Influenza

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Influenza by Nizhny team 2008

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Influenza

  1. 1. Influenza
  2. 2. Influenza <ul><li>The one of the most significant acute upper respiratory tract infections </li></ul><ul><li>A broad array of respiratory illnesses responsible for significant morbidity and mortality in children </li></ul><ul><li>Epidemic disease (influenza virus types A and B) and sporadic disease (type C) in humans </li></ul>
  3. 3. Pandemics <ul><li>the 1918-1919 Spanish pandemic (influenza virus subtype H1N1) </li></ul><ul><li>the 1957 pandemic (subtype H2N2) </li></ul><ul><li>the 1968-1969 pandemic (Hong Kong subtype H3N2) </li></ul><ul><li>and, to a lesser extent, the Russian pandemic in 1977 (subtype H1N1) </li></ul>
  4. 4. <ul><li>the family Orthomyxoviridae </li></ul><ul><li>single-stranded RNA viruses </li></ul><ul><li>3 basic types of virus A, B, C </li></ul><ul><li>structural and biological similarities but vary antigenically </li></ul>
  5. 5. <ul><li>the most significant surface proteins are hemagglutinin and neuraminidase </li></ul><ul><li>The viruses are typed based on these proteins </li></ul><ul><li>For example, influenza A subtype H3N2 expresses hemagglutinin 3 and neuraminidase 2 </li></ul>
  6. 6. <ul><li>The most common prevailing human influenza A subtypes are H1N1 and H3N2 </li></ul><ul><li>The trivalent vaccine contains A strains from H1N1 and H3N2, along with an influenza B strain </li></ul>
  7. 7. <ul><li>Influenza A is generally more pathogenic than influenza B </li></ul><ul><li>Influenza A is a zoonotic infection, and more than 100 types of influenza A infect most species of birds, pigs, horses, dogs and seals </li></ul>
  8. 8. H5N1 bird flu <ul><li>In 1997, an avian subtype,H5N1, was first described in Hong Kong </li></ul><ul><li>The H5N1 flu is transmitted to humans from birds </li></ul><ul><li>more than 240 human cases have been documented and more than 140 persons have died </li></ul>
  9. 9. <ul><li>Experts are concerned that a slight mutation could convert H5N1 to a strain that would be easily transferred from human to human </li></ul><ul><li>Such a strain could potentially spread rapidly and precipitate a catastrophic worldwide pandemic </li></ul>
  10. 10. Pathophysiology <ul><li>Respiratory transmission </li></ul><ul><li>The virus attaches to and penetrates respiratory epithelial cells in the trachea and bronchi </li></ul><ul><li>Viral replication occurs, which results in the destruction of the host cell </li></ul><ul><li>Viremia does not occur </li></ul><ul><li>The virus is shed in respiratory secretions for 5-10 days </li></ul>
  11. 11. Epidemiology <ul><li>Highly contagious </li></ul><ul><li>Is spread when an individual inhales infected air-borne droplets or comes in direct contact with an infected person's secretions </li></ul><ul><li>In the winter and spring </li></ul><ul><li>Typical symptoms begin 2-3 days after exposure to the virus </li></ul>
  12. 12. Clinical manifestations <ul><li>Abrupt onset of illness </li></ul><ul><li>Fever 39 – 40 C, chills </li></ul><ul><li>Severe headache </li></ul><ul><li>Weakness, severe fatigue </li></ul><ul><li>Myalgias </li></ul><ul><li>Ocular symptoms (photophobia, burning sensations, pain upon motion) </li></ul><ul><li>Sore throat (pharyngitis) </li></ul><ul><li>Tachycardia resulting from hypoxia, fever </li></ul>
  13. 13. Subsequent catharal and respiratory symptoms <ul><ul><li>Nasal congestion </li></ul></ul><ul><ul><li>Rhinitis </li></ul></ul><ul><ul><li>Nonproductive cough </li></ul></ul><ul><ul><li>Cough-related pleuritic chest pain </li></ul></ul><ul><ul><li>Dyspnea </li></ul></ul><ul><ul><li>Wheezing, rhonchi </li></ul></ul><ul><ul><li>Cervical lymphadenopathy </li></ul></ul>
  14. 14. Influenza in infants <ul><li>Conjunctivitis, rhinitis, and gastrointestinal tract symptoms are reported more commonly </li></ul><ul><li>In young infants, influenza may produce a sepsislike picture with shock </li></ul><ul><li>Occasionally, influenza viruses can cause croup or pneumonia </li></ul>
  15. 15. Complications <ul><li>Primary influenza viral pneumonia </li></ul><ul><li>Secondary bacterial pneumonia </li></ul><ul><li>Croup </li></ul><ul><li>Myositis </li></ul><ul><li>Myocarditis </li></ul><ul><li>Toxic shock syndrome </li></ul><ul><li>Reye syndrome </li></ul>
  16. 16. Reye syndrome <ul><li>Acute noninflammatory encephalopathy and hepatic failure </li></ul><ul><li>The etiology of Reye syndrome is unknown </li></ul><ul><li>Occurs after a viral illness (upper respiratory tract infection, influenza, varicella, or gastroenteritis), and the use of aspirin during the illness </li></ul><ul><li>Decrease in the use of aspirin among children have made the diagnosis and occurrence of Reye syndrome rare </li></ul>
