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Understanding Influenza: Causes, Prevention, and Complications

Learn about the highly contagious infection Influenza, its seasonal occurrences, impact on health, transmission, and complications like pulmonary and nonpulmonary issues. Explore prevention methods and the importance of early diagnosis.

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Understanding Influenza: Causes, Prevention, and Complications

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  1. Influenza (The flu) Presented by: PoorMontaseri Z, DM Infectious Diseases and Tropical Medicine Fasa University of Medical Science

  2. Influenza, commonly known as “the flu”, is a highlycontagious infection of the airways caused by influenza viruses. • In temperate climates, seasonal epidemics occur mainly during winter • In tropical regions, may occur throughout the year, causing outbreaks more irregularly.

  3. در پاندمي آنفلوآنزا (Spanish flu)سال 1918 بيش از 50 ميليون نفر در جهان کشته شده‌اند در پاندمي هاي سالهاي1957 ( Asian flu) و 1968 (Hong kong flu) نيز به ترتيب حدود 2 ميليون نفر و حدود 700/000 نفر در سطح جهان کشته‌ شده‌‌اند

  4. The first cases of human infection with novel H1N1 influenza virus were detected in April 2009 in San Diego and Imperial County, California and in Guadalupe County, Texas. • The virus has spread rapidly.

  5. Distribution of pandemic H1N1

  6. Distribution of Influenza in Iran • Iran reported an increase in influenza detections from previous weeks. • Influenza A(H1N1) viruses were predominant with some A(H3N2) andB detections reported.

  7. The Influenza Virus • RNA viruses/ Subfamily: Orthomyxoviridae. • enveloped viruses that may exist in spherical or filamentous forms of 80 to 120 nm

  8. Antigenic drift? • Minor change • Antigenic shift? • Major change

  9. Point Mutation of Hemagglutinin and Neuraminidase gene Antigenic Drift

  10. Antigenic Shift Human H2N2 Generation of new Human Virus (H3N2) Possessing Hemagglutinin from Avian Virus (H3N8) Human H3N2 Genetic Reassortment Antigenic Shift Avian H3N8

  11. Survival of Influenza viruses in Enviroment • Plastic and steels stuffs: more than 24 h • Cloths and papers: 8-12 h • Viable on hands: <5 minutes only at high viral titers

  12. In virus classification influenza viruses are : • A • Three known A subtypes of influenza viruses currently circulating among humans (H1N1, H1N2, and H3N2). • B • C

  13. Bridges et al. 2008.

  14. Avian Influenza • Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus. • Avian influenza transmitted by birds usually through feces or saliva. • H5N1; the strain of avian flu, • Most cases of avian influenza infection in humans have resulted from contact with infected poultry • The spread of avian influenza viruses from one ill person to another person has been reported very rarely

  15. Swine Flu • Swine influenza (swine flu) is a respiratory disease of pigs caused by typeA influenza virus. • The main swine influenza viruses circulating in U.S. pigs in recent years are: H1N1 influenza virus, H3N2 virus, H1N2 virus. • Disease was more severe among people younger than 65 years of age than in non-pandemic influenza seasons. • With significantly higher pediatric mortality, and higher rates of hospitalizations in children and young adults.

  16. H1N1/H5N1 high morbidity but low mortality rates (1%-4%).

  17. Incubation period The estimated incubation period is unknown and could range from 1-7 days, and more likely 1-4 days.

  18. Transmission and Evolution Influenza virus is transmitted easily from person to person when speaking, by sneezing or coughing and can be confused with other severe Influenza illnesses caused by different viruses. Adults may be contagious from one day prior to the commencement of symptoms to up to 7 days after becoming sick. Children may be contagious for a period of up to 14 days after the appearance of symptoms. Immuno-suppressed more than others.

  19. Relationship between mortality and involvement age • Attack rates are generally highest in the young, (children aged 5--14 years) • whereas mortalityis generally highest among older adults

  20. Complications of Influenza • Pulmonary Complications • primary influenza viral pneumonia and secondarybacterial infection (Streptococcus pneumoniae and Staphylococcus aureus) • Other Pulmonary Complications • Bronchiolitis • Croup • Acute exacerbation of chronic bronchitis • Exacerbations of asthma and worsening pulmonary function in children with cystic fibrosis

  21. Nonpulmonary Complications • Myositis • Cardiac Complications (myocarditis and pericarditis , myocardial infarction) • Toxic Shock Syndrome • Central Nervous Complications (Guillain-Barré syndrome, Reye Syndrome)

  22. Diagnosis • Clinical Diagnosis • Rapid Influenza Diagnostic Tests • Molecular Diagnostic Tests (nucleic acid hybridization and PCR) • Serology (complement fixation and hemagglutination inhibition) • Virus Isolation

  23. Influenza

  24. Type A Influenza Can not be Eradicated • Continous emergence of new virus variant

  25. Prevention: • Primary • Secondary

  26. Prevention in the HealthCare Setting Patients with seasonal influenza can generally be managed under droplet precautions, except when undergoing aerosol-generating procedures, such as bronchoscopy, sputum induction, elective intubation and extubation, and autopsies, during which management requires airborne precautions.

  27. Primary prevention

  28. Vaccination www.fightflu.com

  29. Vaccination/ Common side effects include: • Local reactions at the injection site (soreness, swelling, redness). • Possibly some systemic reactions (fever, headache, muscle or joint aches). these symptoms are mild, self-limited and last 1-2 days. • Guillian-Barre syndrome (1/1000000)

  30. Secondary prevention • Watch for emergency warning • signs • Most people should be able to recover at home, but watch for emergency warning signs that mean you should seek immediate medical care. • In adults: • Difficulty breathing or shortness of breath • Pain or pressure in the chest or abdomen • Sudden dizziness • Confusion • Severe or persistent vomiting • Flu-like symptoms improve but then return with fever and worse cough

  31. Secondary prevention • Emergency warning signs in • children • If a child gets sick and experiences any of these warning • signs, seek emergency medical care. • In children: • Fast breathing or trouble breathing • Bluish or gray skin color • Not drinking enough fluids • Severe or persistent vomiting • Not waking up or not interacting • Irritable, the child does not want to be held • Flu-like symptoms improve but then return with fever and worse

  32. Thanks for your attention

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