Trichuriasis
Agent
Turchuriasis is caused by Trichuris trichiura, a parasitic nematode.
Taxonomy
Class: Adenophorea
Order:Stichosmida
Family: Trichocephaloidea
Synonyms
Whipworm
Morphology
| As their common name suggests, adult worms resemble whips. They have long, thin bodies with a tapered head and a thick posterior. This is opposite what was originally believed, that their heads were thicker than their tails. However, this morphology makes sense since the head of the worm contains only an esophagus, while the posterior end contains the intestines and reproductive organs. Adults are 3-5 cm in length with the females slightly larger than the males. Adult worms can live from 4-8 years in humans if the infection is left untreated. |
Picture of adult male and female worms, courtesy of Dr. Scott Smith |
|
picture of T. trichiura egg (CDC) |
Egg morphology is important to note because egg identification in the stool is the sole method of diagnosis. T. trichiura eggs have a characteristic football shape with two plugged ends that resist staining. Eggs are usually yellow brown when they are passed from the stool and color can be seen in contrast to the clear polar plugs. |
Life Cycle
Unembryonated eggs
are passed through the stool of an infected individual. Under favorable
conditions of high humidity, sandy soil, and warm temperatures eggs develop
into the infectious, embryonated, stage in 15-30 days. When infectious
eggs are ingested, they hatch in the small intestine and then migrate
to the cecum and ascending colon. Adult worms wind their thin heads into
the epithelium of the large intestine while the thick posterior end protrudes
into the lumen. Even though this is manner of establishing itself is reminiscent
of the hookworm, blood loss from T. trichiura is slight.
After about 60 days, female whipworms begin to produce eggs. Females are
quite impressive and can lay anywhere between 1,000 to 20,000 eggs per
day!