Nematoda

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Nematoda
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Pseudocoelomates
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Common Characteristics

• Pseudocoel
• Mesoderm muscle lined ectoderm
• Complete digestive tract
• Organs are within pseudocoel
• Syncytial epidermis with non-living cuticle

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Coelom
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Phylum Nematoda

• Found everywhere
• Use pseudocoel as a hydrostatic skeleton
• Collagen cuticle
• Longitudinal muscles
• Free living and parasites
• Dioecious

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Nematode Body Plan
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Muscle Structure

• Longitudinal muscles
• Parallel to ventral and dorsal nerve cords
• Muscle cells form processes to associate with
  nerve cells
• Muscles act against the hydrostatic skeleton

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Muscle/Nerve Structure
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Digestion and Metabolism

• Pharynx
• Radial muscles
• Intestine
• Single cell layer with no muscles
• Body movement and ingestion moves food
• Parasitic nematodes often lack complete aerobic
  respiration

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Nematode Parasites

• Ascaris (roundworms)
• Found in intestine and lung.
• Hookworms
• Attach to intestine and suck blood.
• Trichina worm
• Forms cysts in muscle
• Causes trichinosis
• Pinworms
• Males are haploid, females diploid
• Live in large intestine
• Filarial worms
• Live in lymphatic system

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Caenorhabditis elegans

• Extensively using in genetic and animal
  development research
• Lineage of each cells is know and documented
• Whole genome is cloned and sequenced

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Family Ancylostomidae

• Hookworm
• Ancylostoma duodenale
• Necator americanus
• Ancylostoma caninum

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Ancylostoma cutting teeth
Ancylostoma caninum
Necator americanus
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Male Copulatory Bursa
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Ancylostomidae larval forms
Rhbaditiform larva
Filariform larva infective form
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Ancylostomidae
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Family Ascarididae

• Humans
• Ascaris lumbricoides
• Pigs
• Ascaris suum
• Cats
• Toxocara cati
• Dogs
• Toxocara canis
• Cats and Dogs
• Toxocara leonina

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Ascaris lumbricoides
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Ascaris Egg Development
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Toxocara canis
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Toxocara in situ

• Visceral organ migrans in intermediate host
  (rodent).
• Visceral organ migrans in humans is a dead end
  infection.

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Toxocara cati

• Adults in intestine
• Heavy infection can cause intestinal blockage

Toxocara cati
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Toxocara cati
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Toxocara transmission to young

• Toxocara cati
• transmammary route to kittens.
• Toxocara canis
• transplacental to fetus and transmammary route to
  puppies.

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Strongyloides sterocoralis

• Homogonic cycle
• Female is parasitic
• Parthenogenesis
• Heterogonic cycle
• Free living worms can mate in soil

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Strongyloides stercoralis
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Enterobius vermicularis

• Pinworm
• Not very pathogenic only discomfort
• Do not infect dogs or cats
• Feed on epithelial cells and bacteria in
  intestine
• Males are haploid, females diploid

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Enterobius vermicularis
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Male and Female Pinworms
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Flat sided pinworm eggs
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Dirofilaria immitis

• Dog and cat heart worm
• Transmitted through mosquitoes
• Most common in dogs
• Infects heart and lungs

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Dirofilaria immitis in blood
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Dirofilaria immitis in heart
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(No Transcript)
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Wuchereria bancrofti

• Causes Elephantitis
• Swelling and blockage of lymph ducts cause
  massive swelling in late stages

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Trichinella spp.

• Domestic cycle
• Pigs
• Trichinella spiralis
• Sylvatic cycle (hunting and eating wild mammals)
• Temerate Zone
• Trichinella britovi
• Trichinella spiralis
• Trichinella murrelli
• Tropic Zone
• Trichinella nelsoni
• Arctic Zone
• Trichinella nativa

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Trichinella spiralis
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Trichinella spiralis in situ
Muscle
Blood
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Phylum Acanthocephala

• Absorb nutrients through tegument
• Infect livestock, dogs and cats
• Requires invertebrate intermediate host
• For example beetle grubs are the intermediate
  host for pig infection

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• Proboscis
• Everts and attaches to intestine