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142 CHAPTER 6

MICROSCOPIC DIAGNOSTIC MICROSCOPIC DIAGNOSTIC

FEATURE FEATURE

General Classification—Ascarid General Classification—Ascarid
(Nematode egg) (Nematode worm)

Organism Ascaris lumbricoides Organism Ascaris lumbricoides
Specimen Required Feces adult “worm”
Stage Egg Specimen Required Feces
Size Fertilized egg: Stage Adult
45–75 μm Size 15–35 cm and 2–4 mm
Unfertilized egg: in diameter
80–90 μm Shape Round and elongated
Shape Broad and oval Motility Sluggish, curling
fertilized egg movements
Infertile eggs are Other Features Off-white to pale
longer, 80–90 μm yellow “worm” with
in length pointed tail
Shell Thick, yellow-brown, Sometimes described
and mammillated by patients as
Other Features Unfertilized eggs “earthworms”
show disorganized
internal contents
A. lumbricoides Ova WHIPWORM INFECTIONS
Adult worm Infertile egg
Whipworms are a type of roundworm of which there
are perhaps as many as 60 different species. Humans
are infected chiefly by a species of whipworm originally
called Trichuris trichuris, but currently identified as
T. trichiura, where they inhabit the large intestine of hu-
mans and animals. The name of the organism refers to
Fertile egg
the characteristic shape of the adult organism.
TRICHURIS TRICHIURA

The human whipworm (Trichuris trichiura or Trichoceph-
alus trichiuris) and previously known as Trichuris trichi-
ura, is one of the most prevalent parasitic roundworms
found worldwide. The existence of the organism has been
documented for many years and in the older literature it
Decorticated egg was described as causing a condition called trichuriasis
when it infects the large intestine of the human.
Delmar/Cengage Learning Morphology

The Trichuris trichiura parasite is commonly referred
to as the “whipworm” because of its resemblance in the
adult worm to a whip. The name refers to the shape of
the worm with the appearance of an old-fashioned buggy