Published on March 27, 2008
Pandemic Influenza: Pandemic Influenza CAPT Lynn Slepski, RN, MSN, CCNS Senior Public Health Advisor Immediate of the Assistant Secretary Infrastructure Protection May 10, 2006 Objectives: Objectives Define Pandemic Define Avian Flu Contrast normal flu vs. pandemic flu Explore the current Avian Flu issue Answer your questions Background: Influenza : Background: Influenza Contagious respiratory disease caused by the influenza virus Occurs both in birds and mammals Typically remains specific to the species in which they occur Background: Influenza Virus: Background: Influenza Virus A globular particle (about 100 nm in diameter)—smallest unit of “life” Cannot “move” or replicate on its own Sheathed in a lipid bilayer (derived from the plasma membrane of its host) 8 RNA Molecules HA genes (Hemagglutinin) NA genes (Neuramidase) NP (Nucleoproteins) Variety of matrix, proteins, and polymerases 16 HA and 9 NA subtypes with 144 combinations possible Slide5: Avian Influenza Avian Influenza is an infection caused by avian (bird) influenza (flu) viruses Flu viruses occur naturally among birds worldwide Wild birds carry the viruses in their intestines, but usually do not get sick Easily transmitted to domesticated birds like chickens, ducks, and turkeys and usually acquire them by coming in contact with contaminated excretions—they usually die. May be transmitted to other species May mutate to cause human to human infections >300 million domestic poultry culled 186 human cases/ 105 fatalities 24 March 06 Human Influenza: Human Influenza Highly contagious, spread by coughing and sneezing Most dangerous to the very young, very old, immunocompromised and pregnant Most are endemic influenza viruses, adapted to humans Influenza A (H3N2, some H1N1), influenza B viruses Drift: genetic changes little-by-little each year – reason to change vaccine strains Pandemics – shift: abrupt replacement of gene segment (reassortment of 8 gene segments) 1918: Spanish Flu (H1N1) - ?AIV genes 1957: Asian Flu (H2N2) - 3 AI & 5 human flu genes 1968: HK Flu (H3N2) - 2 AI & 6 human flu genes Background: Disease Mechanism : Background: Disease Mechanism What is a Pandemic?: What is a Pandemic? An global epidemic that occurs when a new virus “emerges” in the human population Occurs over a very wide area (several countries or continents) Usually affects a large proportion of the population--very limited or no immune response What Makes an Influenza Pandemic?: What Makes an Influenza Pandemic? More cases than expected—widespread Sudden shift in strain Not expected (more pathogenic) No pre-existing immunity Duration Longer (up to 18 months) Multiple waves, each different May be some advance notice (not a lot) Medical infrastructure capacity compromised Effects of Past Pandemics on the U.S. : Effects of Past Pandemics on the U.S. All three spread around the world in less than a year after efficient sustained human-to-human transmission. The Seasonal or “Regular” Flu Centers for Disease Control and Prevention (CDC): The Seasonal or “Regular” Flu Centers for Disease Control and Prevention (CDC) Follows predicable patterns Caused by already circulating viruses Some immunity built up from previous exposures Usually healthy adults not at risk for serious complications “Normal” flu season about 226,000 Americans are hospitalized 36,000 die from the disease Most deaths occur among people older than 65 (90%) on average, 98 of every 100,000 seniors with the flu die. Prevention-competent vaccine & good hygiene practices Influenza costs the U.S. economy about $12 billion annually in direct medical costs and loss of productivity. As of March 18, 2006 103,188 cases “below average” Pandemic virus production in 2 steps:: Pandemic virus production in 2 steps: AI virus infection of humans – limited infections Sustained human-to-human transmission – reassortment (hybrid virus) Pandemic Strain Emergence: Direct Infection: Avian Reservoir Pandemic Strain Emergence: Direct Infection Avian virus Pandemic Strain Emergence: Reassortment of Influenza A Viruses: Avian Reservoir Avian virus Human virus Pandemic Strain Emergence: Reassortment of Influenza A Viruses