Transcript H1N1/Swine Flu - Calgary Emergency Medicine

H1N1/SWINE FLU
Navpreet Sahsi
INFLUENZA
Globally 250,000 to 500,000 deaths per year
 In the US (per year)
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35,000 deaths
 > 200,000 hospitalizations
 $10 billion in lost productivity
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HISTORICALLY
Illness with influenza from pigs was first recongnized
during influenza pandemic of 1918 (40 – 50 million
deaths)
 1976 – Swine flu outbreak occurred in Fort Dix New
Jersey that caused more than 200 cases with serious
illness in several people and one death
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More than 40 million people vaccinated
 Program was stopped short after 500 cases of GBS and 30
reported deaths as direct result of vaccine
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Between 1958 – 2005, 37 additional cases of swine
influenza were reported
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Six cases of death
ZIMMER SM. NEJM 2009 361:279
2009 PANDEMIC
March/April 2009, outbreak of respiratory illnesses
first noted in Mexico, eventually identified as related
to H1N1 influenza
 April 17, 2009 – 2 cases in California of children in
neighbouring counties
 June 24 – WHO raised pandemic alert level to phase 6
– widespread community transmission on two
continents
 July 6 – 10,200 confirmed cases in Mexico with 119
deaths
 July 24 – 43,000 cases confirmed in US
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CHOWELL G. ET AL. NEJM 2009; 361: 274.
AT HOME
- June 10, 2009 – 47 cases in the Calgary area, and 2978
nationwide with 4 deaths
- August 9, 2009 – no longer keeping track of cases – 64
deaths nationwide, 6 in Alberta.
TRANSMISSION
Person – to –person
 Virus in present in respiratory secretions
 sneezing and coughing via large particle droplets
or by aerosolized small-particle droplets
 Contact with surfaces contaminated with
droplets
 Possibility of transmission from other bodily
fluids (eg. Diarrheal stool)
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PATIENT MYTHS
“You can get the swine flu from eating pork.”
 “I got my flu shot this winter, so I’m protected from the
swine flu.”
 “You can only get swine flu from direct contact with a
pig.”
 “Taking vitamins can protect against influenza.”
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YOU THINK YOU KNOW SWINE FLU?
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Incubation period?
A) 0 – 1 days
B) 1 - 4 days
C) 7 days
D) 14 days
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Answer:
Well, precise incubation period has not been
established but presumed to be…..
B) 1 – 4 days
INFECTIVITY?
A) One day prior to symptoms and one day post
symptoms
 B) One week prior to symptoms and one day post
symptoms
 C) One day prior to symptoms and one week post
symptoms
 D) One week prior to symptoms and one week
post symptoms
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C ) One day prior to symptoms and one week
post symptoms
CLINICAL MANIFESTATIONS
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Similar to those of seasonal influenza
GI findings have been more common than with seasonal
influenza
Commonly
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Fever
Cough
Sore throat
Malaise
Headache
Vomiting
Diarrhea
Arthralgias
Remember - Atypical presentations in infants, elderly,
immunocompromised
HIGH RISK GROUPS
Who?
HIGH RISK
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Children younger than 5 years
Age > 65
Less than 19 receiving long-term ASA therapy (Risk of
Reye’s syndrome after infx)
Pregnant Women
Chronic Diseases
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COPD
CVD (except isolated HTN)
CRF
Chronic Liver disease
DM
Immunosuppression – eg. HIV, transplant patients
Poor handling of resp. secretions – eg. CF, cerebral palsy, spinal
cord injuries, seizure disorders, NM disease
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What about obesity?
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Not officially recognized as a risk factor but a
disproportionate # of cases of severe H1N1 have been
reported without underlying conditions
COMPLICATIONS
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About 2 to 5% of confirmed cases in the US and Canada
have required hospitalization
6% in Mexico
Of hospitalized patients, large majority fall into high risk
category (75 – 85% in one study)
Many reported cases of rapidly progressive pneumonia,
respiratory failure, ARDS
Most complications similar to seasonal flu
URTIs (sinusitis, otitis media, croup)
LRTIs (pneumonia, brochiolitis, status asthmaticus)
Cardiac (myocarditis, pericardits)
Neuro (encephalopathy/encephalitis, febrile seizures, status
epilepticus)
 Toxic Shock syndrome
 Secondary bacterial pneumonia
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DIAGNOSIS
Who to test?
