Influenza

State of Alaska, Division of Public Health

Section of Epidemiology

Donna Fearey, ANP, MSN

October 2013

Overview

• Introduction to influenza viruses

• How do influenza viruses change?

• What is influenza disease?

• What are the tools for prevention?

• What surveillance is being conducted?

• Discuss novel flu in the news

• What conditions are necessary for an influenza pandemic?

Influenza Viruses

• Influenza A

• Influenza B

• Influenza C

Reservoir for Influenza A

Influenza A Subtyped based on

proteins on surface:

• hemagglutinin (H)

• neuraminidase (N)

A/California/7/2009 (H1N1)pdm09-like virus

How the Flu Virus Can Change

Antigenic Drift

• Small changes in the virus that happen

continually over time

How the Flu Virus Can Change

Antigenic Shift

• An abrupt, major change in the viruses

which result in a new influenza A

subtype

• Gradual Adaptation

• Reassortment

Influenza Disease • Respiratory tract infection

• Transmission by respiratory droplet; airborne possible

• Incubation period: 1-4 days

• Period of infectiousness: from day before or day of illness onset, lasts 3-5 days

What Can We Do to Protect Ourselves

and Prevent Spread of Influenza?

• Wash your hands often with soap and water or use hand sanitizer

• Cover your mouth when you cough or sneeze

• Avoid touching your eyes, nose, and mouth

• Stay home if you are ill

Get An Annual Influenza Vaccination

Seasonal Influenza Vaccine

Recommended for everyone over the age of 6 months

Antiviral Drugs for Influenza

• Neuraminidase

Inhibitors

• Oseltamivir

• Zanamivir

U.S. Influenza Surveillance

Alaska Influenza Surveillance

http://www.epi.hss.state.ak.us/id/influenza/influenza.jsp

Avian Influenza A (H7N9)

• Sporadic infections in

humans; many with

poultry exposure

• No evidence of

sustained person-to-

person spread of the

H7N9 virus

H3N2v • Influenza viruses that normally circulate in

pigs are called “variant” viruses when they

are found in people

• Associated with prolonged exposure to pigs

at agricultural fairs

• Symptoms are similar to those of seasonal

flu viruses

Ingredients For a Pandemic

• A new influenza virus to which the population has little immunity

• Ability of the virus to replicate in humans and cause disease

• Efficient and sustained person-to-person transmission

2009 H1N1 Pandemic

• 1st case in US in April 15, 2009. WHO

declared pandemic June 11, 2009

• Quadruple-reassortant virus originated from

four different influenza virus sources

• Vaccine available in October (targeted

groups)

Section of Epidemiology

During business hours: 1-907-269-8000

After hours:1-800- 478-0084 http://www.epi.hss.state.ak.us/default.jsp

2013-2014 Flu Vaccine

• A/California/7/2009 (H1N1)pdm09-like

virus;

• A(H3N2) virus antigenically like the cell-

propagated prototype virus

A/Victoria/361/2011;

• B/Massachusetts/2/2012-like virus.

• The quadrivalent vaccines contain above

three viruses and a B/Brisbane/60/2008-like

virus.

Middle East Respiratory

Syndrome (MERS)

• Caused by a coronavirus called MERS-

CoV.

• Cases have been linked to four countries in

or near the Arabian Peninsula.

• Has spread from ill people to others through

close contact, but not in a sustained way

• The situation is still evolving.