Overview Of The Parasite Trichuris Trichiuria

Clinical Manifestation

The parasite T trichiura lives primarily in the cecum and appendix but can also be found in large numbers in the colon and rectum. The differential diagnosis of chronic diarrhea requires consideration of several diseases, including celiac disease, inflammatory bowel disease, and irritable bowel syndrome. Patients infected with T. trichiura may present with a chronic dysentery-like syndrome if they have a massive infestation leading to anemia and growth retardation. In some cases, diarrhea may last for years without blood and mucus. However, once blood is evident, medical intervention may occur; in some cases the diagnosis requires colonoscopy. Also, in these cases, prolonged therapy may be necessary to eliminate the parasites. The dysentery seen in severe infections may mimic that seen in amebiasis. Most infections are light to moderate, with minimal or no symptoms. Hypochromic anemia may be seen in patients with prolonged, massive infection; however, the anemia is due to malnutrition and blood loss from the friable colon and is not related to blood ingestion by the parasite. Diagnosis and Identification Most whipworm infections can be easily diagnosed by finding the characteristic eggs in the stool. These eggs should be quantitated (rare, few, moderate, many), since light infections usually cause no problems and do not require therapy.

Note. T. trichiura eggs submitted in stool preserved with polyvinyl alcohol do not concentrate as well as those preserved in formalin. However, the very small numbers of eggs that might be missed in a concentrate obtained from polyvinyl alcohol-preserved stool material are not clinically significant. If the specimen was collected early in the infection, when egg production was minimal, eggs would be seen in later specimens (if they were submitted because of patient symptoms).

Eggs are normally recovered by using the routine ova and parasite examination from the direct wet mount or the concentration procedure. Egg recovery is generally not as good when concentrations are performed using polyvinyl alcohol-preserved fecal specimens; formalin or other non-polyvinyl alcohol preservatives are recommended.

Adult worms are very rarely seen. The eggs can usually be identified from the permanent stained smear, but morphology is more easily seen in the wet mount preparations (either direct wet mounts or from concentrated sediment).

Identification of Trichuris trichiura ova using trichrome stain: The thick-shelled Tnichiuris ova are the most easily identified of all the helminths. These ova will appear much as they would in a wet mount, stained dark red-brown, and retained their size and characteristics barrel shape. The diagnostic polar plugs and the embryo inside the shell are also easily seen.

The symptoms of trichuriasis are nonspecific, but the infection is readily diagnosed by identifying eggs in the feces. In heavy infections, the stools are frequently mucoid and contain Charcot-Leyden crystals. Concentration methods are required for diagnosis in light infections. In heavy infections, the parasite can be seen in the rectal mucosa by sigmoidoscopy.