Q. What is Trichuris trichiura?
- Whipworm, a human intestinal nematode causing trichuriasis.
- Transmitted by ingestion of embryonated eggs from contaminated soil, vegetables or water.
Q. What are the causes and risk factors?
- Fecal‑oral contamination in areas with poor sanitation.
- Warm, moist soil favors egg development.
- Children playing in soil, eating uncooked leafy greens, using night‑soil as fertilizer.
Q. Types of infection based on worm burden
- Light infection: < 1000 eggs/g stool, often asymptomatic.
- Moderate infection: 1000–5000 eggs/g, mild abdominal discomfort, intermittent diarrhea.
- Heavy infection: > 5000 eggs/g, marked anemia, growth retardation, rectal prolapse.
Q. Morphology of the adult worm
- Length 3–5 cm, slender anterior “whip” (≈ 1/3) and thicker posterior “handle” (≈ 2/3).
- Anterior end embeds in colonic mucosa, posterior end free in lumen.
- Male: curved posterior end, spicules 0.5 mm.
- Female: larger, gravid uterus visible.
- Egg: barrel‑shaped, brown, 50–60 µm × 20–30 µm, bipolar plugs (characteristic).
Q. Life cycle (step‑wise, arrows show flow)
- Adult female releases unembryonated eggs →
- Eggs passed in feces onto soil →
- In soil, eggs embryonate (3–4 weeks, 25‑30 °C, moist) →
- Embryonated (infective) eggs ingested with contaminated food/water →
- Egg hatches in duodenum, larvae emerge →
- Larvae penetrate intestinal mucosa, migrate to caecum and ascending colon →
- Anterior end embeds in colonic crypts, matures into adult →
- Female starts laying eggs 60‑70 days after infection → cycle repeats.
Memory trick: “Dirty Soil Ingested Leads To Infection” (D = Dirty eggs in feces, S = Soil incubation, I = Ingested, L = Larvae hatch, T = To colon, I = Infection).
Q. Pathogenesis (step‑wise)
- Ingested egg → larva hatches → larva penetrates mucosa → anterior end lodges in crypts → mechanical irritation and local inflammation → micro‑bleeding → loss of blood and protein → anemia & hypoalbuminemia (heavy load) → chronic irritation → colitis, dysentery, rectal prolapse in children.
Q. Clinical manifestations
- Light infection: often asymptomatic.
- Moderate infection: intermittent abdominal pain, mild diarrhea, mucus in stool, occasional nausea.
- Heavy infection: chronic dysentery, visible blood in stool, iron‑deficiency anemia, growth retardation, weight loss, fatigue, night‑time abdominal cramps, rectal prolapse, perianal itching.
Q. Complications
- Severe anemia, protein‑energy malnutrition, growth delay in children.
- Rectal prolapse, colonic ulceration, secondary bacterial infection.
Q. Laboratory diagnosis
- Direct stool microscopy: identify barrel‑shaped eggs with bipolar plugs.
- Concentration techniques (formol‑ether, zinc sulfate flotation) to increase sensitivity.
- Egg count (eggs per gram) for grading infection intensity.
- Occasionally colonoscopy shows adult worms embedded in mucosa (rare).
Q. Management (pharmacological)
- Albendazole 400 mg single dose OR Mebendazole 100 mg single dose (repeat after 2 weeks if heavy).
- Pyrantel pamoate 11 mg/kg single dose (alternative).
- Ivermectin 200 µg/kg single dose (used where resistance suspected).
- Supportive: iron supplements, protein‑rich diet, vitamin A, deworming of family members.
Q. Prevention and control (public health)
- Improve sanitation, proper disposal of human feces.
- Health education on washing vegetables, hand‑washing after defecation.
- Periodic mass deworming in endemic areas (WHO recommendation: school‑age children every 6‑12 months).
- Use of latrines, avoid night‑soil as fertilizer.
Q. Key exam points to remember (MUHS + NCH)
- Whip‑shaped adult with anterior end embedded in colon.
- Barrel‑shaped egg with bipolar plugs is diagnostic.
- Life cycle completed entirely in human and soil (no intermediate host).
- Heavy infection → anemia, growth retardation, rectal prolapse.
- Single‑dose albendazole/ mebendazole is drug of choice.