Selected Viral Diseases Updated March 2015 J. D. Hendrix

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

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

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

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

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

B.Diseases Caused by the Herpes Family Herpes Simplex (cont.) –Other complications Herpes encephalitis Congenital herpes –Treatment: Acyclovir

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

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??!?

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

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

C.Viral Hepatitis Hepatitis A (cont.) –Transmission: Virus particles are present in the stool Fecal-oral route via contaminated food or water

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

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

C.Viral Hepatitis Hepatitis B –Also known as: Serum hepatitis Long-incubation hepatitis

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

C.Viral Hepatitis Hepatitis B (cont.) –Transmission: Contact with infected body fluids Blood, blood products, semen, vaginal secretions

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: months About 10% of patients remain carriers for several months

C.Viral Hepatitis Hepatitis B (cont.) –Treatment & prevention Hepatitis B Immune Globulin Hepatitis B vaccination

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

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

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

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

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

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

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

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

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

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

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

E.Miscellaneous Viral Diseases Miscellaneous Pneumotrophic Viruses –Rhinovirus –Adenovirus –Respiratory Syncytial Virus

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

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

E.Miscellaneous Viral Diseases Miscellaneous Neurotrophic Viruses –Poliomyelitis –Rabies –Arbovirus –Arenavirus (lymphocytic choriomeningitis)

E.Miscellaneous Viral Diseases Prion Diseases –Bovine Spongiform Encephalopathy –Scrapie –Creutzfelt-Jakob Syndrome –Kuru