Influenza
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Influenza

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Influenza Influenza Presentation Transcript

  • Saturday, May 29, 2010
  • INFLUENZA Jaime A. Santos Saturday, May 29, 2010
  • Influenza • commonly called “the flu” • a contagious respiratory illness caused by influenza viruses • Infection with influenza viruses can result in illness ranging from mild to severe with life- threatening complications Saturday, May 29, 2010
  • Saturday, May 29, 2010
  • 1918 Spanish flu pandemic: 20 to 50 million people may have died worldwide Saturday, May 29, 2010
  • Saturday, May 29, 2010
  • Viral Titers Peak Early Saturday, May 29, 2010
  • “Flu” symptoms Fever/ chills Headache Nasal congestion Sore throat Dry cough Myalgia/ body aches GI symptoms Malaise/ tiredness Saturday, May 29, 2010
  • Influenza - Clinical Signs and Symptoms • incubation period for influenza is 1--4 days, with an average of 2 days • Adults - infectious from the day before symptoms begin through approximately 5 days after onset • Children - infectious for > 10 days, and young children can shed virus for < 6 days before their illness onset • immunocompromised persons can shed virus for weeks or months Saturday, May 29, 2010
  • Influenza - Clinical Signs and Symptoms • resolves after a limited number of days for the majority of persons, although cough and malaise can persist for >2 weeks • young children can have initial symptoms mimicking bacterial sepsis with high fevers – < 20% of children hospitalized with influenza can have febrile seizures Saturday, May 29, 2010
  • Influenza - Clinical Signs and Symptoms • Influenza infection has also been associated with encephalopathy transverse myelitis Reye syndrome myositis myocarditis pericarditis Saturday, May 29, 2010
  • Influenza - Hospitalization and Deaths • Population at risk for complications, hospitalizations, & deaths:> 65 years old – young children – persons of any age with certain underlying health conditions: cardiovascular and pulmonary (including asthma), metabolic e.g. DM, Hgbpathies, immunosuppression – receiving long term ASA Saturday, May 29, 2010
  • “U” Shaped Epidemic Curve of Influenza During the Interpandemic Period Visits/100 ARD Hospitalizations/10,000 P&I Mortality/100,000 Rate Age group Saturday, May 29, 2010
  • “U” Shaped Epidemic Curve of Influenza During the Interpandemic Period 120 Visits/100 ARD Hospitalizations/10,000 P&I Mortality/100,000 100 80 Rate 60 40 20 0 <5 5–9 10–14 15-19 20-24 25-34 35-44 45-54 55-64 > 64 Age group Saturday, May 29, 2010
  • “U” Shaped Epidemic Curve of Influenza During the Interpandemic Period 120 Visits/100 ARD Hospitalizations/10,000 P&I Mortality/100,000 100 80 Rate 60 40 20 0 <5 5–9 10–14 15-19 20-24 25-34 35-44 45-54 55-64 > 64 Age group Saturday, May 29, 2010
  • “U” Shaped Epidemic Curve of Influenza During the Interpandemic Period 120 Visits/100 ARD Hospitalizations/10,000 P&I Mortality/100,000 100 80 Rate 60 40 20 0 <5 5–9 10–14 15-19 20-24 25-34 35-44 45-54 55-64 > 64 Age group Saturday, May 29, 2010
  • “U” Shaped Epidemic Curve of Influenza During the Interpandemic Period 120 Visits/100 ARD Hospitalizations/10,000 P&I Mortality/100,000 100 80 Rate 60 40 20 0 <5 5–9 10–14 15-19 20-24 25-34 35-44 45-54 55-64 > 64 Age group Saturday, May 29, 2010
  • Influenza Responsible for Substantial Disease Deaths 36,0001 Hospitalizations 114,0002 Physician visits 25 million3 Infections and illnesses 50–60 million3 Direct medical costs $1-$3 billion4 1. Thompson WW et al. JAMA. 2003;289:179-186. 2. CDC. MMWR Recomm Rep. 2003;58(RR-8):1-34. 3. Couch RB. Ann Intern Med. 2000;133:992-998. 4. Patriarca PA. JAMA. 1999;282:75-77. Saturday, May 29, 2010
  • Seasonal • In colder countries flu is largely seen during colder months and they vaccinate prior to this season (e.g. October) • In tropical countries flu is seen all year round Saturday, May 29, 2010
  • Flu Season in the Philippines Southern Hemisphere Pattern Cumulative Data: RITM Influenza Surveillance Data Feb. 1998 – Oct. 2004 B A Saturday, May 29, 2010
  • Flu Season in the Philippines Southern Hemisphere Pattern Cumulative Data: RITM Influenza Surveillance Data Feb. 1998 – Oct. 2004 80 70 60 50 B A 40 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Saturday, May 29, 2010
  • Influenza virus types • Three : Influenza A, B, and C • Influenza types A or B viruses cause epidemics; influenza A may cause pandemics • Getting a flu shot can prevent illness from types A and B influenza but not from type C • Influenza type C causes mild respiratory illness ; not thought to cause epidemics Saturday, May 29, 2010
  • Influenza Virus: Segmented genome Saturday, May 29, 2010
  • Influenza A virus divided into subtypes based on HA and N proteins on surface • 15 HA, 9 N • Nomenclature based on: site of origin isolate number year of isolation subtype Example: influenzaA/ Johannesburg/33/94 (H3N2) Saturday, May 29, 2010
  • Drift or shift • “Antigenic drift" - small changes in the virus that happen continually (influenza A and B) • “Antigenic shift” - abrupt, major change in the influenza A viruses, resulting in new H &/or new H and N proteins that infect humans (influenza A only) Saturday, May 29, 2010
  • Influenza subtypes in humans • current subtypes of influenza A viruses found in people are A(H1N1) and A(H3N2) • Influenza B virus is not divided into subtypes • Influenza A(H1N1), A(H3N2), and influenza B strains are included in each year's influenza vaccine • Protection is serotype specific Saturday, May 29, 2010