Basics
- Those who will require hospitalization
- Those who are at high risk for severe complications
(High risk group)
Important definitions (from CDC)
 Influenza-like illness (ILI) – fever (T > 37.8) with
cough or sore throat in absence of known cause
other than influenza
 Severe Respiratory Illness (SRI) – respiratory
symptoms including history of fever > 38, new
onset of cough or breathing difficulty, with severe
illness progression within first 72 hours
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Pneumonia, ARDS, encephalitis, or other severe and
life threatening complications
From Alberta Health Services
If mild ILI symptoms – NO LAB TESTING
 Mild ILI and high risk – NP swab considered
 Severe symptoms (admission to hospital) or SRI – NP
swab plus additional testing as appropriate
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Note turn around time for NP swab – 3 days
TREATMENT
Currently vast majority of strains appear
sensitive to neuraminidase inhibitors –
oseltamivir (Tamiflu) and zanamivir (Relenza)
 How soon to treat?
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A) ASAP
B) Within 24 hours
C) Within 48 hours
D) Within 96 hours
E) Within 7 days
Obviously A) therapy should begin as soon as
possible
 However, evidence of benefit in seasonal
influenza is strongest for treatment within 48
hours
 CDC still recommends therapy even after 48
hours of illness since some studies of hospitalized
patients have demonstrated benefit
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WHO GETS TAMIFLU?
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Basics
All hospitalized patients with confirmed or suspected
H1N1 infection
 Patients at increased risk for complications
 If you’re thinking about swabbing them, you should
at least be thinking about treating them.
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DOSING
Treatment - Tamiflu 75 mg PO BID x 5 days
 Prophylaxis – 75 mg PO OD x ?
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Relenza – 10 mg (2 puffs) BID x 5 days
 Prophylaxis – 10 mg OD
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WHAT ABOUT KIDS?
Tamiflu approved in US/Canada in individuals >
1 year of age, Relenza > 7 years old
 Limited safety data on kids < 1 year
 From Health Canada:
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“Health Canada’s Interim Order permits the expanded use
of oseltamivir as a treatment or prophylaxis for children
under 1 year of age, for infection caused by the pandemic
(H1N1) 2009 virus due to recent clinical data suggesting its
comparable safety profile identified in children over 1.”
Dosing in children – 2 mg/kg PO BID
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If no weight measures then by age:
0 – 3 months – 12 mg BID
 3 – 5 months – 20 mg BID
 6 – 11 months – 25 mg BID
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PREGGERS?
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True or False:
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Tamiflu and Relenza are safe in pregnant women
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True!!!
Pregnancy category C – meaning that clinical
studies not done. But no adverse events noted.
Health Canada states that current benefits
outweigh risks.
PREGGERS?
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When are pregnant women most susceptible to
H1N1 virus?
A)First Trimester
 B) Second Trimester
 C) Third Trimester
 D) Immediately post - partum
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Answer
 C) Third Trimester
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However, women are at increased susceptibility
during second trimester until about 4 weeks postpartum.
BREASTFEEDING?
You decide to treat a woman who is two weeks
post-partum that presents with worrysome
respiratory symptoms.
She asks you if it is safe to breast feed her
newborn baby while on antiviral therapy. What
do you tell her?
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Safe!!
“Due the anti-infective benefits of human milk for infants
and the low dosages of antiviral passed to the baby through
breastmilk, it is recommended that women continue to
breastfeed their baby when taking antiviral medications.” –
Health Canada
Dosing – same as in other adults – 75 mg PO BID
or 10 mg inhaled BID.
 “Preferred agent is Zanamivir (Relenza) in
pregnant/breastfeeding women although both
safe.” – Alberta Health Services
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REFERENCES
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Zimmer, SM. Historical Perspective – Emergence of Influenza A
(H1N1) Viruses. NEJM 2009; 361: 279 – 285.
Chowell, G. et al. Severe Respiratory Disease Concurrent with the
Circulation of H1N1 Influenza. NEJM 2009; 361: 674-679.
Public Health Agency of Canada
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www.phac-aspc.gc.ca/alert-alerte/swine-porcine/hp-index-eng.php
World Health Organization Influenza A (H1N1)
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www.who.int/csr/disease/swineflu/en.index.html
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Alberta Health Services
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www.calgaryhealthregion.ca/moh/professional.htm
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Epidemiology, clinical manifestations, and diagnosis of pandemic
H1N1 influena (“swine influenza”) www.uptodate.com
Treatment of pandemic H1N1 influenza (“swine influenza”)
www.uptodate.com