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VI. Viral Diseases

VI. Viral Diseases. A. Influenza B. Diseases Caused by the Herpes Family C. Viral Hepatitis D. Human Immunodeficiency Virus E. Miscellaneous Viral Diseases. VI. A. Influenza. Properties Member of the Orthomyxovirus family Enveloped RNA virus Two envelope proteins

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VI. Viral Diseases

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  1. VI. Viral Diseases A. Influenza B. Diseases Caused by the Herpes Family C. Viral Hepatitis D. Human Immunodeficiency Virus E. Miscellaneous Viral Diseases

  2. VI. A. Influenza • Properties • Member of the Orthomyxovirus family • Enveloped RNA virus • Two envelope proteins • Hemagglutinin and Neuraminidase • Segmented RNA • 8 segments; packaged into helical nucleocapsids • Antigenic variation & genetic exchange lead to the appearance of new strains; requires use of different vaccine combinations each year

  3. VI. A. Influenza • Symptoms & Complications of Influenza • Respiratory Tract Symptoms • Fever • Neurological Complications: • Guillain-Barré Syndrome • Reye’s Syndrome

  4. VI. B. Diseases Caused by the Herpes Family • Properties of the Herpes Virus Family • Large, enveloped DNA viruses • Icosahedral capsids • DNA replicates in the nucleus of host cells • Cells may become permanently infected • Host chromosomes may be altered • Herpes infections associated with certain cancers

  5. VI. B. Diseases Caused by the Herpes Family • Herpes Simplex • Two major strains • Type I: Oral Herpes • Type II: Genital Herpes • Skin lesions form at site of the infection • Virus travels along sensory neurons to ganglia, where it remains • During times of stress or weakened immunity, virus may travel along same neurons to re-infect the initial skin sites

  6. VI. B. Diseases Caused by the Herpes Family • Herpes Simplex (cont.) • Other complications • Herpes encephalitis • Congenital herpes • Cervical cancer • Treatment: Acyclovir

  7. VI. B. Diseases Caused by the Herpes Family • Chicken pox & Shingles • Cause: Varicella-zoster virus • Chicken pox symptoms • Shingles symptoms • Treatment • Chicken pox vaccine • Connection to Reye’s syndrome

  8. VI. B. Diseases Caused by the Herpes Family • Infectious mononucleosis • Cause: Epstein-Barr virus • Infectious mononucleosis • Lymph node swelling; fever; fatigue • Heterophile antibody production • Monospot Test • Other complications • Burkitt's Lymphoma • Chronic Fatigue Syndrome??!?

  9. VI. B. Diseases Caused by the Herpes Family • Cytomegalovirus • Mild symptoms in otherwise healthy individuals • Major complications • Miscarriages when contracted during pregnancy • Severe infections in AIDS patients • Major cause of blindness in AIDS patients

  10. VI. C. Viral Hepatitis • Hepatitis A • Also known as: • Infectious hepatitis • Short-incubation hepatitis • Viral Properties • Picornavirus Family • Small nonenveloped RNA viruses • Family includes common cold (rhinovirus) & polio viruses

  11. VI. C. Viral Hepatitis • Hepatitis A (cont.) • Transmission: • Virus particles are present in the stool • Fecal-oral route via contaminated food or water • Saliva contact, sexual contact, and arthropods also have been implicated

  12. VI. C. Viral Hepatitis • Hepatitis A (cont.) • Symptoms: • Two to four week incubation period • Nausea, vomiting, fever • Abdominal pain • Jaundice in many but not all cases • Duration usually several weeks

  13. VI. C. Viral Hepatitis • Hepatitis A (cont.) • Treatment & Prevention: • Prolonged rest • Hepatitis A Immune Globulin • Hepatitis A vaccine

  14. VI. C. Viral Hepatitis • Hepatitis B • Also known as: • Serum hepatitis • Long-incubation hepatitis

  15. VI. C. Viral Hepatitis • Hepatitis B (cont.) • Viral properties: • Hepadnavirus family • Nucleocapsid consists of DNA surrounded by hepatitis B core antigen (HBcAg) • The core is surrounded by a lipoprotein envelope containing the hepatitis B surface antigen (HBsAg) • The virus has also been called the Dane particle • Large amounts of excess HBsAg are found in the serum & may be detected serologically

  16. VI. C. Viral Hepatitis • Hepatitis B (cont.) • Transmission: • Contact with infected body fluids • Blood, blood products, semen, vaginal secretions (urine, saliva also implicated)

  17. VI. C. Viral Hepatitis • Hepatitis B (cont.) • Symptoms: • Incubation period: four weeks - six months • Nausea, fever • Dark urine & clay-colored stools • Abdominal tenderness • Jaundice • Duration of symptoms: 3 - 4 months • About 10% of patients remain carriers for several months

  18. VI. C. Viral Hepatitis • Hepatitis B (cont.) • Treatment & prevention • Hepatitis B Immune Globulin • Hepatitis B vaccination

  19. VI. C. Viral Hepatitis • Non-A non-B (NANB) Hepatitis • Hepatitis C • NANB serum hepatitis • Enveloped virus of the Flavivirus family • Transmission & symptoms similar to B • Delta hepatitis • A small defective RNA virus that requires coinfection with Hepatitis B to replicate • Co-transmitted with Hepatitis B

