Invertebrate Zoology

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Invertebrate Zoology

• Lecture 13 Phylum Nematoda, Part 2
• Parasitic Life Histories

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Parasitic Life Cycles 1 Single host with a
free-living stage.

• Example hookworms
• Overview
• Common intestinal parasites
• Affect 25 of the human population
• Primarily in the tropics
• Common in dogs, cats and other mammals
• Symptoms
• Severe anemia
• Skin infections

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Hookworm life cycleSee additional details in
text
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Parasitic Life Cycles 2 Single host, direct
host-host transmission

• Example trichina worms (Trichinella spp.)
• Overview
• Humans infected by eating raw or undercooked
  pork.
• May be the reason for religious bans against pig
  products.
• Symptoms
• Excruciating pain and fever from larval burrowing
  into muscles

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Trichina worm life cycle
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Parasitic Life Cycles 3 Filarial nematodes
w/arthropod intermediate host

• Example Onchocerca volvulus (river blindness)
• Overview
• Prevalent in Africa
• Symptoms
• Subcutaneous lesions, including lesions of the
  eye that cause blindness

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Onchocerca volvulus life cycle