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The Eukaryotes 12d: Animals
Helminths & Arthropods
Helminths reduced or no digestive system
reduced nervous system
no or reduced locomotion
life cycle is usually complex
For the CDC versions of parasite life cycles
http://www.dpd.cdc.gov/dpdx/Default.htm
Phylum Platyhelminthes = flat worms Class Cestoda = tapeworms
2 body parts
hermaphroditic
23.16
Taenia saginata = beef tapeworm (undercooked beef)
T. solium = pig tapeworm (undercooked pork or eggs)
cysticercus = immature form in muscle
Def. host
23.14
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Echinococcus granulosus
Diphyllobothrium latum = broad fish tapeworm
Def. host
Phylum Platyhelminthes = flat worms
Class Trematoda = flukes
snails are usually the intermediate hosts
usually hermaphroditic except schistosomes
23.19
23.20
Humans are not always the definitive hosts
Schistosoma = blood fluke Infects >200 million people/year
2 sexes
23.20
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Swimmer’s itch (definitive hosts are birds)
Cercaria in skin
Fasciola = sheep liver fluke (Def. host: sheep & other grazing animals; humans are “accidental”)
hermaphroditic
23.19
Phylum Nematoda
hookworms: Necator & Ancylostoma
Ascaris = common round worm
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Enterobius vermicularis = pinworm Trichinella trichinosis
dead end host
Filarial worms: microfilariae
Wucheria
Dracunculus medinensis = guinea worm
Rod of Asclepias
caduceus
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Anisakine worms: Anisakis & others
(~2 cm long)
Def. host
Phylum: Annelida (segmented worms)
Class: Hirudinae (leeches)
Hirudo medicinalis FDA approved
leech jar
Arthropod vectors (23.24)
Arachnids
Insects
Considered “diseases”
Sarcopti scabiei = scabies, sarcoptic mange Can be STI
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Lice:
Pediculus spp.
Phthirus pubis = crab/pubic louse
Pediculus capitis Maggot therapy - for treating non-healing wounds (FDA approved)
Blowflies (Calliphoridae)
usual species: Phaenicia sericata (green blowfly)
1. They clean the wounds by dissolving dead
and infected tissue ("debridement");
2. They may disinfect the wound (kill bacteria);
3. They may speed the rate of healing.
(these last 2 are currently debated)
(maggot)