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FLU. Orthomyxoviridae. Eight segmented pieces of RNA, a structure that permits the introduction of new RNA. This is called genetic reassortment. This is called antigenic shift.
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Eight segmented pieces of RNA, a structure that permits the introduction of new RNA. This is called genetic reassortment. This is called antigenic shift. • The hemagglutinin spikes which provide viral attachment to cell membranes. They are strain specific antigens that mutate frequently because of inefficient proofreading by RNA polymerase. This is called antigenic drift. • And ditto for the Neuraminidase spike, which provides release from cell membranes
FAQ’s • Type A: The Main Player • It causes annual outbreaks • It mutates easily. This is called antigenic drift and is why the vaccine changes every year, usually causing an epidemic affecting 10% to 20% of the population. • It is susceptible to RNA reassortment, where a portion of avian influenza RNA is inserted. This is called antigenic shift and is responsible for pandemics or infections occurring over a wide geographic area and affecting a high proportion of the population. • It is characterized by the H and N antigens.
Five Pandemics • 1918: Possibly an avian influenza strain that adapted to infect humans. • 1957 and 1968: A human/avian reassortment strain. • 2009: A human/swine/avian reassortment virus.
Transmission • Person to Person • Viral shedding—day prior to symptom onset—5-7 days after symptom onset • Can get from pigs not from eating pork
Vaccination • EVERYONE >6months and older • IM (inactivated) Intranasal (live attenuated) • Intranasal NOT USED IN: chronic disease, immunsuppression, pregnancy, prior h/o GB from prior vaccinations • SMALL AMOUNTS of EGG in each • Anaphylaxis is rare • What do we carry? • Efficacy: 50%-80% rate of protection if closely matched
Vaccine Three strains: (always A-A-B) this year: -A-California h1n1-”like” virus -A-Perth h3n2 ”like” virus -B Brisbane Every year the strains are selected based on worldwide surveillance for most active strains– a little guess-work involved
Suspected Cases • Fevers, Myalgias • TEST—flu swab, nasal
Treatment & PPX • Oseltamivir: TAMIFLU • Zanamavir: Ralenza • Rx for Type A &B • Low levels of resistance • In 48 hours TREAT (as per Dr. Chung) • PPX: NH Residents within 48 h, Case by case Babies, pregnant women
PRACTICAL CONCERNS • HOW TO ORDER THE VACCINE • HOW TO BILL FOR IT • ALLERGIES: EGGS!!! Relative Contraindication • No inhaled form of vaccine here • Rapid antigen—Nasal swab in 6th floor Micro • ?????s