INFLUENZA

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this is just a basic concept of influenza foe medical students.

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INFLUENZA:

Presented by, Dr. Rachel. Sushmita. Daniel INFLUENZA

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INTRODUCTION Influenza , commonly referred to as the flu , is an infectious disease caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses), that affects birds and mammals. The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness/fatigue and general discomfort . Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease than the common cold and is caused by a different type of virus.

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EPIDEMIOLOGY Influenza can be traced as far back as 400 BC In Hippocrates’ Of the Epidemics, he describes a cough outbreak that occurred in 412 BC in modern-day Turkey at the turn of the autumn season 18 th century:- Between 1781-1782, an influenza epidemic infected 2/3 of Rome’s population and ¾ of Britain’s population Disease spread to North America, West Indies, and South America Spread of pandemic culminated in New England, New York, and Nova Scotia in 1789 1781 marked the beginning of the 10-40 year cycle of influenza epidemics and pandemics

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19 th century Asia 1829 Spread to Indonesia by January 1831 Russia 1830 Spread throughout Russian and westward between 1830 and 1831 By November 1831, the influenza outbreak reached America Epidemics prevalent until 1851

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20 th century Name of pandemic Date Deaths Asiatic Flu 1889-1890 1 million Spanish Flu 1918-1920 40 -100 million Asian Flu 1957-1958 1 - 1.5 million Hong Kong Flu 1968-1969 0.75 - 1 million

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American Red Cross nurses tend to flu patients in temporary wards set up inside the Oakland municipal Auditorium.

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Avian flu Use of face masks during pandemic.

Structure of Virion:

Structure of Virion M1 protein helical nucleocapsid (RNA plus NP protein) HA - hemagglutinin polymerase complex lipid bilayer membrane NA - neuraminidase 100 n m Influenza virions are SMALL. The average eukaryotic cell diameter is 10,000 nm (10 microns), which is 100 times bigger than the influenza virion diameter.

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INFLUENZA SUBTYPES Types A & B 3 IMPs HA NA M2 8 Segments of RNA Responsible for epidemics & pandemics Type C 1 IMP HEF Serves functions of both HA and NA 7 Segments of RNA Causes only mild infections Influenza strains are subtyped A, B, or C based on the relatedness of the matrix (M1) and nucleoprotein (NP) antigens All 3 subtypes can infect human, subtype A can also infect other mammals and birds Within each subtype, there are many variant strains

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1) HA binds a cell GP at a Sialic Acid Binding Site 2) Clathrin-Coated pit endocytoses virion Low pH PATHOGENESIS

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1) HA binds a cell GP at a Sialic Acid Binding Site PATHOGENESIS

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1) HA binds a cell GP at a Sialic Acid Binding Site 2) Clathrin-Coated pit endocytoses virion 3) Conformational Change: Hydrophobic binding of HA to vesicle membrane Low pH PATHOGENESIS

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1) HA binds a cell GP at a Sialic Acid Binding Site 2) Clathrin-Coated pit endocytoses virion 3) Conformational Change: Hydrophobic binding of HA to vesicle membrane Low pH PATHOGENESIS 4) RNPs are released into cytoplasm for replication and transcription (vRNA and mRNA)

MODE OF TRANSMISSION:

MODE OF TRANSMISSION AEROSOL 100,000 TO 1,000,000 VIRIONS PER DROPLET The virus is spread by inhalation or by direct contact. Reservoirs of infection are primarily humans, but birds and pigs can act as reservoirs.

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SIGNS AND SYMPTOMS Symptoms begin 1-4 days after infection. You can spread the flu before your symptoms start and 3-4 days after your symptoms appear. The following symptoms of the flu can vary depending on the type of virus, a person’s age and overall health: Sudden onset of chills and fever (101 – 103 degrees F) Sore throat, dry cough Fatigue, malaise Terrible muscle aches, headaches Diarrhea Dizziness

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DIFFERENCE BETWEEN COLD AND FLU Symptoms Cold Flu Fever Rare High Headaches rare prominent General aches mild severe Fatigue mild Can last for 2-3 weeks Extreme exhaustion absent Early and prominent Blocked nose common sometimes sneezing Usual sometimes Sore throat common sometimes Chest discomfort Mild present

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DIAGNOSIS Individuals with symptoms of influenza should see their doctor for a thorough physical exam. Rapid influenza tests, viral cultures, and serum samples can be used to confirm infection by the influenza virus since the symptoms of the flu are similar to the symptoms caused by other infections.

