Trichuris

• Trichuris trichiura


  • Soil-transmitted Helminth (STH) along with A. lumbricoides and hookworms
  • Disease of poverty
• Epidemiology


  • Worldwide distribution
  • Common in tropical regions (warm, most environment)
  • Present in temperate zone
  • 604 – 795 million infected worldwide
  • 5 – 15 years old: most commonly affected
• Adult Trichuris trichiura


  • Holomyarian somatic muscle arrangement
  • Flesh or pinkish slender nematode
  • Habitat: Colon, cecum
  • Male: 30 – 45 um
  • Female: 35 – 50 um
  • Anterior end: Attenuated anterior three-fifths traversed by a narrow esophagus resembling a string of beads, Secrete a pore-forming protein called TT47, Embed into the intestinal wall
  • Posterior end: Robust two-fifths containing intestine and single set of reproductive organs, Male: coiled with single spicule and retractile sheath, Female: blunt
  • Lays 3,000 – 10,000 eggs per day
• Trichuris trichiura Ova


  • Size: 50 – 54 um by 23 um
  • Lemon- or barrel- or football-shaped with plug-like translucent hyaline and refractile polar prominences
  • Unsegmented at oviposition, Embryonic development in the environment (2 – 3 weeks)
• Trichuris trichiura Larva


  • Layers of shell: Bile-stained layer (outermost, smooth, yellow-brown color), Albuminous layer (middle), Chorionic layer (innermost, transparent)
  • More susceptible to desiccation than A. lumbricoides
  • Soon after embryonated eggs are ingested, larvae escapes and penetrate the intestinal villi where they remain for 3 – 10 days

  
• Life Cycle of Trichuris trichiura

  1. 4 larval stages: 12 weeks

  2. NO heart-lung migration

  
• Pathogenesis and Clinical Manifestations


  • Intestinal Petechial Hemorrhages: Anterior portions embedded in the mucosa, Predispose to amoebic dysentery, Intestinal bleeding is common
  • Acute Appendicitis: Lumen of appendix filled with worms
  • Rectal prolapse in heavy chronic Trichuriasis: Blood-streaked diarrheal stools, Abdominal pain, Weight loss, Blood loss: 0.8 – 8.6 mL / day (lead to anemia), Infection causes muscle relaxation, resulting rectal prolapse
• Clinical Diagnosis


  Possible only in very heavy trichuriasis
• Laboratory Diagnosis


  Demonstration of unembryonated ova: Direct Fecal Smear with a drop of saline, Kato-Katz technique, Acid-Ether and Formalin-Ether (ethyl acetate) concentration techqniue, FLOTAC technique: more sensitive than Kato-Katz and ether/ethyl acetate concentration technique
• Treatment


  • Drug of choice: Mebendazole 100 mg BID x 3 days, Mebendazole 500 mg OD x 3 days
  • Alternative: Albendazole 400 mg OD x 3 days
• Prevention and Control


  1. WASHED framework for the control of STH: Provision of safe water, Environmental sanitation, Hygiene education, Regular deworming

  2. War on Worms (WOW)

  3. Mass Drug Administration among school-aged children: Biannual among STH prevalence >50%, Once a year among STH prevalence <50%, Drug: Mebendazole 500 mg one dose, Albendazole 40 mg one dose
• The unembryonated eggs are passed with the stool. In the soil, the eggs develop into a 2-cell stage, an advanced cleavage stage, and then they embryonate; eggs become infective in 15 to 30 days. After ingestion (soil-contaminated hands or food), the eggs hatch in the small intestine, and release larvae that mature and establish themselves as adults in the colon. The adult worms (approximately 4 cm in length) live in the cecum and ascending colon. The adult worms are fixed in that location, with the anterior portions threaded into the mucosa. The females begin to oviposit 60 to 70 days after infection. Female worms in the cecum shed between 3,000 and 20,000 eggs per day. The life span of the adults is about 1 year.