1. Lecture 13: Phylum Nematoda, Part 2 Parasitic Life Histories
Invertebrate Zoology
Lecture 13: Phylum Nematoda, Part 2
Parasitic Life Histories

2. 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

3. Hookworm life cycle *See additional details in text

4. 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

5. Trichina worm life cycle

6. Example: Onchocerca volvulus (river blindness)
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

7. Onchocerca volvulus life cycle