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.

• 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.

Type B and Type C

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.

SWINE FLUWhat does this mean?

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

“I don’t want it today Doc…”

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

caseBabies, 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