Answer to Case 479

Answer: Ascaris lumbricoides, adult female

The identification of this roundworm is based on its large size, tapered head and characteristic trilobate (3) "lips":

This worm can be further identified as a female based on its straight rather than coiled tail. Ali also astutely noted the presence of a "vulvar waist" - a narrowing at the junction on the anterior and middle thirds of the body, which also indicates that it is a female. Kamran was unable to express any eggs out of the worm; if found, the presence of eggs would also have confirmed the female gender. The size (30 cm) falls within the range of both male and female worms and therefore unfortunately cannot be used to identify the gender in this case.

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