Page 164 - parasitology for medical and clinical laboratoryprofessionals

144 CHAPTER 6

not uncommon to find a T. trichiuris infection accompa-
nied by a second parasite such as A. lumbricoides. MICROSCOPIC DIAGNOSTIC
FEATURE
Laboratory Diagnosis
Stool specimens and identification of the eggs, which General Classification—Nematodal
are characteristic with their elongated shape and the whipworm egg
polar plugs found in the terminal ends, are evidence of Organism Trichuris trichiura
a T. trichiura infection. Identification and differentia- Specimen Required Feces
tion of eggs is the most common method for identifying Stage Egg most often
an infection by the whipworm. Routine concentration diagnostic with
methods may be necessary in order to recover both ova occasional adult
and adult parasites. Adult worms are rarely seen in fe- stages seen
cal samples but are useful in identifying an infection of Size Egg ranges from
T. trichiura; if seen, females are larger than males, as 50–55 3 22–23 μm
previously described, although this overlapping range Shape Eggs are smooth-
provides for little diagnostic value. The females have shelled and brown
a rounded posterior end compared to the male coun- with barrel
terparts which possess a coiled posterior end. Their shapes and are
characteristic eggs have a smooth shell and are barrel- unembryonated
shaped, brown, and have bipolar plugs. when passed;
characteristic
During the early stage of infection there may be only mucogelatinous
limited signs of infection in fecal samples. This is due to plugs on opposite
the cycles of periodic skin shedding and growth, which ends of elongated
must occur for a period of approximately 3 months be- eggs
fore adults mature and begin egg production. It should Shell Smooth shell surface;
be remembered that the mature Trichuris trichiura has a may be thick and
narrow anterior esophageal end and shorter and thicker yellow-brown with
posterior anus, a characteristic necessary to differentiate staining by bile
adult worms from other species of parasites. These pink- Other Features Pink to white larval
ish-white worms extend through the intestinal mucosa forms
T. trichiuria
and attach to the host through their slender anterior end
Adult worm
where they feed on tissue secretions. Mechanical dam-
age may occur in the intestinal mucosa when toxic or in-
flammatory damage to the intestines of the host occurs,
resulting in blood loss and anemia in victims with heavy
infections. Whipworm infections may also be accompa-
nied by concurrent infections with Giardia, Entamoeba
histolytica, Ascaris lumbricoides, and hookworms. This
fact requires that the parasitologist be especially careful
in ruling out other infections upon identification of one
particular species.
Ovum
Treatment and Prevention Delmar/Cengage Learning

A drug commonly used is that of mebendazole but pre-
vention is the best course as for most other parasites.
Good personal hygiene and the avoiding of contaminated