Transcript Who Is At Risk Of Exposure To H5N1 Avian Influenza

Who Is At Risk Of Exposure To
The Novel H1N1 Influenza Virus?
Tanya D. Graham, DVM, Diplomate ACVP
South Dakota State University
Animal Disease Research & Diagnostic Laboratory
Novel H1N1 Is Here To Stay…
Pandemics Come In Waves
• Pandemic viruses enter the population over multiple
time periods/seasons.
• Once people think the illness rates are subsiding they
stop paying attention to social distancing, hand
washing, and cough etiquette.
• Leads to new waves of influenza throughout the
community.
• Stay informed. CDC website is excellent source of
information.
Is The Pandemic H1N1 Really All
That Bad?
• No immunity to this new (novel) virus
• Proportion of people infected will be much higher
than typical seasonal flu
• A virus that is fatal in “only” 0.15% of cases but
infects twice the typical number of people will cause
~3 times more deaths (~100K) than seasonal flu will.
Lipstitch M, et al. Managing and Reducing Uncertainty in an Emerging Influenza Pandemic. N
Engl J Med 361(2):112-115. July 9, 2009.
Isn’t This Just More Media Hype?
• 1918 influenza pandemic infected > 25% of the world
population
• Estimated 50-100 million humans died
• 2009 H1N1 pandemic currently not anymore severe
than regular seasonal flu
Underlying
Disease
Present In At
Least Half Of
The Fatal
Cases
Who Is At Risk?
• Pigs, turkeys, and presumably other species are at risk
of catching the novel H1N1 influenza virus from an
infected human/other animals.
• People are risk of catching the novel H1N1 influenza
virus from other people with one exception:
▫ Groups with occupational risk of exposure to an
infected swine herd
 DVM
 Personnel working at swine facilities / hobby farmers
 State / federal employees involved in disease control
efforts
What Is The Worse Case Scenario
With This Pandemic H1N1 Strain?
• 40% of the U.S. population could catch the novel
H1N1 in next two years
• Several hundred thousand could die w/o vaccine
• Will Asian H5N1 (Bird Flu) virus swap genes with the
novel H1N1 and start yet another pandemic?
▫ The mortality rate of bird flu is ~60%
(six times worse than the 1918 pandemic virus)
Modes Of Transmission For ALL
Human Influenza Viruses
http://www.youtube.com/watch?v=qKiQA5e-fPg
Davidhazy, 2007
2 Main Routes Of Infection:
Inhalation & Transfer
• Inhalation of infectious droplets spread by sneezing,
coughing, talking, breathing
• Direct transfer of respiratory secretions to another
person (coughing, sneezing, talking at close distances
(ballistic droplets)
• Indirect transfer by contaminated hands (light
switch, door knob)
 Virus can survive 5 to 15 min on hands; 24 to 48 hrs on
inanimate surfaces
Short Range vs. Long Range &
Infectious Droplets
• Initial epidemiologists thought close
contact was required for transmission
▫ Based on studies demonstrating that
spacing beds in barracks or field hospitals
or desks in schools > 3 ft apart reduced
transmission rate.
Glover, 1920; Feigin, 1982.
Short Range vs. Long Range &
Infectious Droplets
• Recent evidence indicates transmission
may occur at distances of more than 3 ft
Xie, 2007; Wannamaker, 1954; Aintablian, 1998; Wong, 2004; Scales, 2003
• CDC has recently expanded definition of
“short range” to < 2 meters (~6.5 ft)
• CDC definition of “long range” > 2 meters
However!!!!
• No empirical evidence that increasing the
recommended distance for control measures to two
meters (6.5 feet) will result in lower influenza attack
rates.
• No experimental data exists that would “measure”
the risk of infections at a variety of distances from an
infected person.
• This is why it is so important to stay at home when
you are sick with the flu.
Minimizing The Risk Of Infection
• Regular hand washing
• Good respiratory hygiene (aka “Cough Etiquette”)
 Cover mouth/nose when coughing or sneezing
 Use tissue/sleeve/arm rather than hand
• Wear a mask (esp. if you are the sick one)
• Encourage co-workers / employees / friends & family to
stay home when they are sick
 Stay home until you are fever free for at least 24 hours
• Avoid crowded places / large gatherings
 Social distancing
• No single action protects completely
CDC’s Recent Recommendations
Concerning Face Masks
“There may be times during a pandemic
when you must be in a crowded setting
or in close contact with people who might be ill.
During such times, the use of a facemask or a
respirator might help prevent the spread
of pandemic flu.”
However!!!! No Scientific Studies Have
Determined If Face Masks Are Protective
 “The range of large droplets that fall to the ground is
generally no more than 3 feet.”
 No scientific data to support this statement
 Arose from a quote by Chapin-1910/repeated in literature
 Research in 1890s found
 Talking sprayed viable bacteria ~20 ft
 Whispering sprayed bacteria ~24 ft
 Combination of coughing, speaking, and sneezing carried
bacteria 40 ft
Should I Wear A Mask?
• Surgical masks
▫ Protect others from contaminants
generated by the wearer
▫ Do not protect wearer against inhalation
of hazardous material
Should I Wear A Mask?
• N95 & N100 Respirators—shield the wearer from
inhalational hazards
▫ Made of polypropylene wool felt, or fiberglass paper
▫ Particles become enmeshed within fibers
Should I Wear A Mask?
