Nematodes Characteristics: Phylum Nematoda Quiz and Flashcards

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Questions and Answers

What is the primary characteristic of the Phylum Nematoda, or roundworms?

They have an extracellular lifestyle

They have a bursa, spicules, and testes in the male, and a vulval flap in the female

They have a spaghetti-like, round elongated cylindrical shape (correct)

They primarily infect the gastrointestinal tract, but can also infect other organs

How do nematodes typically survive and persist in the environment?

Nematodes have a paratenic host, such as a bird eating an intermediate host snail, to facilitate transmission

Nematodes have a periparturient rise, where egg production increases around the birth of young animals

Nematodes have a thick-shelled egg that can last for up to ten years, protecting the larvae (correct)

Nematodes release their larvae (L1) into the environment, which then develop into the infective L3 stage

What is the primary mode of infection for the nematode Ancylostoma caninum?

Ingestion of paratenic hosts, such as birds eating infected snails

Indirect infection through larvae (L1) in an intermediate host

Transplacental or transmammary transmission from mother to offspring

Direct infection through larvae (L3) in the environment (correct)

How can the level of nematode infection in a host be related to environmental exposure?

The level of infection is directly proportional to the amount of environmental exposure, as what is consumed is what lives in the host Signup and view all the answers

What is the diagnostic stage of Ancylostoma caninum infection in a live animal?

Eggs in the feces Signup and view all the answers

How can pasture nutrition and parasite management be balanced to control nematode infections?

By ensuring that the pasture provides adequate nutrition to the host, which can help the immune system fight off nematode infections Signup and view all the answers

What is the primary reason for the decreased immunity during pregnancy and birth?

To allow for the transmission of nematodes to the offspring Signup and view all the answers

Which of the following statements accurately describes the relationship between fecal counts and the number of worms?

Fecal counts are not always related to the number of worms, but rather to the worm mass. Signup and view all the answers

Which of the following stages of nematode development is considered the infective stage?

L3 (Third-stage larvae) Signup and view all the answers

What is the primary reason for the periparturient rise in nematode egg production during the spring (April-June)?

The mother's lowered immunity during the lambing season Signup and view all the answers

What is the purpose of the adult nematodes secreting a substance that forces new larvae to be passed or arrested during the fall-winter period?

To avoid competition with the existing nematode population Signup and view all the answers

Which of the following interventions is suggested for managing nematode infections in ruminants?

Moving pastures halfway through lambing to reduce exposure Signup and view all the answers

Study Notes

Phylum Nematoda: Roundworms

Roundworms have a spaghetti-like, round, elongated cylindrical shape.
They can be found in the GI tract, but some species can be found in other organs, where they are more pathogenic.
Males and females copulate permanently, staying attached, with males having testes, spicules, and some having a bursa.
Females have a vulval flap, or "finger-like appendage," and can be smooth or rough.

Life Cycle and Development

The life cycle involves indirect and direct hosts, with larvae in the environment, and L3 larvae in the definitive host.
The diagnostic stage involves eggs in feces, and autopsy reveals adult worms.
Egg hatches in the environment, and the egg may be infective with L2 or L3 larvae.
Paratenic hosts, like birds eating infected snails, can transfer the infection.

Infection and Pathology

The level of infection is related to environmental exposure, with grazing animals being more susceptible.
Primary clinical signs and primary modes of infection are important to understand, as well as the relationship between morphology, behavior, and pathology.
Ancylostoma caninum is an example of a species with distinct clinical signs and modes of infection.

Survival and Transmission

Nematodes can survive on pasture, but some may arrest development in the host.
Temperature affects the survival and development of certain species, with some thriving in colder or hotter climates.
Climate change has led to an expansion of range for some species, such as H. contortus.

Immunity and Control

Immunity decreases during pregnancy and birth, and the "periparturient rise" is a phenomenon where egg production increases around birth.
Avoiding the immune system, crowding, and "bad weather" can lead to arrested development or hypobiosis.
Intervention methods include moving pastures, increasing dietary protein, and treating mothers to reduce exposure.

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Description

Test your knowledge on the key characteristics of Phylum Nematoda, focusing on roundworms. Explore topics such as GI tract dwelling, unique shapes, mating behaviors, and the impact of environmental exposure on infection levels.

Phylum Nematoda and Roundworms Key Characteristics Quiz