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Influenza, or flu, is a respiratory infection caused by several flu viruses.

The Flu Types. Influenza, or flu, is a respiratory infection caused by several flu viruses. Flu viruses are classified as types A, B, and C ; (type A has a number of subtypes). The flu is not the same as the common cold , nor is it related commonly called the “stomach flu.” .

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Influenza, or flu, is a respiratory infection caused by several flu viruses.

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  1. The Flu Types Influenza, or flu, is a respiratory infection caused by several flu viruses. Flu viruses are classified as types A, B, and C; (type A has a number of subtypes). The flu is not the same as the common cold, nor is it related commonly called the “stomach flu.”

  2. Perbandingantipe virus Flu severity of illness animal reservoir human pandemics human epidemics antigenic changes segmented genome amantadine, rimantidine zanamivir surface glycoproteins TYPE A ++++ yes yes yes shift, drift yes sensitive sensitive 2 TYPE B ++ no no yes drift yes no effect sensitive 2 TYPE C + no no no (sporadic) drift yes no effect (1)

  3. Symptoms • Fever* or feeling feverish/chills • Cough • Sore throat • Runny or stuffy nose • Muscle or body aches • Headaches • Fatigue (tiredness) • Some may have vomiting and diarrhea, • (more common in children).

  4. TRANSMISSION • AEROSOL • 100,000 TO 1,000,000 VIRIONS PER DROPLET • 18-72 HR INCUBATION • SHEDDING

  5. PERUBAHAN MUCOSA • DECREASED CLEARANCE • RISK BACTERIAL INFECTION • VIREMIA RARE NORMAL TRACHEA 3 DAYS INFECTION Lycke and Norrby Textbook of Medical Virology 1983

  6. Seasonal Flu the term used to refer to the flu outbreaks that occur yearly, (the late fall and winter). Pandemic Flu virulent strains of flu that spread rapidly create a world-wide epidemic (pandemic). Avian (Bird) Flu the flu virus in wild aquatic birds The virus can pass on the flu to humans. In 1997,a virulent bird influenza had skipped the pig step and had infected humans directly

  7. Flu Complications Most people recover in a few days to less than two weeks, Pneumonia, bronchitis, and sinus and ear infections Chronic health problems worse. asthma may experience asthma attacks chronic congestive heart failure may have worsening People at Higher Risk higher risk of developing serious flu-related complications. 1. 65 years and older, 2. chronic medical conditions (such as asthma, diabetes, or heart disease), pregnant women, and young children.

  8. TYPES OF INTERFERON • TYPE I • Interferon-alpha • (leukocyte interferon, about 20 related proteins) - leukocytes, etc • Interferon-beta • (fibroblast interferon) - fibroblasts, epithelial cells, etc • TYPE II • Interferon-gamma (immune interferon) - certain activated T-cells, NK cells

  9. INDUCTION OF INTERFERON • interferon-alpha and interferon-beta • viral infection (especially RNA viruses), • double stranded RNA, certain bacterial components • strong anti-viral properties • interferon-gamma - antigens, mitogenic stimulation lymphocytes

  10. interferon-alpha, interferon-beta interferon receptor induction of 2’5’oligo A synthase induction of ribonuclease L induction of a protein kinase ds RNA ds RNA 2’5’oligo A activated 2’5’oligo A synthase activated ribonuclease L activated protein kinase ATP ATP phosphorylated initiation factor (eIF-2) 2’5’oligo A mRNA degraded inhibition of protein synthesis

  11. INTERFERON

  12. antiviral state antiviral state antiviral state antiviral state INTERFERON

  13. antiviral state antiviral state antiviral state antiviral state INTERFERON

  14. antiviral state antiviral state antiviral state antiviral state INTERFERON

  15. interferons only made when needed

  16. OTHER EFFECTS OF INTERFERONS ALL TYPES • INCREASE MHC I EXPRESSION • CYTOTOXIC T-CELLS • ACTIVATE NK CELLS • CAN KILL VIRALLY INFECTED CELLS • INTERFERON-GAMMA • INCREASES MHC II EXPRESSION ON APC • HELPER T-CELLS • INCREASES ANTIVIRAL POTENTIAL OF MACROPHAGES • INTRINSIC • EXTRINSIC

  17. THERAPEUTIC USES OF INTERFERONS ANTI-VIRAL e.g. interferon-alpha is currently approved for certain cases of acute and chronic HCV and chronic HBV MACROPHAGE ACTIVATION interferon-gamma e.g. lepromatous leprosy, leishmaniasis, toxoplasmosis ANTI-TUMOR used in e.g. melanoma, Kaposi’s sarcoma, CML MULTIPLE SCLEROSIS interferon-beta

  18. Viral response to host immune system Viruses may : 1.block interferon binding 2.inhibit function of interferon-induced proteins 3.inhibit NK function 4.interfere with MHC I or MHC II expression 5.block complement activation 6.inhibit apoptosis, etc!