  • Saturday, May 29, 2010
  • Domestic pig: Domestic poultry Mixing vessel Migratory water birds Saturday, May 29, 2010
  • Domestic pig: Domestic poultry Mixing vessel Migratory water birds Saturday, May 29, 2010
  • Avian Influenza • Caused by 15 subtypes of influenza A virus subtype of avian influenza • Low pathogenicity avian influenza (LPAI) • Highly pathogenic avian influenza (HPAI) – First recognized in Italy in 1878 – Extremely contagious in birds – Rapidly fatal, high mortality (almost 100% in a few days) Saturday, May 29, 2010
  • Avian Influenza Infections in Humans Confirmed instances of avian influenza viruses infecting humans since 1997 • 1997: Hong Kong, avian influenza A (H5N1) • 1999: Hong Kong, avian influenza A(H9N2) • 2003: 2 cases of avian influenza A (H5N1) • 2003:H9N2 infection was confirmed in a child in Hong Kong • 2003: Avian influenza A (H7N7) infections among poultry workers / families in the Netherlands (> 80 cases ) Saturday, May 29, 2010
  • Characteristics of Avian Influenza Infections in Humans • reported symptoms of avian influenza : typical influenza-like symptoms (e.g., fever, cough, sore throat and muscle aches) to eye infections, pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications • It is believed that most cases of H5N1 infection in humans have resulted from contact with infected poultry or contaminated surfaces CDC Saturday, May 29, 2010
  • Current Avian Flu (H5N1) Strain – genetically sequenced: all bird origin – antiviral resistance to amantadine and rimantadine – oseltamavir and zanamivir should still be effective Saturday, May 29, 2010
  • Avian Influenza (Bird Flu) Outbreak Why H5N1 is of particular concern • H5N1 mutates and acquires genes rapidly from other species • Documented to cause severe disease in humans • avian influenza virus could change so that it could infect humans and could spread easily from person to person • no immune protection against them in the human population • If an avian virus were able to infect people and gain the ability to spread easily from person to person, an “influenza pandemic” could begin Saturday, May 29, 2010
  • FLU PANDEMICS: THEN AND NOW 1918 Year 2005 WHAT HAPPENED WHAT COULD HAPPEN 1.8 billion World Population 7 billion Troop ships, Primary mode of transportation Jets railroad Time for virus to circle 4 months the globe 4 days Gauze masks, Preventive measures Vaccines disinfectants Bed rest, Treatments Some antiviral drugs aspirin 20+ million Estimated dead 60 million? Janet Englund, MD PIDSP Feb. 2005 Saturday, May 29, 2010
  • Treatment of Influenza • Antiviral Medications: – antiviral drugs: adamantanes: amantadine, rimantadine neuraminidase inhibitors: zanamivir, oseltamivir – Antiviral treatment lasts for 3-5 days and must be started within the first 2 days of illness. Saturday, May 29, 2010
  • Antiviral treatment and prophylaxis • amantadine [4.4-8.8 mg/kg/day, not to exceed 150 mg/day] can be given for 3-5 days; for treatment of influenza A • oseltamivir [2 mg/kg/dose BID] can be given for 5 days for treatment of influenza A and B. Its use for treatment and prophylaxis of household contacts has been effective for children > 12 years old Saturday, May 29, 2010
  • Saturday, May 29, 2010
  • Do I Need A Flu Shot? Saturday, May 29, 2010
  • Target Groups For Vaccination 1. Those with increased risk of complications: • Persons age 50 yrs old and above • Children from 6 to 23 months old • Adults and children with the following risk factors: – Chronic cardiovascular disease (e.g. congestive heart failure, Hypertensive cardiovascular disease, valvular heart disease, rheumatic heart disease, stroke) – Chronic lung disease (e.g COPD, asthma, bronchiectasis, malignancies, chronic PTB) Saturday, May 29, 2010
  • • Chronic metabolic disease (diabetes mellitus) • Chronic renal dysfunction • Hemoglobinopathies • Immunosuppressed (e.g.HIV, malignancies, immunosuppressive drugs, radiation therapy, transplant patients) • Children and adolescents who are receiving long- term aspirin therapy • Residents of nursing homes and other chronic care facilities • Pregnant women on their 2nd or 3rd trimester who have not received their flu vaccine within the last 12 months. Saturday, May 29, 2010
  • Target Groups For Vaccination 2. Those who can transmit the disease to others • Health care workers and other personnel of out patient care settings, hospitals, nursing homes, and chronic care facilities. • Household contacts (including children) and caregivers of person at high risk. Saturday, May 29, 2010
  • When Should You Give the Flu Shot? Highlights Influenza Consensus – Flu TWG Oct. 2004 • Data from the five-year epidemiologic data (February 1998 – September 2003) shows increased influenza activity June to November. • Vaccination should be given once a year preferrably from February to June • The Southern Hemisphere vaccine which is made available starting February of each year is recommended to cover the expected increase in influenza activity from June to November. Saturday, May 29, 2010
  • Vaccine dosage by age group Age Dose No. doses Route 6 – 35 mos 0.25 ml 1 or 2* IM 3 – 8 yrs 0.5 ml 1 or 2* IM = or > 9 0.5 ml 1 IM yrs * 2 if receiving vaccine for 1st time, 1 month apart Saturday, May 29, 2010
  • 38 Saturday, May 29, 2010
  • Thank You! 38 Saturday, May 29, 2010