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VI. A. B. C. D. E. Viral Diseases Influenza Diseases Caused by the Herpes Family Viral Hepatitis Human Immunodeficiency Virus Miscellaneous Viral Diseases 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 VI. A. Influenza • Symptoms & Complications of Influenza – Respiratory Tract Symptoms – Fever – Neurological Complications: • Guillain-Barré Syndrome • Reye’s Syndrome 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 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 VI. B. Diseases Caused by the Herpes Family • Herpes Simplex (cont.) – Other complications • Herpes encephalitis • Congenital herpes • Cervical cancer – Treatment: Acyclovir 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 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??!? 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 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 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 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 VI. C. Viral Hepatitis • Hepatitis A (cont.) – Treatment & Prevention: • Prolonged rest • Hepatitis A Immune Globulin • Hepatitis A vaccine VI. C. Viral Hepatitis • Hepatitis B – Also known as: • Serum hepatitis • Long-incubation hepatitis 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 VI. C. Viral Hepatitis • Hepatitis B (cont.) – Transmission: • Contact with infected body fluids • Blood, blood products, semen, vaginal secretions (urine, saliva also implicated) 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 VI. C. Viral Hepatitis • Hepatitis B (cont.) – Treatment & prevention • Hepatitis B Immune Globulin • Hepatitis B vaccination 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 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 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 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 VI. D. Human Immunodeficiency Virus • Transmission – Contact with infected body fluids – Blood, blood products, semen, vaginal secretions, breast milk 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 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 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 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 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 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 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 VI. D. Human Immunodeficiency Virus • Symptoms & Secondary Infections Associated with AIDS (cont.) – Bacterial Secondary Infections • Mycobacterium • Listeria • Salmonella • Mycoplasma • many others 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 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 VI. E. Miscellaneous Viral Diseases • Miscellaneous Pneumotrophic Viruses – Rhinovirus – Adenovirus – Respiratory Syncytial Virus VI. E. Miscellaneous Viral Diseases • Miscellaneous Dermotrophic Viruses – – – – – Measles (Rubeola) Rubella Mumps Fifth disease Papilloma (HPV) VI. E. Miscellaneous Viral Diseases • Miscellaneous Viscerotrophic Viruses – Enterovirus (Coxsackie & Echo Viruses) – Rotavirus – Norwalk Virus VI. E. Miscellaneous Viral Diseases • Miscellaneous Neurotrophic Viruses – – – – Poliomyelitis Rabies Arbovirus Arenavirus (lymphocytic choriomeningitis) VI. E. Miscellaneous Viral Diseases • Prion Diseases – – – – Bovine Spongiform Encephalopathy Scrapie Creutzfelt-Jakob Syndrome Kuru