Nematoda Roundworms Overview
27 Questions
2 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the role of copepods in the lifecycle of the Guinea worm?

  • They are used as a food source for humans.
  • They undergo two molts and develop into L3 larvae. (correct)
  • They are the final host for the adult worm.
  • They help in the transmission of L1 larvae.

    • The Guinea worm can be effectively treated with available drugs.

    False (B)

    What is one specific measure to control Guinea worm transmission related to drinking water?

    Promote the use of water filtration tools or provide safe and clean drinking water.

    The female Guinea worm emerges from the skin after __________ of infection.

    <p>one year</p> Signup and view all the answers

    Match the control measures with their appropriate categories:

    <p>Monitoring system for new cases = Surveillance Safe water sources inspection = Drinking Water Education campaigns = Community Involvement Provide protective footwear = Host Infection Control</p> Signup and view all the answers

    What type of body cavity do nematodes have?

    <p>Pseudocoel (B)</p> Signup and view all the answers

    Nematodes have a circulatory system.

    <p>False (B)</p> Signup and view all the answers

    What is the primary mode of reproduction in nematodes?

    <p>Sexual reproduction</p> Signup and view all the answers

    Trichinella spiralis is classified under the class ________.

    <p>Adenophorea</p> Signup and view all the answers

    Which of the following structures are likely chemosensory in nematodes?

    <p>Amphids and phasmids (D)</p> Signup and view all the answers

    Match the following nematode structures with their functions:

    <p>Cuticle = Protection and structure Spicules = Reproductive function in males Amphids = Chemosensory reception Nurse cells = Support and nourish larvae</p> Signup and view all the answers

    What is the significance of the cysts formed by the larvae of Trichinella spiralis in host muscle tissue?

    <p>Cysts nourish and protect the larvae.</p> Signup and view all the answers

    Nematodes can change their body diameter.

    <p>False (B)</p> Signup and view all the answers

    What is one of the primary effects of trichinellosis on skeletal muscle?

    <p>Intense muscle pain and inflammation (D)</p> Signup and view all the answers

    The adult Strongyloides stercoralis can reproduce through parthenogenesis.

    <p>True (A)</p> Signup and view all the answers

    Which condition is caused by the adult Onchocerca volvulus in the host?

    <p>Onchocercomas</p> Signup and view all the answers

    The secretion of ___________ from infected muscles helps mask them from the immune system.

    <p>tyvelosylated peptides</p> Signup and view all the answers

    Match the following parasites with their associated diseases:

    <p>Dracunculus medinensis = Dracunculiasis Onchocerca volvulus = Onchocerciasis Strongyloides stercoralis = Strongyloidiasis Trichinella spiralis = Trichinellosis</p> Signup and view all the answers

    What is one significant symptom of hyperinfection in Strongyloides stercoralis?

    <p>Intestinal bleeding (D)</p> Signup and view all the answers

    Ivermectin is effective against many tapeworms and flukes.

    <p>False (B)</p> Signup and view all the answers

    What type of larvae do humans ingest when consuming unfiltered water that leads to dracunculiasis?

    <p>L3 larvae</p> Signup and view all the answers

    Onchocerca volvulus is transmitted through the bite of a ___________.

    <p>black fly</p> Signup and view all the answers

    Which of the following is a known treatment for trichinellosis?

    <p>Albendazole (A)</p> Signup and view all the answers

    Elevated muscle enzymes in the blood indicate possible muscle damage.

    <p>True (A)</p> Signup and view all the answers

    What is a common outcome of the inflammation caused by adult Onchocerca volvulus worms?

    <p>Elephantiasis</p> Signup and view all the answers

    Larvae of Strongyloides stercoralis can migrate to the ___________ causing asthma-like symptoms.

    <p>lungs</p> Signup and view all the answers

    Which protein released from dying Onchocerca volvulus larvae contributes to inflammation?

