1. Eukaryotic Pathogens: Helminthes What types of eukaryotic organisms are pathogenic, and how do they differ from bacteria?
Helminthes (The Worms)
Specializations of Animal Parasites
Flatworms (Platyhelminthes)
Flukes and tapeworms
Roundworms (Aschelminthes/Nemtodes)
Egg infective: pinworm, ascaris
Larvae infective: hookworm, trichinella
Eukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

2. The Helminths
Table 12.1

3. Pathogenic Helminths (Worms)
Pathogenic helminthes belong to:
Flatworms (Phylum Platyhelminthes)
Roundworms (Phylum Nematoda/Aschelminthes)

4. Pathogenic Helminths (Worms)
Pathogenic helminthes belong to:
Flatworms (Phylum Platyhelminthes)
Roundworms (Phylum Nematoda/Aschelminthes)
As parasites, they have:
Little or no digestive system
A very simple nervous system
Little or no means of locomotion
A complex reproductive system, sometimes with multiple
hosts (definitive and intermediate)

5. Pathogenic Helminths (Worms)
Pathogenic helminthes belong to:
Flatworms (Phylum Platyhelminthes)
Paragonimus westermanii - paragonimiasis (lung fluke)
Shistosoma - shistosomiasis (blood fluke)
Taenia sp. - beef/pork tapeworm
Roundworms (Phylum Nematoda/Aschelminthes)
Enterobium vermicularis -pinworm/threadworm infection
Ascaris- ascariasis
Necator americanus - hookworm infection

6. Flatworm Characteristics
General Characteristics
Flattened shape
Incomplete gut
Same individual makes both
sperm and eggs (monoecious)
Divided into two groups:
Flukes (Trematoda)
Suckers on ventral surface
Tapeworms (Cestodes)
Barbed scolex “head”
Proglottid segments

7. Lung fluke (Paragonimus westermanii)
Intermediate hosts: snail, then crayfish or crab
Definitive host: human
Fluke (Trematode) Flatworm

8. Humans as Definitive Host: Lung Fluke (A Trematode)
Intermediate hosts: snail, then crayfish or crab
Definitive host: human
Lung fluke: Paragonimus westermanii
Figure 12.26

9. Shistosomiasis or Blood Fluke (Shistosoma)
Flatworm (Platyhelminthes)
Intermediate host: snail
Definitive host: human

10. Beef/Pork Tapeworms (Cestode in Platyhelminthes)
Intermediate host: pig or cow
Definitive host: human
Figure 12.27

11. Humans as Intermediate Host: Tapeworm
Figure 12.28

12. Pathogenic Helminths (Worms)
Pathogenic helminthes belong to:
Flatworms (Phylum Platyhelminthes)
Paragonimus westermanii - paragonimiasis (lung fluke)
Shistosoma - shistosomiasis (blood fluke)
Taenia sp. - beef/pork tapeworm
Roundworms (Phylum Nematoda/Aschelminthes)
Enterobium vermicularis -pinworm/threadworm infection
Ascaris- ascariasis
Necator americanus - hookworm infection

13. Roundworm Characteristics
General characteristics
Cylindrical shape
Tapered ends
Complete gut
Different individuals for difft
genders (dioecious)
Divided into two groups:
Egg infective roundworms
Larva infective roundworms

14. Aschelminthes (Nematodes): Roundworms
Nematodes: Eggs Infective for Humans
Figure 12.29

15. Pinworm/Threadworm (Enterobius vermicularis)
Egg infective roundworm

16. Ascaris worm (Ascaris sp.)
egg infective roundworm

17. Hookworm (Necator americanus)
larva infective roundworm

18. Trichinosis (Trichinella spiralis)
larva infective roundworm

19. Nematodes: Larvae Infective for Humans
Figure 25.26

20. Making a Table to Study and Associate Characteristics
Species
Helminth Group and Subgroup
Disease Name
Disease description
Reproduction
Hosts
Sketch

21. Arthropods as Vectors Kingdom: Animalia
Phylum: Arthropoda (exoskeleton, jointed legs)
Class: Insecta (6 legs)
Lice, fleas, mosquitoes
Class: Arachnida (8 legs)
Mites and ticks
May transmit diseases (vectors)
Figure 12.31, 32

22. Arthropods as Vectors
Figure 12.33