Uploaded byDeepak Upadhyay
Influenza
The document discusses influenza, also known as seasonal flu. It is an acute respiratory infection caused by influenza viruses that causes symptoms like fever, cough, and muscle pain. Influenza occurs seasonally as well as sporadically, and can sometimes cause pandemics every 10-40 years when the virus undergoes major antigenic changes. Influenza viruses are classified into types A, B, and C. Type A is responsible for epidemics and pandemics. The document outlines the epidemiology, transmission, clinical features, diagnosis, treatment and prevention of influenza. Vaccination is recommended for high-risk groups to reduce complications.
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Influenza
- 1. INFLUENZA Dr. Deepak Upadhyay Departmentof Community Medicine
- 2. Also know as‘’SEASONAL FLU’’ Influenza is an ‘acute Respiratory tract infection’ caused by influenza virus characterized by sudden onset of chills, malaise, fever, muscular pain and cough. Can occur as Sporadic case / seasonal case Epidemic case Pandemic case
- 3. PROBLEM STATEMENT • Itsan international disease • Occur in all countries and affect millions of people • May occur pandemic every 10-40 years due to major antigenic changes as occurred in -1918 - SPANISH INFLUENZA -1957 - ASIAN INFLUENZA -1968 - HONG KONG INFLUENZA -2009 – H1N1 FLU
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- 6. AGENT FACTOR • Influenzavirus, classified under ‘’Orthomyxovirs’’ • RNA virus • Three sub types • Type A • Type B • Type C • Influenza A virus have 2 distinct surface antigen • Heamagglutinin (H) – Attachment of virus to susceptible cell • Neuraminidase (N) - Release of virus from infected cell
- 8. Type A TypeB Type C Causes Significant Disease Causes Significant Disease Only in apparent cases Epidemic & Pandemic Milder Epidemic High Morbidity & Mortality Less Morbidity & Mortality Infect Human & other species Only human Only human Antigenic variations frequently Antigenic variations infrequent Antigenic variations infrequent
- 9. What is antigenicshift and drift • Antigenic shift results from genetic recombination of human and animal or avian virus • Antigenic Drift involve point mutation in the gene • Type B show lessor degree changes and Type C is antigenically stable
- 10. RESERVOIR OF INFECTION • Majorreservoir of human seasonal influenza are animals and birds • Human cases & subclinical cases – primary reservoir • Virus isolate from many animals and birds like swine, horses , dogs, domestic poultry, and wild birds etc. • New stains form due to recombination between man, animals and birds. • Migratory waterfowls (wild duck) are natural reservoir for Avian influenza
- 11. SOURCE OF INFECTION •Cases or subclinical cases – Human seasonal influenza • During epidemic asymptomatic infection occur, play important role in spread of infection • Respiratory tract secretions are also infective • Birds, poultry material infected with bird excreta/secretions & birds meat – Avian Flu
- 12. Period of infectivity •Human Seasonal influenza • 3-5 days from clinical onset – Adults • 7 days from clinical onset – Children • Highest infectivity – during 1st day • Avian influenza – cases are not infective
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- 14. AGE and SEX •All age groups and both sexes are affected • Attack rate is lower among adults • Children constitute an important link in transmission chain
- 15. Mortality rate • Highestmortality rate during epidemic among • Old People (generally over 85) • Children under 18 months • Person with systemic diseases such as: - chronic heart disease CHD - respiratory diseases - renal disease - diabetics person
- 16. IMMUNITY • Appear –7 days • Drops to pre infection level – 12 months • Specific antibodies against HA and NA • Resistance to initiation of infection is related to antibody against HA • Decrease severity of disease and decrease transmission related to NA
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- 18. • SEASON • Epidemicusually occur in winter month in Temperate zone • In Tropical zone outbreaks occur in rainy season • OVERCROWDING - Enhance transmission
- 19. MODE OF TRANSMISSION Human seasonal influenza Person to person Droplet infection or droplet nuclei Use of fomites Portal of Entry - respiratory tract Avian influenza Birds to human Feco-oral route (excreta of poultry) Direct contact Ingestion of under cooked food
- 20. INCUBATION PERIOD • Humanseasonal influenza 1 to 4 days • Avian influenza 2 to 5 days
