1 / 24

Influenza Today

Influenza Today. Joseph Mester, Ph.D. September 24, 2009. Control of Infectious Diseases. Control of Infectious Diseases. Sanitation Diagnosis Antimicrobials Vaccines Still, an ongoing effort. Influenza Surveillance: CDC & WHO.

marisela-nonnie
Download Presentation

Influenza Today

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Influenza Today Joseph Mester, Ph.D. September 24, 2009

  2. Control of Infectious Diseases

  3. Control of Infectious Diseases • Sanitation • Diagnosis • Antimicrobials • Vaccines • Still, an ongoing effort

  4. Influenza Surveillance:CDC & WHO • Monitor prevalence of circulating strains and detect new strains • Rapidly detect outbreaks • Assist disease control through rapid preventive action • Estimate influenza-related morbidity, mortality and economic loss

  5. On the Web • http://www.flu.gov/ • http://www.cdc.gov/H1N1FLU/ • http://www.fda.gov/NewsEvents/PublicHealthFocus/ucm150305.htm

  6. Influenza Virus:Morbidity and Mortality • Debilitating illness lasting 5-7 days • Most severe when there is underlying cardiac or pulmonary disease • In the USA: • ~150,000 influenza-associated hospitalizations per year • ~7,000-70,000 average deaths per year • Up to 10x this number of deaths during pandemics • >500,000 (USA) and 20 Million deaths (world wide) in 1918 pandemic

  7. Influenza in the USA Glezen, Epidemiology Revs. 1996. 18:64-76

  8. Influenza Pathogenesis • Respiratory & contact transmission • Replication in respiratory epithelium with subsequent destruction of cells • Viremia rarely documented • Viral shedding in respiratory secretions for 5-10 days

  9. Virus Variables • Virulence of Strain(s) • e.g., H5N1 (pandemic) vs. H1N1 (seasonal) Influenza • Immune suppression? • Immune over-activation? • Tissue invasiveness • Speed of replication • Amount of necrosis • Dose • Co-infection / multiple infection

  10. Influenza Virus Strains • Type A- moderate to severe illness - all age groups - humans and other animals • Type B- milder epidemics - humans only - primarily affects children • Type C- rarely reported in humans - no epidemics

  11. Type of nuclear material Neuraminidase Hemagglutinin A/Moscow/21/99 (H3N2) Virus type Geographic origin Strain number Year of isolation Virus subtype Influenza Virus

  12. Enveloped RNA Virus • Capsid with helical symmetry • Polymorphic shape • Segmented Genome • 8 Negative sense RNAs InfluenzaVirus

  13. Influenza Virus Evolution • Genetic Variability • Virus is prone to accrue nucleotide misincorporations • error-prone viral RNA-dependent RNA polymerase with no proof-reading function • Misincorporation rate for Influenza A virus: • 1 x 10-4 - 10-5 changes/ nucleotide position/ replication cycle

  14. Antigenic Drift

  15. Replication in Animals(Other Than Man) • Agricultural Animals • - Hogs • - Horses • - Cattle • - Sheep • - Goats • - Chickens • - Turkeys • Aquatic/Wild Birds - Ducks - Geese - Quail - Pheasants • Companion Animals • - Dogs • - Cats

  16. Antigenic Shift: Reassortment

  17. Shift Timeline

  18. Triple-Reassortant Swine Influenza A (H1) 11 sporadic cases 2006-2008 NEJM 2009

  19. Pandemic Flu 1918 (H1N1) • 40 million deaths world-wide • 675,000 in US • Mortality 2.5% • Flu killed more than WWI (1918) • Estimated that half of the US WWI casualties were due to Flu Others 1957 Asian Flu (H2N2) 1968 Hong Kong (H3N2) 1976 Swine Flu (H1N1) 2009 Swine Flu (H1N1) Avian Flu’s 1997 H5N1 Hong Kong 1999 H9N2 Hong Kong 2004 H5N1 San Francisco

  20. Phases of the Immune Response to Influenza

  21. Influenza Vaccines • Inactivated subunit (TIV) • Intramuscular • Trivalent • Live attenuated vaccine (LAIV) • Intranasal • Trivalent

  22. Composition of the 2009-10 Seasonal Influenza Vaccine • A/Brisbane/10/2007 (H3N2) • A/Brisbane/59/2007 (H1N1) • B/Brisbane/60/2008

  23. VaccineAttenuation

  24. Influenza Antiviral Agents • Amantadine and rimantadine • effective against influenza A only • approved for treatment and prophylaxis • Zanamivir and oseltamivir • neuraminidase inhibitors • “generally” effective against influenza A and B • Most currently circulating seasonal influenza A strains are resistant! • oseltamivir approved for prophylaxis

More Related