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8 Cards in this Set
- Front
- Back
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Three Kinds of Human Influenza
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-Most are Type A
-Highly contagious so most worrisome -Some are Type B/Type C -Not so transmissible, so not much of a problem -We will ignore Type B/C |
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How to Name a Virus
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-Named by type (ABC), place of origin, lab #, year, type of HA and NA proteins
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Symptoms of Influenza
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-Sudden high fever, achiness, fatigue
-May cause vomiting, diarrhea -Some inflammation, fluid build-up in lungs, can lead to secondary bacterial infections (pneumonia) -If severe, can cause death -Overall, not a high death rate (0.1%) |
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Transmission
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-Human-Human transmission via aerosol droplets
-By touching something with flu virus on it and then touching eye, nose or mouth -You are infectious from about one day BEFORE you get sick until about 5 days after you get sick -Cases peak in winter -Why? Indoors more, closer contact. Drier air, mucous membranes not as moist, efficient. Virus survives longer in cold weather, transmitted better |
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How Bad is "Normal" Flu
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Every year in the United States, on average:
-5% to 20% of the population gets the flu -more than 200,000 people are hospitalized from flu complications, and -about 36,000 people die from flu. |
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Influenza Pathogenesis
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Viral neuramindase (N) activity REDUCES VISCOSITY OF MUCOUS, allows virus to more easily reach and ATTACH TO CELLS via the viral hemagglutinin (H).
Infected cells are KILLED BY VIRAL REPLICATION. Thousands of new virus are released from each infected cell. Infection of cells in trachea and bronchi causes inflammation and leads to COUGH and TRACHEAL IRRITATION. The body’s immune cells respond to viral infection by releasing chemicals that cause FEVER, NASAL CONGESTION, and MUSCLE ACHES. DEATH OF CILIATED CELLS impairs the ciliary escalator, preventing viral extrusion and INCREASING SUSCEPTIBILITY TO SECONDARY BACTERIAL INFECTIONS. |
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Immunity to Flu
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-Develops after infection, but strain specific
-Only lasts a few years (?) -New vaccines produced each year against strains predicted to be common -Takes six months to ramp up vaccine production and distribution -Takes about two weeks to build immunity |
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Treatment for the Flu
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Drug Treatment
-One group blocks viral replication -However viruses develop resistance rather quickly -One group blocks neuraminidase activity Vaccine Treatment -Shot--Inactivated virus or one containing some parts of the Hemagglutinin or Neuraminidase protein (Remember antigenic?) -Nasal Spray--Weakened live virus -Could it return to former strong virus? |