- 21. PATHOGENSIS Virus Superficial Epithelium ofrespiratory tract Inflammation Necrosis
- 22. CLINICAL FEATURES Human seasonalinfluenza • Fever High grade • Chills • Significant Generalized ache and pain • Headache, myalgia • Coughing • Generalized weakness and exhaustion Fever last for 1-5 days and average 3 days in adults
- 23. Features Influenza Commoncold Fever High Uncommon Headache Present Uncommon Fatigue/Weakness Moderate Mild Pain, aches Moderate Mild Exhaustion Severe Absent Stuffy nose & Sore throat Uncommon Common Cough Present Uncommon
- 24. CLINICAL FEATURES Avian influenza •Fever high grade • Generalized ache and pain • Headache and myalgia • Coughing (severe) • Diarrhea • Generalized weakness • Signs of lower respiratory tract infection
- 25. CLINICAL FEATURES Pandemic influenza(H1N1 influenza) Uncomplicated influenza • Fever • Cough, running nose • Sore throat • Muscle pain • Malaise • No dyspnea and shortness of breath • GIT symptom may also present Complicated influenza • Shortness of breath and dyspnea • Lower RTI(pneumonia) • CNS involvement • Sever dehydration • Secondary complications • COPD asthma renal failure
- 26. Specimens / samples Human seasonal influenza & Pandemic influenza Nasal/nasopharyngeal swab Oropharyngeal swab Throat swab – not useful after 2 days of illness Avian influenza Endotracheal swab Nasal/nasopharyngeal swab Oropharyngeal swab Throat swab Transportation of sample – Triple packing system
- 27. LAB DIAGNOSIS • VIRUSISOLATION – • Viral culture in egg culture (Gold Standard) • Viral RNA can be detected by • RT-PCR (best method for initial diagnosis) • SERIOLOGY – antibodies detection by Heamagglutination inhibition (HI) ELISA 4 folds increase in titer between acute & convalescent phase indicate the influenza infection
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- 29. Symptomatic management Coughsuppression Decongestants Paracetamol for fever (Salicylates must be avoided) Antiviral drugs M2 inhibitors –Amantadine, Rimantadine Neuraminidase inhibitors – Oseltamivir, Zanamivir Influenza A is treated with zanamivir or combination of oseltamivir and rimantadine Influenza B is treated with osaltamivir Supportive management Oxygen therapy, Antibiotics, steroids etc.
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- 31. General Measures • Goodventilation of public buildings • Avoid overcrowding specially during epidemics • Cover your mouth while sneezing and coughing • Immunization vaccine must administrate at least 2 weeks before the onset of epidemic • Hand hygiene • Personal protective equipment • Persons of high risk of transmission
- 32. VACCINE FOR SELECTED POPULATION •In industries to reduce absenteeism • In public servants to prevent critical public services • Certain age groups like elders and children under 18 month to prevent from sever complications • Also the people with chronic illness like systemic diseased to prevent death • Peoples travelling to epidemic/outbreak area
- 34. Killed vaccine (ForHuman seasonal influenza) • Required strains of vaccine are grown in allantonic cavity of chick embryo • Harvested purified and killed by beta- propiolacton • Formulation: Aqueous or Oil adjuvant • Dose: (1/2 dose for Oil adjuvant) • 0.5 ml for adults and children over 3 years • 0.25 ml for children from 6 to 3 years
- 35. • Primary Doses– 2 doses 1 month apart • Route - Subcutaneous • Site of injection - Deltoid region • Immunity duration • Aqueous vaccine – 6 months • Oil adjuvant vaccine – 1 year • Revaccination – every year
- 36. Live Attanuated Vaccine (ForHuman seasonal influenza) • Live attenuated • Freeze dried • Diluent – Distilled water • Single dose • Intranasal spray • Revaccination every year
- 37. CONTRAINDICATION OF VACCINE • Peoplewith h/o anaphylactic shock • People with h/o sever reaction to influenza vaccine • Who develop Guillain-Barre syndrome • Children less then 6 month of age (inactivated influenza vaccine is not approved) • People with moderate to sever fever
- 38. Killed vaccine (ForH1N1 Influenza) • Split virion, Inactivated vaccine • Route – Intramuscular • Site of injection – Anterolateral Thigh or Deltoid region • Dose: (1/2 dose for Oil adjuvant) • 0.5 ml for adults and children over 3 years • 0.25 ml for children from 6 to 3 years Schedule : 6 months to 9 years – 2 doses one month apart > 9 years – 1 dose
- 39. Live Attanuated Vaccine (ForH1N1 influenza) • Live attenuated • Freeze dried • Age – Children above 3 years • Diluent – Distilled water • Single dose • Intranasal spray • Revaccination every year
- 40. THANK YOU FORYOUR ATTENTION!