are present in the feces only in a small portion of patients & so feces examination is not useful in diagnosisf. They are deposited in large numbers on the perianal and perineal skin at night and can be demonstrated in swabs collected from sites early morning, before going to the toilet or bathing.g. Swabs from perianal folds are most often positive.h. The NIH swab (named after National Institute of Health, USA) has been widely used collection of specimens