    <p>Wolbachia Surface Protein (C)</p> Signup and view all the answers

    Flashcards

    Guinea worm life cycle

    A parasitic worm where the female worm emerges from a blister on the skin, releasing larvae into water. Copepods consume the larvae. After molting in the copepod, the larvae become infective and are consumed by humans when drinking contaminated water.

    Guinea worm eradication strategy

    A multi-pronged approach including surveillance to track cases, interventions focusing on safe water, treatment of infected people, community engagement and education to control the disease's transmission.

    Surveillance in guinea worm control

    A system for monitoring and reporting new cases, mapping affected areas, and using technology for efficient tracking of the disease.

    Safe water access in guinea worm control

    Interventions like providing safe drinking water, using water filtration tools, and regularly inspecting water sources to remove infective larvae and copepods from the water supply.

    Signup and view all the flashcards

    Community involvement in guinea worm control

    Engaging local leaders and community organizations to spread awareness about the disease, promote safe water practices, advocate for complete eradication, and empower communities to fight the disease together.

    Signup and view all the flashcards

    Trichinella spiralis life cycle

    A parasitic nematode that causes trichinellosis, humans eat undercooked pork/wild game leading to encapsulated larvae developing inside muscle cells

    Signup and view all the flashcards

    Nematode characteristics

    Bilaterally symmetrical worms with a pseudocoel and a tough cuticle, lack circular muscles & circulatory/respiratory system. Have a complete digestive system and excretory system and reproduce sexually.

    Signup and view all the flashcards

    Nematode's excretory system

    Consists of glands and canals, with an excretory pore, managing waste.

    Signup and view all the flashcards

    Trichinella spiralis infection

    Causes trichinellosis, a nematode with an intracellular parasitic stage, residing within skeletal muscle tissues. Infection comes from eating undercooked pork or wild game.

    Signup and view all the flashcards

    Nematode reproduction

    Hermaphroditic; internal fertilization through sexual reproduction. They are also able to reproduce oviviparously.

    Signup and view all the flashcards

    Nematode body plan

    Bilaterally symmetrical worm-shape; a pseudocoelom, with a tough cuticle secreted by the underlying hypodermis to protect the worm.

    Signup and view all the flashcards

    Trichinella life cycle: muscle damage

    Larvae cause muscle trauma, initially by damaging the sarcolemma and then inhibiting protein/enzyme production, triggering some myofibril damage.

    Signup and view all the flashcards

    Nematode feeding habits

    Generally free-living; they live anywhere and eat nearly anything, with some species being endoparasites.

    Signup and view all the flashcards

    Trichinella spiralis: Muscle Damage

    The larvae of Trichinella spiralis cause damage to muscle tissue by disrupting the sarcolemma, inhibiting protein and enzyme production, and causing myofibril damage.

    Signup and view all the flashcards

    Trichinella spiralis: Transmission

    Humans become infected with Trichinella spiralis by consuming undercooked pork or wild game that contains encysted larvae.

    Signup and view all the flashcards

    Trichinella spiralis: Symptoms

    The symptoms of trichinellosis include nausea, fever, diarrhea, muscle pain, inflammation, and impaired muscle contraction.

    Signup and view all the flashcards

    Trichinella spiralis: Treatment

    Trichinellosis is treated with albendazole or mebendazole, drugs that target parasitic worms.

    Signup and view all the flashcards

    Strongyloides stercoralis: Life Cycle

    Strongyloides stercoralis has two life cycles: a free-living stage that involves males and females, and a parasitic stage with only females that reproduce through parthenogenesis.

    Signup and view all the flashcards

    Strongyloides stercoralis: Transmission

    Transmission of Strongyloides stercoralis occurs through skin penetration (bare feet) or ingestion of infective larvae.

    Signup and view all the flashcards

    Strongyloides stercoralis: Autoinfection

    The infective larval stage of Strongyloides stercoralis can re-infect the same host through the intestinal mucosa or perianal skin, leading to hyperinfection in immunocompromised individuals.

    Signup and view all the flashcards

    Strongyloides stercoralis: Hyperinfection

    Excessive autoinfection of Strongyloides stercoralis in immunocompromised individuals can cause a hyperinfection, spreading to internal organs and potentially leading to fatality.