  17. 17. Lab Studies <ul><li>Findings of standard laboratory studies are nonspecific </li></ul><ul><li>Viral culture of nasal-pharyngeal samples, throat samples, or both </li></ul><ul><li>Direct immunofluorescent tests </li></ul><ul><li>Serologic studies </li></ul><ul><li>Chest radiography - to exclude pneumonia </li></ul>
  18. 18. Treatment <ul><li>Etiological : </li></ul><ul><li>Antiviral drugs </li></ul><ul><li>α - Interferons </li></ul><ul><li>Interferon's inductors </li></ul><ul><li>Symptomatic – detoxication </li></ul><ul><li>- antipyretics (paracetamol 10-15 mg/kg) </li></ul><ul><li>- antihistamins (clemastin, loratadin) </li></ul><ul><li>- mucolythics (ambroxol) </li></ul><ul><li>- anticongestants (oxymetazolin) </li></ul>
  19. 19. Antiviral medications <ul><li>Influenza antiviral medications should be started as soon as possible after symptom onset </li></ul><ul><li>These medications have not been shown to be effective if administered more than 48 hours after onset </li></ul><ul><li>They can reduce illness severity and shorten duration of illness </li></ul><ul><li>They may also prevent serious influenza-related complications (e.g., pneumonia or exacerbation of chronic diseases) </li></ul>
  20. 20. Antiviral Drugs RNA mutagen Broad spectrum Ribavirin Neuraminidase Inhibitor Influenza strains A and B Oseltamivir and Zanamivir Matrix protein / haemagglutinin Influenza A strains Amantadine / Rimantadine Target Virus Drug
  21. 21. Antiviral Drugs <ul><li>Amantadine </li></ul><ul><li>4,5-5 mg/kg, not > 150 mg/day </li></ul><ul><li>Rimantadine </li></ul><ul><li>7-10 years - 50*2 times/day </li></ul><ul><li>11-14 years - 50*3 times/day </li></ul><ul><li>Ribavirin </li></ul><ul><li>10 mg/kg/day </li></ul><ul><li>(RSV-infection – 20mg/ml/12 hours inhalations) </li></ul>
  22. 22. Oseltamivir <ul><li>Oseltamivir is approved for treatment among persons aged 1 year and older and for chemoprophylaxis among persons aged 13 years and older. </li></ul><ul><li>Recommended treatment dosages for children vary by the weight of the child: </li></ul><ul><li>15 kg or less - is 30 mg twice a day </li></ul><ul><li>>15-23 kg the dosage is 45 mg twice a day; </li></ul><ul><li>>23-40 kg the dosage is 60 mg twice a day; </li></ul><ul><li>>40 kg the dosage is 75 mg twice a day. </li></ul><ul><li>Dosages for chemoprophylaxis are the same for each weight group, but doses are administered only once per day. </li></ul>
  23. 23. Zanamivir <ul><li>Zanamivir is approved for treatment among children aged 7 years and older </li></ul><ul><li>The recommended dosage of zanamivir for treatment of influenza is two inhalations (one 5-mg blister per inhalation for a total dose of 10 mg) twice daily (approximately 12 hours apart) </li></ul><ul><li>Zanamivir is approved for chemoprophylaxis of influenza among children aged 5 years and older - the dosage is 10 mg (2 inhalations) once a day </li></ul>
  24. 24. Chemoprophylaxis <ul><li>Vaccination is the best way to prevent influenza - safe and effective immunity throughout the influenza season </li></ul><ul><li>Antiviral medications are useful adjuncts to vaccination </li></ul><ul><li>To be effective as prophylaxis, the drug must be taken each day for the duration of potential exposure to influenza or until immunity after vaccination develops </li></ul>
  25. 25. <ul><li>WHO determines influenza vaccine contents annually </li></ul><ul><li>Typically, 3 live attenuated virus strains, which antigenically represent the influenza strains likely to circulate the next flu season, are included in the formulation each year </li></ul>
  26. 26. <ul><li>For the 2006-2007 season, the trivalent vaccine contained the following antigenic strains: </li></ul><ul><li>influenza A - H1N1: New Caledonia/20/1999 </li></ul><ul><li>influenza A - H3N2: Wisconcin/67/2005 or equivalent; </li></ul><ul><li>and influenza B: Malaysia 2506/2004 or equivalent </li></ul>
  27. 27. Vaccination is recommended <ul><ul><li>Persons older than 65 years </li></ul></ul><ul><ul><li>Patients with chronic pulmonary, cardiac, metabolic , renal disease, immunosuppression </li></ul></ul><ul><ul><li>Children and teenagers with long-term use of aspirin </li></ul></ul><ul><ul><li>Pregnant women in their second or third trimester during influenza season </li></ul></ul><ul><ul><li>Physicians, nurses, and other health care providers </li></ul></ul><ul><ul><li>Employees and residennts of nursing homes </li></ul></ul><ul><ul><li>Household members of persons at high risk </li></ul></ul><ul><ul><li>Providers of essential community services (police, fire) </li></ul></ul><ul><ul><li>Students and dormitory residents </li></ul></ul><ul><ul><li>Anyone wishing to reduce risk of influenza </li></ul></ul>
  28. 28. Vaccination <ul><li>Influvac (Netherlands) </li></ul><ul><li>Fluarix (England) </li></ul><ul><li>Agrippal S1 (Germany) </li></ul><ul><li>Begrivac (Germany) </li></ul><ul><li>Vaxigrip (France) </li></ul><ul><li>Grippol (Russia) </li></ul>
  29. 29. Child with croup. Note the steeple or pencil sign of the proximal trachea evident on this anteroposterior film.

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