Pandemic Challenges : Pandemic Challenges Pandemics are different from other emergencies because it’s likely that almost all locations will be affected simultaneously Resources cannot be shifted geographically as in other emergencies Every country will be affected, but countries with better plans will be less vulnerable to terrorism and other threats during a pandemic Latest Reported Avian Outbreaks: Latest Reported Avian Outbreaks As of May 3, 2006 Cases in Humans: Cases in Humans As of May 3, 2006 World Health OrganizationCumulative Deaths H5N1 as of 8 May 06: World Health Organization Cumulative Deaths H5N1 as of 8 May 06 H5N1 Evolution in Humans : H5N1 Evolution in Humans Genetic changes in virus All human H5N1 isolates from Vietnam and Thailand resistant to adamantane family antiviral drugs Changing epidemiology in Vietnam (Clade 1) Increasing numbers of clusters Expanding age range Decreasing case fatality rate New mutation emerging in Indonesia (Clade 2) H5N1 is the most likely pandemic candidate TODAY Slide20: The World Health Organization Communicable Disease Surveillance & Response (CSR) group reports: Preliminary results on the environmental stability indicate that H5N1 viruses from the 2004 outbreaks have become more stable. H5N1 viruses from 2004 survived at a higher temperature for a longer period of time, compared to the viruses from the 1997 outbreak. Can survive 35 days at low temperature (4 C/ 39 F) Can survive 6 days at higher temperature (37 C/98.6 F) Can survive on surfaces for several weeks Is NOT killed by refrigeration or freezing Viability in the Environment: Intervention Strategies: Anti-Virals: Intervention Strategies: Anti-Virals Moderate symptoms, shorten the recovery 1-2 days and make the infected less contagious Four anti-viral drugs are available for influenza A viruses: amantadine, rimantadine, oseltamivir, and zanamivir You can develop resistance In 2004, isolated H5N1 viruses from poultry and humans in Asia that were resistant to two of the medications (amantadine and rimantadine) in Asia Monitoring of avian viruses for resistance to influenza antiviral medications is ongoing Intervention Strategies for Avian Flu: Vaccines: Intervention Strategies for Avian Flu: Vaccines There are currently no avian influenza vaccines approved in the U.S. for use on humans Vaccine candidate under development (Clade 1) Use as “pre-pandemic” vaccine 4-6 months to produce using current technology after the arrival of the organism How Could H5N1 Get to USA?: How Could H5N1 Get to USA? Genetic separation of H5 AI viruses between New & Old World Asian birds rarely get off course and go to N. America Risk from wild birds is low Migratory Birds - Overlap of summer breeding grounds in Alaska between East Asia/ Australasian and Pacific American flyways Commercial Meat Imports: Commercial Meat Imports 2001 H5N1 isolated from duck meat exported to S. Korea Isolated from meat juice - thawed and refrozen meat Meat from south China AI virus: HP, chickens LP, mice NP, ducks 2003: H5N1 isolated in Japan from imported duck meat from China Risk is low – NO imports from outbreak countries Illegal Commerce: Captive birds Example: 2 eagles from Thailand through Germany to Belgium Possible but great distances reduce chances Illegal Commerce Illegal Commerce: Fighting cocks Entry mechanism from Thailand to Malaysia Possible risk vvNDV in Fresno CA in 2000, Asian Fighting Cocks Illegal Commerce Raw or undercooked products DHS/PPQ – confiscation of products from Asia (pickled eggs, 1000 year eggs) Possible risk but would require feeding of scraps to birds Illegal Commerce: Raw or undercooked products DHS/PPQ – confiscation of products from Asia (pickled eggs, 1000 year eggs) Possible risk but would require feeding of scraps to birds Illegal Commerce International Movement: International Movement Number of Episodes of Illness, Healthcare Utilization, and Death (HHS Plan, 2005): Number of Episodes of Illness, Healthcare Utilization, and Death (HHS Plan, 2005) When a Pandemic First Appears…: When a Pandemic First Appears… There will not be enough vaccine There will not be enough antivirals The health care system will be stretched