    Signup and view all the flashcards

    Onchocerca volvulus: Life Cycle

    The black fly is the intermediate host of Onchocerca volvulus, transmitting the infective larvae to humans through a blood meal.

    Signup and view all the flashcards

    Onchocerca volvulus: Nodules

    Adult Onchocerca volvulus worms live in subcutaneous tissues, forming nodules called onchocercomas, which can block lymphatic fluid flow.

    Signup and view all the flashcards

    Onchocerca volvulus: Wolbachia

    Onchocerca volvulus worms harbor a symbiotic bacterium called Wolbachia pipientis, which contributes to the severe immunopathological response during infection.

    Signup and view all the flashcards

    Onchocerca volvulus: Pathology

    Onchocerca volvulus infection can cause various pathologies, including onchocercomas, elephantiasis, severe onchodermatitis, and river blindness.

    Signup and view all the flashcards

    Ivermectin: Mechanism of Action

    Ivermectin acts on glutamate-gated chloride channels (GluCls) found exclusively in protostomes, inhibiting the motility, feeding, and reproduction of nematode parasites.

    Signup and view all the flashcards

    Dracunculus medinensis: Life Cycle

    Dracunculus medinensis is transmitted via contaminated water containing copepods infected with infective larvae.

    Signup and view all the flashcards

    Dracunculus medinensis: Transmission

    Humans contract dracunculiasis by drinking unfiltered water containing copepods infected with Dracunculus medinensis larvae.

    Signup and view all the flashcards

    Study Notes

    Nematoda (Roundworms)

    • Covered in a tough, non-living cuticle secreted by the hypodermis.
    • Undergo four molts to reach adulthood.
    • Possess a pseudocoelom (body cavity). Body fluid pressure is high, enabling lashing movements.
    • Amphids (anterior) and phasmids (posterior) are chemosensory structures.
    • Some male nematodes have spicules and a copulatory bursa for mating.
    • Two main classes: Adenophorea and Secernentea.
    • Bilaterally symmetrical and worm-shaped (veriform).
    • Anterior end of some adults has hooks, teeth, or plates in the buccal cavity.
    • Complete digestive system with a subterminal anus.
    • Lack circular muscles; movement is by lashing. Cannot change diameter.
    • Lack circulatory and respiratory systems.
    • Excretory system with glands and canals open to an excretory pore.
    • Hermaphroditic, with internal fertilization and sexual reproduction.
    • Feed on a wide variety of materials and live in diverse habitats; most are free-living, but some are endoparasites.

    Trichinella spiralis

    • Class Adenophorea.
    • Causes trichinellosis, a significant intracellular parasite.
    • Humans are both definitive and intermediate hosts.
    • Infection results from ingesting undercooked pork or wild game containing encapsulated larvae.
    • Globally prevalent with a varied host range.

    Trichinella spiralis Life Cycle

    • Ingestion of encapsulated L1 larvae.
    • Larvae hatch and penetrate intestinal mucosa.
    • Larvae undergo four molts to mature into adult worms.
    • Mating occurs; females burrow deeper into the intestinal wall, laying eggs.
    • Newborn larvae are distributed via the circulatory system to skeletal muscles.
    • Larvae penetrate muscle tissue, causing dramatic tissue changes.
    • Nurse cells nourish and protect developing larvae.
    • The larva-nurse cell complex is enclosed in a collagen capsule, forming a cyst (20-28 days post-infection).
    • Significant changes occur within the muscle fiber, including damage to the sarcolemma and protein/enzyme destruction.
    • Satellite cells (muscle repair cells) are affected, becoming nurse cells instead of repairing tissue.
    • Upregulation of collagen type IV and VI occurs, and angiogenesis (blood vessel formation) is stimulated by VEGF.
    • Larvae enter hypobiosis (developmental arrest) within the collagen capsule.
    • When infected muscle is consumed by another carnivore, the larvae are released for re-infection.

