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Questions and Answers
What is the appearance of Trichuris trichiura eggs?
What is the appearance of Trichuris trichiura eggs?
Which of the following therapies is used for treating infections caused by Trichuris trichiura?
Which of the following therapies is used for treating infections caused by Trichuris trichiura?
What type of diagnostic technique can be used to identify adult hookworms?
What type of diagnostic technique can be used to identify adult hookworms?
What typically characterizes mild infections of Trichuris trichiura?
What typically characterizes mild infections of Trichuris trichiura?
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Which life cycle stage of helmints is typically found in feces?
Which life cycle stage of helmints is typically found in feces?
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What is the primary habitat of N.a and A.d?
What is the primary habitat of N.a and A.d?
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Which symptom is NOT associated with the adult stage of N.a and A.d?
Which symptom is NOT associated with the adult stage of N.a and A.d?
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What type of eggs do N.a and A.d produce?
What type of eggs do N.a and A.d produce?
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Which of the following treatment options is specifically indicated for N.a and A.d infections?
Which of the following treatment options is specifically indicated for N.a and A.d infections?
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How much blood can A.d withdraw in a 24-hour period?
How much blood can A.d withdraw in a 24-hour period?
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What is a characteristic feature of nematodes?
What is a characteristic feature of nematodes?
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Which of the following is a soil-transmitted helminth?
Which of the following is a soil-transmitted helminth?
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Which symptom is associated with the larval stage of nematodes?
Which symptom is associated with the larval stage of nematodes?
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What is the typical habitat of adult Ascaris lumbricoides?
What is the typical habitat of adult Ascaris lumbricoides?
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What is a distinguishing feature of fertilized corticated eggs from Ascaris lumbricoides?
What is a distinguishing feature of fertilized corticated eggs from Ascaris lumbricoides?
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Which of the following is NOT a type of nematode based on habitat?
Which of the following is NOT a type of nematode based on habitat?
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What condition can result from the migration of adult nematodes?
What condition can result from the migration of adult nematodes?
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Which non-soil transmitted helminth infects muscle tissue?
Which non-soil transmitted helminth infects muscle tissue?
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Study Notes
Helminths
- Helminths are parasitic worms
- Lecture time for intestine nematodes (STH) is 50 minutes
- Lecture time for intestine nematodes (non STH) is 50 minutes
Classification of Helminths
- Helminths are divided into nematodes and platyhelminths
- Nematodes/Aschelminths include roundworms
- Platyhelminths include cestodes (tapeworms) and trematodes (flukes)
Nematodes
- Nematodes are cylindrical in shape
- They are covered by a cuticle
- They have a complete digestive system
- They have separate sexes
- Their life cycle includes ova, larval and adult stages
- They are classified into intestinal and blood/tissue nematodes
Intestinal Nematodes
- Soil-transmitted helminths include Ascaris lumbricoides, Trichuris trichiura, hookworms (Ancylostoma duodenale and Necator americanus), and Strongyloides stercoralis
- Non-soil transmitted helminths include Enterobius vermicularis and Trichinella spiralis
Nematodes in Animals
- Cutaneous larva migrans include Ancylostoma braziliense and Ancylostoma caninum
- Visceral larva migrans include Toxocara cati and Toxocara canis
Ascaris lumbricoides
- It is a soil-transmitted helminth
- The distribution is cosmopolitan, tropical, and subtropical areas
- The infection is caused by poor sanitation practices
- The infection is called Ascariasis
Ascaris lumbricoides Morphology
- Adult worms, females are 20-35 cm long, and males are less than 30 cm long
- The shape is similar to a pencil
- They have a creamy white or pinkish color
- The cuticle has fine circular striations
- The mouth has three oval lips
Ascaris lumbricoides Eggs
- Fertile eggs are 50-70 × 40-50 μm, and subspherical or round, yellowish-brown to dark brown
- The outer coating is thick with a mammilated protein coat
- Fertile decorticated eggs are thin-shelled, without protein coat
- Infertile eggs are 60-90 × 40-60 μm, elongated ellipsoidal, and have a more irregular outer appearance
- They are brown to dark brown, with a large number of granules inside
Ascaris lumbricoides Life Cycle
- The life cycle has 9 developmental stages
- The diagnostic stage of the egg is the 1-9 stages
Ascaris lumbricoides Pathology and Symptoms
- Larval infection may result in pneumonitis with eosinophilia (Loeffler syndrome)
- Adult worms may cause abdominal distention, diarrhea, vomiting, malnutrition, and symptoms like appendicitis or pancreatitis, and bowel obstruction
Ascaris lumbricoides Diagnosis
- Feces examination for eggs using direct smear, Lugol's solution, eosin, Kato-Katz technique or centrifugation
Ascaris lumbricoides Treatment
- Treatment includes Albendazole and Mebendazole
Trichuris trichiura
- It is a whipworm
- The adult worm is thread-like at the anterior end and bigger at the posterior
- Males are smaller than females and have a coiled tail
- Habitat : Cecum
- Adult worm invades intestinal mucosa
Trichuris trichiura Eggs
- The eggs are 50-54 × 22-23 μm, barrel-shaped, and brown to dark brown
- They have polar plugs at either end
- The shell has two layers
- Feces contain unsegmented stages of eggs
Trichuris trichiura Life Cycle
- Embryonated eggs are ingested, larvae hatch in the small intestine and migrate to the cecum
- The adult worm lives in the cecum
Trichuris trichiura Pathogenesis and Symptoms
- Mild infections may be asymptomatic
- Heavy infections may cause abdominal pain, distention, bloody or mucoid diarrhea
- Symptoms may be similar to appendicitis or prolapse recti
Trichuris trichiura Diagnosis
- Feces examination for eggs, same as ascariosis
Trichuris trichiura Treatment
- Treatment includes Mebendazole and Albendazole
Hookworm
- Includes Ancylostoma duodenale and Necator americanus
- Distribution: Tropical and subtropical areas
- Infections: Ancylostomiasis and Necatoriasis
- Morphology: Adult worms are "C" shaped for Ancylostoma duodenale and "S" shaped for Necator americanus; Females are about 1cm, Males are about 0.8 cm
- Mouth: Ancylostoma duodenale have teeth, Necator americanus have cutting plates
- Habitat: Small intestine; attach to mucosa, suck blood and mucosal substances, anti-coagulating secretion facilitates blood sucking
Hookworm Eggs
- Eggs are 55-75 μm × 35-40 μm, oval, thin-shelled, transparent
- They contain blastomeres (4-8 cells)
Hookworm Larvae
- Rhabditiform larvae (RL)
- Filariform larvae (FL) infective form
- N.a infective form = cutaneous
Hookworm Life Cycle
- Larvae penetrate skin (cutaneous)
- Develop to adult worms in small intestine
- Eggs passed in feces
Hookworm Pathology and Symptoms
- Larval: skin (ground itch), mild pulmonary symptoms
- Adult: Anemia (iron deficiency), gastrointestinal symptoms
Hookworm Diagnosis
- Eggs in stool
- Harada-Mori technique to differentiate species (FL)
Hookworm Treatment
- Albendazole, Mebendazole, Pirantel pamoate
Prevention
- Prevention of transmission to follow life cycle
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Description
Test your knowledge on the appearance, treatment, and characteristics of nematodes, specifically Trichuris trichiura and other related species. This quiz covers diagnostic techniques, life cycles, and symptoms associated with these parasitic infections.
