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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)
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Eukaryotic Pathogens: HelminthesWhat 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.
The Helminths Table 12.1
Pathogenic Helminths (Worms) • Pathogenic helminthes belong to: • Flatworms (Phylum Platyhelminthes) • Roundworms (Phylum Nematoda/Aschelminthes)
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)
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
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
Lung fluke(Paragonimus westermanii) Intermediate hosts: snail, then crayfish or crab Definitive host: human Fluke (Trematode) Flatworm
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
Shistosomiasis or Blood Fluke(Shistosoma) Blood fluke Flatworm (Platyhelminthes) Intermediate host: snail Definitive host: human
Beef/Pork Tapeworms (Cestode in Platyhelminthes) Intermediate host: pig or cow Definitive host: human Figure 12.27
Humans as Intermediate Host: Tapeworm Figure 12.28
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
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
Aschelminthes (Nematodes): Roundworms Nematodes: Eggs Infective for Humans Figure 12.29
Pinworm/Threadworm(Enterobius vermicularis) Egg infective roundworm
Ascaris worm(Ascaris sp.) egg infective roundworm
Hookworm(Necator americanus) larva infective roundworm
Trichinosis(Trichinella spiralis) larva infective roundworm
Nematodes: Larvae Infective for Humans Figure 25.26
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
Arthropods as Vectors Figure 12.33