    Trichinellosis Pathology

    • Initial infection involves adult worm penetration into intestinal mucosa (nausea, fever, diarrhea).
    • Larval migration can cause pneumonia, edema, conjunctivitis, meningitis, myocarditis, and peritonitis.
    • Muscle pain, inflammation, impaired contraction, respiratory difficulty, and potential heart/nerve damage are common complications.
    • Treatment involves albendazole or mebendazole.
    • Elevated muscle enzymes (CPK) are often detected in the blood.

    Soil-Transmitted Helminths (STH)

    • Strongyloides stercoralis: Parasite found in humans, primates, cats, and dogs.
    • Alternates between a free-living and parasitic life cycle. Both stages involve four larval stages and an egg-laying adult.
      • Free-living stage has both sexes, while parasitic stage is all-female (parthenogenesis).
    • Phenotypic plasticity, where free-living larvae in unfavorable conditions develop into infective L2 filariform larva.
    • Transmission typically via skin penetration or ingestion.

    Strongyloides stercoralis Life Cycle and Pathology

    • Skin penetration leads to acute inflammation.
    • Larval migration to the lungs causes asthma-like symptoms.
    • Adult worms in the small intestine lead to symptoms such as pain, nausea, diarrhea, and intestinal bleeding.
    • Autoinfection (L3 larvae re-infecting host) is possible, potentially leading to hyperinfection in immunocompromised individuals.
    • Hyperinfection can severely affect various organs (liver, lungs, kidneys, etc.).

    Onchocerca volvulus (River Blindness)

    • Causes onchocerciasis.
    • Introduction to South America via slave trade.
    • Adult females are larger than males.

    Onchocerca volvulus Life Cycle

    • Infected black flies transmit the disease.
    • L3 larvae develop into adults in subcutaneous tissues.
    • Adults produce microfilariae that are found in the skin and can migrate to organs, like the eye.
    • Black flies ingest microfilariae (L3 larvae development).
    • Adults live in subcutaneous tissues forming nodules. (Onchocercomas)
    • Microfilariae development in black flies, followed by re-infection of humans.

    Onchocerca volvulus Pathology

    • Nodules (onchocercomas) form due to host immune response.
    • Infections can cause elephantiasis (swelling due to lymphatic blockage).
    • Microfilaria mortality elicits an immunopathological response, including severe onchodermatitis and potential eye damage.
    • Wolbachia pipientis: A symbiotic bacterium associated with Onchocerca. It's acquired via horizontal gene transfer.
    • Wolbachia surface protein (WSP) triggers inflammation and damage to host tissues, contributing to river blindness (ocular damage).

    Ivermectin

    • Effective against many nematodes and ectoparasites.
    • Acts on glutamate-gated chloride channels found only in protostomes.
    • Inhibits nematode motility, feeding, and reproduction at nanomolar concentrations.

    Dracunculus medinensis (Guinea Worm)

    • Causes dracunculiasis, prevalent in arid regions.
    • Transmission predominantly via consumption of infected copepods in unfiltered water.

    Dracunculus medinensis Life Cycle

    • Drinking contaminated water containing copepods containing L3 larvae.
    • Larvae penetrate the intestinal wall, develop into adults, and mature in connective tissues.
    • Mature female worms migrate to host skin, causing a blister and releasing L1 larvae.
    • Released L1 larvae are consumed by copepods completing the cycle as they enter water.

    Guinea Worm Eradication Program

    • Focuses on surveillance (monitoring cases), safe water access (filtration practices), and host infection control (treatment & isolation).
    • Community involvement and awareness are crucial.

    Peculiar Epidemiology of Dracunculiasis in Chad

    • Identified a recent resurgence of cases after many years in Chad.
    • Discovered dog involvement as an intermediate host, which was not previously understood. Dogs became infected by consuming copepods.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Explore the fascinating world of Nematoda, or roundworms, known for their unique characteristics such as tough cuticles and high body fluid pressure. This quiz covers their anatomy, reproduction, and ecological diversity, highlighting their role in various habitats. Dive into the key features that distinguish this phylum from others!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser