11/4/13

1

The Eukaryotes 5d: Animals

Helminths & Arthropods

Helminths: worms 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/HTML/Para_Health.htm

Phylum Platyhelminthes = flat worms Class Cestoda = tapeworms 2 body parts

hermaphroditic

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2

Taenia saginata = beef tapeworm (undercooked beef)

T. solium = pig tapeworm (undercooked pork or eggs) cysticercus = immature form in muscle

23.24

Def. host

Diphyllobothrium latum = broad fish tapeworm

Def. host

Phylum Platyhelminthes = flat worms Class Trematoda = flukes snails are usually the intermediate hosts

Humans are not always the definitive hosts

usually hermaphroditic except schistosomes

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3

Schistosoma = blood fluke Infects >200 million people/year

2 sexes

Swimmer’s itch (definitive hosts are birds)

Cercaria in skin

Fasciola = sheep liver fluke (Def. host: sheep & other grazing animals; humans are “accidental”)

hermaphroditic

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4

Phylum Nematoda = round worms

hookworms: Necator & Ancylostoma

Ascaris = common round worm

Enterobius vermicularis = pinworm

“scotch tape test”

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5

Trichinella trichinosis

dead end host

Filarial worms: microfilariae

Wucheria

Dracunculus medinensis = guinea worm

Rod of Asclepias

caduceus

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6

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

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7

Considered “diseases”

Sarcopti scabiei = scabies, sarcoptic mange Can be STI

Lice:

Pediculus spp.

Phthirus pubis = crab/pubic louse

Pediculus capitis

Demodex: commensal mite

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8

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.

(Note: 2 & 3 are currently debated)

(maggot)