  19. SIDE EFFECTS OF INTERFERONS • FEVER • MALAISE • FATIGUE • MUSCLE PAINS

  20. PROTECTION AGAINST RE-INFECTION • IgG and IgA • IgG less efficient but lasts longer • antibodies to both HA and NA important • antibody to HA more important (can neutralize)

  21. PULMONARY COMPLICATIONS • CROUP (YOUNG CHILDREN) • PRIMARY INFLUENZA VIRUS PNEUMONIA • SECONDARY BACTERIAL INFECTION • Streptococcus pneumoniae • Staphlyococcusaureus • Hemophilusinfluenzae

  22. NON-PULMONARY COMPLICATIONS • myositis (rare, > in children, > with type B) • cardiac complications • recent studies report encephalopathy • studies of patients <21 yrs in Michigan - 8 cases seen last season • liver and CNS • Reye syndrome • peripheral nervous system • Guillian-Barré syndrome

  23. Reye’s syndrome • liver - fatty deposits • brain - edema • vomiting, lethargy, coma • risk factors • youth • certain viral infections (influenza, chicken pox) • aspirin

  24. Guillian-Barré syndrome • 1976/77 swine flu vaccine • 35,000,000 doses • 354 cases of GBS • 28 GBS-associated deaths • recent vaccines much lower risk

  25. MORTALITY • MAJOR CAUSES OF INFLUENZA VIRUS- ASSOCIATED DEATH • BACTERIAL PNEUMONIA • CARDIAC FAILURE • 90% OF DEATHS IN THOSE OVER 65 YEARS OF AGE

  26. DIAGNOSIS • ISOLATION • NOSE, THROAT SWAB • TISSUE CULTURE OR EGGS • SEROLOGY • RAPID TESTS • provisional - clinical picture + outbreak

  27. where do “new” HA and NA come from? • 13 types HA • 9 types NA • all circulate in birds • pigs • avian and human

  28. VACCINE • ‘BEST GUESS’ OF MAIN ANTIGENIC TYPES • CURRENTLY • type A - H1N1 • type A - H3N2 • type B • each year choose which variant of each subtype is the best to use for optimal protection

  29. Flu Vaccination types • Two types of vaccines: • I. The “flu shot”— an inactivated vaccine ( killed virus) • use in people older than 6 months, healthy people and • chronic medical conditions.Three different flu shots available: • 1.a regular flu shot (ages 6 months and older) • 2.a high-dose flu shot (people 65 and older), • 3.an intradermal flu shot (people 18 to 64 years) . • II.Thenasal-spray flu vaccine • (LAIV - “Live Attenuated Influenza Vaccine”). • The nasal spray vaccine do not cause the flu. • use in healthy people 2 through 49 years of age not pregnant. • The single best way is vaccinated each year.

  30. FLU VACCINE. who are not at risk for severe illness from influenza should generally not receive vaccine. 1.A flu vaccine is needed every year because flu viruses are constantly changing. 2.The flu vaccine is formulated each year to keep up with the flu viruses as they change. 3.The body’s immunity to influenza viruses ( natural infection or vaccination) declines over time. 4.Getting vaccinated each year provides the best protection against influenza

  31. CONTRA INDICATION FLU VACCINE. 1. a severe allergy to chicken eggs. 2. a severe reaction to an influenza vaccination. 3.Children younger than 6 months of age 4. a moderate-to-severe illness with a fever (they should wait until they recover to get vaccinated.) 5. with a history of Guillain–BarréSyndrome (a severe paralytic illness, also called GBS)

  32. Vaccine Side Effects The flu shotVACCINE The viruses in the flu shot are killed (inactivated), Some minor side effects : Soreness, redness, or swelling where the shot was given Fever (low grade),Aches LAIV (FluMist®) runny nose,headache.sorethroat,cough

  33. RECOMMENDATIONS Persons at High Risk for Influenza-Related Complications · $ 65 years · residents of nursing homes and other chronic-care facilities · adults/children who have chronic pulmonary or cardiovascular disorders, including asthma · adults/children required regular medical follow-up or hospitalization during the last year because of chronic metabolic diseases (including diabetes mellitus), renal dysfunction, hemoglobinopathies, or immunosuppression (including immunosuppression caused by medications) · children and teenagers (6 mths to 18 yrs) receiving long-term aspirin therapy - be at risk for Reye syndrome after influenza · women who will be in the 2nd or 3rd trimester of pregnancy

  34. RECOMMENDATIONS Persons aged 50-64 years increased prevalence of high-risk conditions easier to target by age than by high-risk condition (which may not have been discovered) physicians, nurses, and other personnel hospital and outpatient-care employees of nursing homes and chronic-care facilities who have contact with patients or residents employees of assisted living and other residences for persons in high-risk groups persons who provide home care to persons in high-risk groups household members (including children) of persons in high-risk groups.

  35. RECOMMENDATIONS • others, including travellers and the general population may wish to be vaccinated Children from 0-23 mths are at increased risk for hospitalization from influenza, vaccination is encouraged for their household contacts and out-of-home caretakers, particularly for contacts of children aged 0–5 months because influenza vaccines have not been approved for use among children aged <6 months.

  36. TREATMENT - DRUGS • RIMANTADINE (M2) • type A only, needs to be given early • AMANTADINE (M2) • type A only, needs to be given early • ZANAMIVIR (NA) • types A and B, needs to be given early • OSELTAMIVIR (NA) • types A and B, needs to be given early

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