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RAPID INFLUENZA TESTS These tests are 70% accurate for determining if the patient has been infected with the influenza virus and 90% accurate for determining the type of influenza pathogen. Examples of rapid influenza tests: Directigen Flu A, Directigen Flu A + B, Flu OIA, Quick Vue, and Zstat flu. Rapid influenza tests provide results in 24 hours and can be performed in the physician’s office.

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VIRAL CULTURE Samples to be tested by viral cultures need to be collected from the first four days of infection. The viral culture can be performed from nasopharyngeal or throat swabs, nasal wash, or nasal aspirates. The results are made available within 3 to 10 days.

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SERUM SAMPLES Blood samples can be tested for the presence of influenza antibody to diagnose recent infection. Two samples should be collected: one sample within the first week of illness and a second sample 2-4 weeks later. If antibody levels increase from the first to the second sample, influenza infection likely occurred.

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TREATMENT Increase liquid intake like water, juice, and soups. Get plenty of rest for the 7 to 10 days during which the symptoms may persist. Take anti-fever drugs to relieve the fever. Anti-viral drugs have recently been designed to treat the flu. If patients begin taking these drugs within 48 hours after their symptoms begin, the drugs may reduce the length of the illness by about 1 to 2 days.

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ANTI-VIRAL DRUGS All anti-viral drugs inhibit viral replication but they act in different ways to achieve this. Drugs that are effective against influenza A viruses: amantadine and rimantadine. Drugs that are effective against influenza A viruses and influenza B viruses: zanamivir and oseltamivir. Amantadine Rimantadine Zanamivir Oseltamivir Type of Influenza virus infection indicated for use Influenza A Influenza A Influenza A Influenza B Influenza A Influenza B Administration oral oral oral inhalation oral Ages approved for treatment of flu 1 year 14 year 7 years 18 years Ages approved for prevention of flu 1 year 1 year not approved not approved

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SYMPTOMATIC DRUGS OTC medicines provide relief for 'flu symptoms Symptom(s) OTC Medicine fever , ache, pains , sinus pressure, sore throat analgesics nasal congestion , sinus pressure decongestants sinus pressure, runny nose , watery eyes , cough antihistamines cough cough suppressant sore throat local anaesthetics

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COMPLICATIONS A bacterial “superinfection” can develop when the influenza virus infects the lungs. The result? The bacteria that live in the nose and throat can descend to the lungs and cause bacterial pneumonia. Who is most at risk? People over 50, infants, those with suppressed immune function or chronic diseases. Other complications include bronchitis, sinusitis and ear infections.

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COMPLICATIONS IN CHILDREN Studies show a link between the development of Reye’s syndrome and the use of aspirin for relieving fevers caused by the influenza virus. The disease involves the CNS and the liver and children exhibit symptoms of drowsiness, persistent vomiting and change in personality.

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PREVENTION The only proven method for preventing influenza is a yearly vaccination approximately 2 weeks before the “flu season” begins. Since the influenza virus is subject to genetic mutations with the HA and NA proteins, new vaccines that consist of different influenza strains need to be developed each year. Every year, the vaccine is trivalent, meaning that it provides resistance to three strains of influenza viruses. The vaccine consists of 2 influenza A virus pathogens and 1 influenza B pathogen.

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Practice good hygiene and personal health habits. Cover your mouth when while sneezing and wash your hands regularly as the virus spreads through aerosols. Public education campaigns are used to reduce infection rates Isolation of infected people is desirable but not always practical Immunisation

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THANK YOU..

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