Transcript Influenza
Virion Structure and Organization • RNA envelope virus •Endemic in waterfowl; epidemic in humans •Genome composed of eight RNA segments (7 in influenza C) •Proteins hemaggluttinin (HA) and neurominidase (NA); 17 H and 10 N •Influenza C structurally different, compositionally similar Copycat virus: Rhinovirus ; RSV History The “Spanish Flu” of 1918 •Killed as many as 25 million in the first 25 weeks, whereas HIV/AIDS killed 25 million in the first 25 years •Killed ~5% of human population Infection and Replication Three Types/Naming the Virus Type Symptoms Epidemic Vaccine Genetic Drift Genetic Shift Pandemic Animals A (most common) Resp/Cons tit. yes yes yes yes yes Birds. Pigs. Horses. dogs B Resp/Cons tit. yes yes yes no no no C Resp no no yes no no Pigs, dogs •H- something, N-Something •Standard Nomenclature •Type (family), species isolated from (if non-human), location, isolate #, isolate yr, HA/NA subtype •A/Panama/2007/1999 (H3N2) Evolution of Influenza 1. Antigenic Shift 1. Antigenic drift Symptoms and Diagnosis •Abrupt •3-7 days •Respiratory •Stuffy nose •Sore throat •cough •Constitutional •Fever/chills •Body aches •fatigue CDC definition (Influenza-like illness ILI): sore throat or cough AND fever Quick way to distinguish cold from flu •Cold viruses don’t have constitutional symptoms Treatment •Testing for Flu •Don’t usually test unless 1. need for further testing 2. to figure out what kind of medication to prescribe 3. need to know the type for infection control •Rapid Test •Antiviral Drugs for Influenza •Amantadine and Rimantadine block M2 •Oseltamivir (pill) and Zanamiver (powder) block Neuraminidase (NA)– Age Restriction Why treat patient? •High risk •<2 yo , > 65 yo •Pregnant •Chronic Disease (weak immune system) • Severe Disease/ hospitalization Prevention 1. 2. 3. 4. Wash hands Don’t touch your face Avoid sick people Vaccine University of Michigan Placebo vs. dead virus VE (Vaccine Efficacy) 60%-70% 2014 VE= 61% According to the CDC TIV and LAIV Vaccines Making Flu Vaccine Steps Strain (WHO) Manufacturing Eggs (millions) safety (FDA) Distribution Clinics YOU! Flu Surveillance •Hospitalized per year (global): 3,000,000-5,000,000 ; (US) 200,000 •Die per year (global): 250,000-500,000 ; (US) 3,000-49,000 Weekly US MAP (CDC) Flu Doctor HospitalCounty StateUS (Atlanta) Total Searches % each day (ILI) Flu Searches Upper Respiratory area Lower Respiratory area Current Research How to prevent new pandemics of influenza viruses—H5N1 outbreak Some H5N1 viruses are adhesive to human upper respiratory tissue Study showed that bronchiolar area may be site of viral receptor specificity change To prevent pandemic, must stop avian human transmission and get rid of prolonged infection of patient References Ahmed R, Oldstone MB, Palese P. Protective immuniity and susceptibility to infectious diseases: lessons from the 1918 influenza pandemic. Nature Immunol 2007; (March 17): 1188-1193 Bouvier NM, Palese P. The Biology of influenza viruses. Vaccine 2008 (March 17): D49- D53 Centers for Disease Control and Prevention. (2014) Seasonal Influenza (Flu). Retrieved from http://www.cdc.gov/flu/ Shinya,K. et al. Avian flu: influenza virus receptors in the human airway. Nature 440, 435436 (2006). Stegmann T. Membrane fusion mechanisms: the influenza hemagglutinin paradigm and its implications for intracellulare fusion. Traffic 2000; 1 (March 20): 598-604 Uyeki T: Human Infection with Highly Pathogenic Avian Influenza (H5N1) Virus: Reviews of Clinical Issues. (2009) Clinical Infectious Diseases : 279-290 Retrieved from http://cid.oxfordjournals.org/content/49/2/279.long World Health Organization. (2014) Health topics: Influenza. Retrieved from http://www.who.int/topics/influenza/en/