7/12/12

1

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

7/12/12

2

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

7/12/12

3

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

7/12/12

4

Enterobius vermicularis = pinworm Trichinella trichinosis

dead end host

Filarial worms: microfilariae

Wucheria

Dracunculus medinensis = guinea worm

Rod of Asclepias

caduceus

7/12/12

5

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

7/12/12

6

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)