• To properly wear a respirator professional fit testing
is required
▫ Administer saccharin / banana oil / Bitrex
▫ The presence of taste, irritation, or smell = didn’t seal
properly
• N95 / other respirators do not work if you have
facial hair
▫ Cannot get an effective “seal” between the facial skin
and edge of the mask
These Are Not Your Parent’s
Mucous Membranes
• Mucous membranes line all organ systems that
communicate with air
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Eye
Nose
Mouth
Vagina
Urethra
Anus
• Important to wash your hands both before & after
using restroom
Novel H1N1 Is Here To Stay…
Current Diagnostic Tests Are Not
Very Sensitive
• Current tests capable of detecting novel A (H1N1)
virus from respiratory specimens have a low
sensitivity (40%-69%)
• Thus a positive result is useful but a negative result
does not rule out infection with novel H1N1
influenza virus
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5830a2.htm
What Are Antiviral Drugs
• “Antiviral drugs are prescription medicines (pills, liquid
or an inhaled powder) that fight against the flu by
keeping flu viruses from reproducing in your body.
• If you get sick, antiviral drugs can make your illness
milder and make you feel better faster.
• They may also prevent serious flu complications.
• Antivirals may be prioritized for persons with severe
illness or those at higher risk for flu complications.”
http://www.cdc.gov/h1n1flu/vaccination/public/vaccination_qa_pub.htm
Antivirals & Drug Resistance
• During the early stages of a pandemic
▫ Strain specific vaccines are not available
▫ Antiviral drugs are used to decrease mortality
and help prevent the spread of infection
• Drug resistance can occur in some people
Are Antivirals Useful In Children?
• Study involving 1766 children
▫ Effects of the neuraminidase inhibitors Tamiflu® and
Relenza® in children with seasonal influenza and
▫ Prevention of transmission to children in households.
• Conclusions
▫ Neuraminidase inhibitors provide a small benefit by
shortening the duration of illness in children with
seasonal influenza and reducing household
transmission.
▫ Little effect on asthma exacerbations or the use of
antibiotics
Shun-Shin M et al. Neuraminidase inhibitors for treatment and prophylaxis of influenza in children:
systematic review and meta-analysis of randomised controlled trials. BMJ 2009;339:b3172 August 10, 2009.
What’s The Deal With Tamiflu &
Teenagers?
• >50 individuals taking Tamiflu in Japan have died
• People acted erratically after taking Tamiflu
▫ There is growing concern among doctors and parents
in Japan over the drug's possible side effects on
children/teens
• FDA reviewed 103 cases involving Tamiflu
▫ 95% of the cases came from Japan
▫ Japan—24.5 million prescriptions (2001 )
▫ US—6.5 million prescriptions
What’s The Deal With Tamiflu &
Teenagers?
• FDA required Roche (makers of Tamiflu) to put a
caution on the label—look out for strange behavior.
▫ Updated in March of 2008 to indicate that some cases
were fatal (suicides).
• Not all cases of nervous system disorder will be
caused by the use of antivirals.
▫ Delirium disorders associated with influenza occur in
about 4 of every 100,000 flu patients in US without the
use of any drugs.
Should I Or My Family Receive
Antiviral Treatment? Vaccinations?
• Talk with your physician to determine what course of
treatment is best for you & your child
▫ Consider having this conversation during schoolmandated physicals or other appointments with your
doctor before flu season strikes
• Monitor the CDC website for new information about
the novel H1N1 pandemic virus
• Always ask questions!
When Will A Vaccine Be Available?
• The seasonal flu vaccine will not provide protection
against the novel H1N1 pandemic strain
• A vaccine for the novel H1N1 strain is being produced
now-may be available around Thanksgiving
• Both seasonal flu & novel H1N1 vaccines can be given at
the same time, in different anatomic locations.
• All persons currently recommended for seasonal
influenza vaccine, including those aged ≥65 years, should
receive the seasonal vaccine as soon as it is available.
• There are no changes in the recommendations for
pneumococcal vaccines (i.e. if you are in the target group
you should still get the pneumococcal vaccination too)
CDC Expects Initial Vaccine Shortage*
This Group Will Receive Vaccine First
Not in particular order
•
•
•
•
•
Pregnant women
People who live with/care for children < 6 month old
Health care / emergency medical services personnel
Children 6 months to 4-year-olds
Children 5 to 18-year-olds w/ chronic medical
conditions
Followed by
• Vaccination of everyone 25 to 64 years old
Followed by
• Vaccination of 65+ years old
So If I Catch It, How Long Do I
Have To Stay At Home?
• Rule for most people:
“CDC recommends that people with influenza-like
illness remain at home until at least 24 hours after
they are free of fever (100° F)…without the use of
fever-reducing medications.”
If I Survive Am I Immune?
 If you become sick and survive infection with the
circulating pandemic strain of virus you can treat the sick
without worry of becoming ill again (as long as the virus
has not significantly evolved into a new strain).
 State and local public health departments should be able to
determine the nature of the strains circulating locally and
regionally through their surveillance activities.
 If you did not become sick in a previous wave you may
still be susceptible during subsequent waves.
 Regardless, it is always best to use basic infection control
precautions.
CDC EXCELLENT
SOURCE OF
CURRENT
INFORMATION
Questions?