  20. VI. C. Viral Hepatitis • Non-A non-B (NANB) Hepatitis (cont.) • Hepatitis E • NANB infectious hepatitis • A small nonenveloped RNA virus of the calcivirus family • Transmission & symptoms similar to Hepatitis A

  21. VI. D. Human Immunodeficiency Virus • Viral Properties • A retrovirus • An enveloped RNA virus that replicates through a DNA intermediate • The DNA intermediate is synthesized by reverse transcriptase: an enzyme that makes a DNA molecule using an RNA template • The DNA intermediate is spliced into host chromosomes, making the infection permanent

  22. VI. D. Human Immunodeficiency Virus • Viral Properties (cont.) • Host cells for HIV: CD4+ cells • Helper T (T-4) lymphocytes • Macrophages • Damage to the helper T cell population cripples the immune system of the host

  23. VI. D. Human Immunodeficiency Virus • Transmission • Contact with infected body fluids • Blood, blood products, semen, vaginal secretions, breast milk

  24. VI. D. Human Immunodeficiency Virus • What is the difference between HIV & AIDS? • HIV: the Human Immunodeficiency Virus • The cause of AIDS • Also known as: HTLV-III and LAV • Two known types: HIV-1 and HIV-2 • AIDS: Acquired Immune Deficiency Syndrome • Catastrophic immune system failure caused by HIV infection • Symptoms & cases are usually defined by the CDC case surveillance definition

  25. VI. D. Human Immunodeficiency Virus • CDC Case Surveillance Definition for AIDS • Based on: • Clinical Symptoms: Categories A, B, C • Helper T-4 lymphocyte count: Categories 1, 2, 3 • Category A • Asymptomatic HIV infection • Persistent Generalized L ymphadenopathy • Acute HIV infection

  26. VI. D. Human Immunodeficiency Virus • CDC Case Surveillance Definition for AIDS (cont.) • Category B • Symptomatic HIV infection with constitutive illness & certain opportunistic infections • Often an early indication that AIDS is developing • *Category C • Symptomatic HIV infection with opportunistic infections listed in the CDC surveillance case definition

  27. VI. D. Human Immunodeficiency Virus • CDC Case Surveillance Definition for AIDS (cont.) • Category 1 • T-4 count greater than 400 per microliter of blood • Category 2 • T-4 count between 400 and 200 per microliter of blood • *Category 3 • T-4 count less than 200 per microliter of blood

  28. VI. D. Human Immunodeficiency Virus • CDC Case Surveillance Definition for AIDS (cont.) • *These categories (C and 3) meet the CDC surveillance definition to be included among the AIDS cases • Many HIV-infected individuals show no symptoms, yet are capable of transmitting the virus

  29. VI. D. Human Immunodeficiency Virus • Symptoms & Secondary Infections Associated with AIDS • Acute Infection • Fever, lymph node swelling, aches, fatigue, “flu-like” or “mono-like” symptoms • Persistent Generalized Lymphadenopathy • Lymph node swelling for greater than 6 months in two or more body areas (excluding the groin) • Often an early manifestation that AIDS has developed

  30. VI. D. Human Immunodeficiency Virus • Symptoms & Secondary Infections Associated with AIDS (cont.) • Constitutive Illness • Weight loss, persistent fever, diarrhea • Cancers • Kaposi’s sarcoma • Certain lymphomas

  31. VI. D. Human Immunodeficiency Virus • Symptoms & Secondary Infections Associated with AIDS (cont.) • Bacterial Secondary Infections • Mycobacterium • Listeria • Salmonella • Mycoplasma • many others

  32. VI. D. Human Immunodeficiency Virus • Symptoms & Secondary Infections Associated with AIDS (cont.) • Fungal Secondary Infections • Candida and others • Protozoan Secondary Infections • Toxoplasma gondii • Cryptosporidium • Pneumocystis carinii

  33. VI. D. Human Immunodeficiency Virus • Symptoms & Secondary Infections Associated with AIDS (cont.) • Viral Secondary Infections • Herpes simplex • Cytomegalovirus • Many others • Treatments • Inhibitors of DNA replication • Protease Inhibitors

  34. VI. E. Miscellaneous Viral Diseases • Miscellaneous Pneumotrophic Viruses • Rhinovirus • Adenovirus • Respiratory Syncytial Virus

  35. VI. E. Miscellaneous Viral Diseases • Miscellaneous Dermotrophic Viruses • Measles (Rubeola) • Rubella • Mumps • Fifth disease • Papilloma (HPV)

  36. VI. E. Miscellaneous Viral Diseases • Miscellaneous Viscerotrophic Viruses • Enterovirus (Coxsackie & Echo Viruses) • Rotavirus • Norwalk Virus

  37. VI. E. Miscellaneous Viral Diseases • Miscellaneous Neurotrophic Viruses • Poliomyelitis • Rabies • Arbovirus • Arenavirus (lymphocytic choriomeningitis)

  38. VI. E. Miscellaneous Viral Diseases • Prion Diseases • Bovine Spongiform Encephalopathy • Scrapie • Creutzfelt-Jakob Syndrome • Kuru

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