beyond its limits Many sectors of society will begin to be affected: schools, businesses, large public gatherings, “just-in-time” commerce, air travel, and so on… Source: HHS, William Hall, Director Press Office, 29 July, 2005 Social Disruption May Be Widespread: Social Disruption May Be Widespread Strategies: Social Distancing= 3 feet between people Closing Places of Assembly—Suspend large social gatherings to limit spread “Snow Days” (weeks) and/or Furloughing “non-essential” workers—voluntary closings Restricted movement—border or geopolitical boundaries & quarantine protocols Plan for the possibility that usual services may be disrupted. These could include services provided by hospitals and other health care facilities, banks, stores, restaurants, government offices, and post offices. Prepare backup plans in case public gatherings, such as volunteer meetings and worship services, are canceled Transportation Services May Be Disrupted : Transportation Services May Be Disrupted Strategies: Screen all arriving passengers at ports of entry (n=348) Suspend Public Transportation to Limit Spread Think about how you can rely less on public transportation during a pandemic. For example, store food and other essential supplies so you can make fewer trips to the store. Prepare backup plans for taking care of loved ones who are far away. Consider other ways to get to work, or, if you can, work at home. Schools May Be Closed for an Extended Period of Time : Schools May Be Closed for an Extended Period of Time Strategy: Close schools (snow-days) to limit spread Help schools plan for pandemic influenza. Talk to the school nurse or the health center. Talk to your teachers, administrators, and parent-teacher organizations. Plan home learning activities and exercises. Have materials, such as books, on hand. Also plan recreational activities that your children can do at home. Consider childcare needs. Recap—Avian Influenza: Recap—Avian Influenza Why is Avian Flu dangerous May infect large populations of birds and poultry Has infected humans exposed to diseased birds May mutate to cause human infection At least 4 known subtypes determined in Asia Human to human transmission potential No natural human immunity No current approved vaccine Potential for a pandemic influenza High mortality rate (100% poultry / 80% human) Current antiviral drugs somewhat ineffective US Government Strategy: Focus is on Saving Lives: US Government Strategy: Focus is on Saving Lives Slow spread, decrease illness and death, buy time Antiviral treatment and isolation for people with illness Quarantine for those exposed Social distancing Vaccine when available Local decisions Weeks Impact Prepared Unprepared Criterion Required for a Pandemic: Criterion Required for a Pandemic The Avian H5N1 is widespread and endemic There are continuous outbreaks in poultry It has resulted in lethal mammalian infections Virus is evolving Sporadic human cases Mostly young and healthy Case fatality rate is 50% Rare instances of person-to-person transmission Sustained and rapid person-to-person transmission So…What YOU Can Do-Personally : So…What YOU Can Do-Personally Wash your hands Every opportunity with soap and water Every opportunity with waterless hand cleaner Cover your mouth when you cough or sneeze Keep your environment clean Disinfect surfaces-using household disinfectants Common use items—door handles Personal use items—your phone Teach your kids—they will likely bring it home to you Stay home when you are sick Foodborne Bird Flu: Foodborne Bird Flu Really NOT an issue Wash hands after handling raw poultry and eggs Clean countertops, knives, other utensils, and cutting boards to prevent cross-contamination Follow recommended cooking times and temperatures to kill influenza virus www.pandemicflu.gov: www.pandemicflu.gov Slide40: “Once again, nature has presented us with a daunting challenge: the possibility of an influenza pandemic…Together we will confront this emerging threat and together, as Americans, we will be prepared to protect our families, our communities, this great Nation, and our world” President George W. Bush November 2005 Questions ?????: Questions ?????