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INTH 301/401 Fundamental Concepts in Global Health

INTH 301/401 Fundamental Concepts in Global Health. Ron Blanton CGHD, CWRU. Infectious Agents of Disease. Viruses Bacteria Parasites. Viruses. Acellular organisms Nucleic Acids Origins Employ host cellular machinery to make proteins, nucleic acid and new virus Do not divide

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INTH 301/401 Fundamental Concepts in Global Health

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  1. INTH 301/401 Fundamental Concepts in Global Health Ron Blanton CGHD, CWRU

  2. Infectious Agents of Disease • Viruses • Bacteria • Parasites

  3. Viruses • Acellular organisms • Nucleic Acids • Origins • Employ host cellular machinery to make proteins, nucleic acid and new virus • Do not divide • Do not generate/manipulate energy • Miniscule

  4. Negative strand RNA polymerase Ribosomes Viral Structure envelope protein coat (capsid) 0.01-0.1 μm DNA or RNA

  5. Classification • Disease • Transmission • Nucleic Acid • Sequence

  6. Classification • Disease • Cold • Hepatitis • Encephalitis • Hemorrhagic fever • Oncogenic • Transmission • Nucleic Acid • Sequence

  7. Classification • Disease • Transmission • Respiratory • Enterovirus • Arbovirus • Nucleic Acid • Sequence

  8. Classification • Disease • Transmission • Nucleic Acid • DNA • RNA • Sequence

  9. Nucleic Acid Classification

  10. Classification • Disease • Transmission • Nucleic Acid • Sequence • International Committee on Taxonomy of Viruses • 7 Genera DNA viruses • 15 Genera RNA viruses

  11. Classification Hemorrhagic Fever Viruses • Disease • Rift Valley Fever – Lassa, SAHF • Marburg, Ebola – Dengue, Yellow Fever • Nucleic Acid • RNA • Sequence • Bunyavirus – Arenavirus • Filovirus – Flavivirus

  12. Life cycle • Recognition - Receptor • Invasion • Transcription/translation or translation/transcription • Packaging • Release

  13. Receptor Flaviviral Replication Invading virion New virions Viral particle = virion RNA RNA Cell membrane Cap Proteases Cap Cap Cap Mature proteins Cap Cap

  14. Receptor Cap Cap Cap Cap Cap Cap Cap Cap Filoviral Replication Invading virion New virions Viral particle = virion RNA RNA Cell membrane Viral polymerase Protein synthesis

  15. Implications • Rapidly reproduced to high density • Mutation • Easily transported • Wide host range (sometimes) • Limited range of viral poisons • Many modes of transmission

  16. Viral Tramission • Respiratory Measles • Respiratory-oral Colds • Urine-Respiratory Hanta pulmonary syndrome • Fecal-oral Rotavirus diarrhea • Direct contact Chickenpox • Veneral HIV • Congenital Rubella • Zoonoses Congo-Crimean Hemorrhagic • Vector borne Dengue • Transfusion Cytomegalovirus

  17. Virus and Disease • Cytopathic effect • Inhibit DNA, RNA protein synthesis • Apotosis • Proliferation

  18. Viral Prevention/Treatment • Isolation (migration) • Host Response • Vaccination • Antivirals

  19. Infectious Agents of Disease • Viruses • Bacteria • Parasites

  20. Bacteria • Simple cells • Cell membrane and wall (and envelope) • Reproduction by division

  21. Bacterial Structure LPS http://pathmicro.med.sc.edu/fox/protype.htm

  22. Gram Staining Reveals Structure S. aureus E. coli http://www.buddycom.com/bacteria/gnc.html

  23. “Bacterial Genetics” • Bacteria & Archea • Eukaryotes • Plant • Yeast • Parasites • Insects • People

  24. Implications • “Rapidly reproduce” in the right context • Resistance • Persistance • Mutation/Gene transfer • Toxin production

  25. Bacterial Prevention/Treatment • Contact • Host response • Vaccines • Antimicrobials/Antibiotics

  26. Infectious Agents of Disease • Viruses • Bacteria • Parasites

  27. Parasites • Single cell or multicellular eukaryotes living within a larger • Complex developmental programs

  28. SYMBIOSIS Commensalism Mutualism Parasitism Conceptual Basis of Parasitism

  29. Host - Parasite Relationships • Definitive host = Sexual reproduction • Echinococcosis - dogs • Schistosomiasis - humans • Pork tapeworm - humans • Malaria - mosquito • Intermediate host = Asexual reproduction • Echinococcosis - humans • Schistosomiasis - snail • Pork tapeworm - humans • Malaria - humans

  30. Parasitism in Human Biology and Medicine • Parasite – usually refers to protozoa and helminths • Distinction from other classes of infectious agents (bacteria and viruses) – historical significance more than biological distinction • A ‘re-emerging’ cause of illness in industrialized nations. • Health impact greatest in developing nations and among impoverished people

  31. Classification • Eukayrotes – membrane-bound organelles • Complex developmental programs

  32. Helminths (Macroparasites) Chronic and persistent infections Disease related to intensity of infection Asymptomatic, chronic Aggregated distribution Protozoa (Microparasites) Usually acute and transient infections Disease initiated by small inoculum Asymptomatic, acute Distribution is random Epidemiology and Clinical Characteristics

  33. Parasitic Protozoa Single cell organisms Multiply in human host Organelles analogous to tissues or organ systems Apicomplexa Include chloroplast-like structures Malaria, toxoplasma Archezoa Lack mitochondria, anaerobic Amebae Giardia lamblia Kinetoplastida Single large mitochondria Trypanosomes Leishmania

  34. Multicellular Does not multiply in host Specialized organ systems Nematodes Round worms Platyhelminthes Flat worms Trematodes Flukes Cestodes Tapeworms Parasitic Helminths

  35. Transmission of Parasitic Diseases • Fecal-oral route – common for food-borne pathogens, including Giardia lamblia and Entameba histolytica (protozoa), many geohelminths including Ascaris, Trichuris, Taenia (tapeworm) and Enterobius (pinworm) • Vector-borne – includes mollusks (snails) and multiple arthropods (mosquitoes, black flies). Examples are schistosomes, lung flukes, filarial worms, leishmaniasis, trypanosomiasis, malaria • Note: Vectors are required for completion of parasite life cycles. Not simply a vehicle for transfer to mammalian host.

  36. Parasite Disease Mechanisms • Physical damage – invasion, attachment to tissues, tissue consumption, obstructions, parasite proteases and other products • Innate immune responses – TNF-a, other cytokine production • Immunopathology – host immune response leads to parasite containment coincidental with secondary tissue damage • Spectrum of disease modified by transmission (i.e. intensity/chronicity of exposure), parasite burden and innate factors (genetic, immunologic, developmental)

  37. Additional Courses Medicine • INTH 484: Geographic Medicine and Epidemiology • INTH 494: Infectious Disease Epidemiology • INTH 5001: Orientation to International Health • FAMD 5023: International Health Practice • IMMU 3002 Tuberculosis and AIDS • IMMU 3003: Tuberculosis and History • EPBI 592: Geographic Information Systems and Statistical Analysis of Spatial Data

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