Karnatak PGET 2007 Microbiology MCQ Answer 5

The correct Answer is B

Enterobiasis is caused by infection with the pinworm, Enterobius vermicularis.

Transmission: Ingestion of eggs from the environment. A common autoinfection route in children is transfer of eggs from the perianal region to the mouth by contaminated fingers. Infection is also acquired from inhalation of eggs that adhere to mucus membranes and eventually are swallowed.

Location: The adult worms live in the proximal colon, cecum and appendix.

Morphology and life cycle: The adult females are about one centimeter in length. They have a sharply pointed posterior end which gives them the name, "pinworm". Male and female pinworms inhabit the cecum, ppendix and adjacent colon. The males die after copulation. The gravid females migrate down the colon, through the anus and lay their eggs on the perianal skin or they can explode releasing large numbers of eggs. The eggs become infectious within a few hours and may be directly ingested on contaminated fingers or spread to the environment by air currents. Retroinfection can occur. The entire cycle takes 4 – 6 weeks.

Diagnosis: Eggs are not usually found in the feces. Cellulose tape swabs (Scotch tape/ N.I.H. Swab) are applied to the anal folds and perianal skin in the morning before the patient bathes or goes to the bathroom. The tape is examined microscopically for the presence of pinworm eggs. Although seven consecutive negative swabs are necessary to exclude the diagnosis of enterobiasis, three or four swabs will detect the majority of infections. In some families there may be a strong psychological reaction to discovering the infection in their children (“pinworm psychosis”).

http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Enterobiasis_il.htm
http://www.biosci.ohio-state.edu/~parasite/enterobius.html

Category: Karnataka PGET 2007 MCQs