\ helminthes mohanbio

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\ helminthes mohanbio

  1. 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. 2. The Helminths Table 12.1
  3. 3. Pathogenic Helminths (Worms) • Pathogenic helminthes belong to: • Flatworms (Phylum Platyhelminthes) • Roundworms (Phylum Nematoda/Aschelminthes)
  4. 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. 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. 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. 7. Lung fluke (Paragonimus westermanii) Intermediate hosts: snail, then crayfish or crab Definitive host: human Fluke (Trematode) Flatworm
  8. 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. 9. Shistosomiasis or Blood Fluke (Shistosoma) Blood fluke Flatworm (Platyhelminthes) Intermediate host: snail Definitive host: human
  10. 10. Beef/Pork Tapeworms (Cestode in Platyhelminthes) Intermediate host: pig or cow Definitive host: human Figure 12.27
  11. 11. Humans as Intermediate Host: Tapeworm Figure 12.28
  12. 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. 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. 14. Aschelminthes (Nematodes): Roundworms Nematodes: Eggs Infective for Humans Figure 12.29
  15. 15. Pinworm/Threadworm (Enterobius vermicularis) Egg infective roundworm
  16. 16. Ascaris worm (Ascaris sp.) egg infective roundworm
  17. 17. Hookworm (Necator americanus) larva infective roundworm
  18. 18. Trichinosis (Trichinella spiralis) larva infective roundworm
  19. 19. Nematodes: Larvae Infective for Humans Figure 25.26
  20. 20. Making a Table to Study and Associate Characteristics Species Helminth Group and Subgroup Disease Name Disease description Reproduction Hosts Sketch
  21. 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. 22. Arthropods as Vectors Figure 12.33

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