1 case management of suspect human avian influenza infection part 1: background information on...
TRANSCRIPT
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Case Management of Suspect Human Avian Influenza Infection
Part 1: Background information on clinical features and management of
avian influenza
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Learning Objectives
• Recognize clinical features of H5N1 in humans
• Understand how information about the patient before onset of illness can help you suspect infection
• Know the types of treatment options available
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Part 1 Session Overview
• Clinical features
• Epidemiologic information
– Risk for infection
– Transmission
• Current antiviral medications
• Group exercise
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Illness Scenario
• 5-year-old Mg Win was sick for three days– Fever– Watery diarrhea– Headache– Cough– Short of breath
• No one else sick• Mg Win and a friend play with chickens
Question: Is this avian influenza?
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Clinical Features
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General InformationHuman
influenza
Avian
influenza
Vulnerable
Age Groups
• All ages affected
• Highest rates in children < 5 years
• Most complications in elderly >60 years
• Children < 5 years
• Healthy young adults
• Adolescents
Time from exposure to illness
• Mean 2 days
• Range: 1 – 5 days
• Mean 2 – 3 days
• Range: 2 – 10 days
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Signs and Symptoms
Human Influenza Avian Influenza (H5N1)
Type of infection Upper respiratory Lower respiratory
Fever Yes Yes
Headache Yes Yes
Cough Yes Yes
Respiratory symptoms
Varies; sore throat to difficulty breathing
Difficulty breathing, crackles, increased
respiratory rate
Gastrointestinal symptoms
Rare: Children, elderly Rare: Variable, watery diarrhea, vomiting,
abdominal pain
Recovery 2-7 days Longer
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Unusual Presentations
• Knowledge of avian influenza infection in humans changes as we learn more
• Unusual symptoms– Absence of respiratory symptoms– Severe watery diarrhea– Loss of consciousness
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Complications
Seasonal Influenza• Ear infection, sinusitis• Bronchitis, bronchiolitis• Pneumonia
– viral or secondary bacterial
• Exacerbation of chronic conditions
• Muscle inflammation• Neurologic Disease
– Seizures– Brain inflammation– Reye’s syndrome
Avian Influenza• Almost all develop
pneumonia• Acute Respiratory
Distress Syndrome (ARDS)
• Multiorgan failure• Encephalitis
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Laboratory Findings
Commonly associated with avian influenza:
• Drop in white blood cell count (lymphocytes)
• Mild to moderate drop in blood platelet count
• Increased aminotransferases (Liver enzymes)
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Question:
Do you think Mg Win has signs and symptoms of avian influenza?
Why or why not?
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Epidemiologic Information
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Risk for Infectionfrom Animals
Within 10 days before symptoms begin:
• Close contact with live, sick, or dead birds
• In setting with confined birds
• Contact with contaminated surfaces
• Ingestion of uncooked infectious poultry
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Risk for Infection from Humans
• Uncertain risk of person-to-person spread
• Within 10 days before symptoms begin:– Face-to-face contact
– Touching or within 1 meter of suspected or diagnosed H5N1 patient without proper precautions
– Touching or being within 1 meter of a person who has severe pneumonia or dies from an acute respiratory illness without proper precautions
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Question:
Do you think that Mg Win is at risk for avian influenza H5N1 infection?
Why or why not?
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Routes of Transmission
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Risk Factors
• Direct contact with birdsRisk Factors:
– Playing with birds– Working with birds– Preparing birds for meals
• Contaminated water
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Routes of Transmission
• Indirect contact– Infected materials, surfaces
• Person-to-person rare at present
• Eating undercooked or raw bird products– Meat, eggs, blood
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Question:
Has Mg Win had an exposure that could lead to
transmission?
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Using All of The Information
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A Clinician Should Suspect H5N1 Infection if a Patient Has:
• Severe acute respiratory illness with
• Exposure 10 days before symptoms to:– Suspect / diagnosed avian H5N1 patient– Poultry or Wild Birds OR
• Direct contact with birds OR
• Residence in an area with known H5N1 activity in poultry
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Case Scenario
• 5-year-old Mg Win is sick for three days
– Fever– Watery diarrhea– Headache– Cough
• No one else sick
• The patient and a friend play with and hold chickens
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Question:
Would you suspect avian influenza H5N1 infection? Why or why not?
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Current Antiviral Treatment
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Neuraminidase Inhibitor
• Neuraminidase enzyme breaks bond between infected cell and newly formed virus
• Inhibitor prevents enzyme from breaking bond and releasing virus
• Virus particles cannot infect other cells
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Neuraminidase Inhibitor
• Two drugs available
– Oseltamivir (Tamiflu®) and Zanamivir (Relenza ®)
– Should be given as soon as possible
– Effective for treatment and prevention
– Used for seasonal or avian influenza
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Oseltamivir
Dosage for seasonal influenza
Adults: 75 mg twice a day for 5 days
Children:
<1 year, not studied adequately< 15 kg - 30 mg twice a day for 5 day>15 kg to <23 kg - 45 mg twice a day for 5 days>23 kg to <40 kg - 60 mg twice a day for 5 days>40 kg - 75 mg twice a day for 5 days
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Oseltamivir
Dosage for avian influenza
• Best dosage for H5N1 unknown– Longer treatment (7 to 10 days) OR– Higher doses (150 mg)
• Dosage for prevention– Once daily for 7 to 10 days after last exposure
• Side Effects– Nausea and vomiting– Skin rash
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Oseltamivir
• Effectiveness in seasonal influenza– Reduces influenza symptoms 1 - 3 days– Reduces lower respiratory tract complications,
pneumonia, and hospitalization
• Cautions- Consider Risk versus Benefits– People with kidney disease (adjust dose)– Pregnant or nursing females
• Resistance – Detected in several avian influenza H5N1 patients
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Zanamivir
• Inhaled by mouth via special device
• May be used for > 5 years of age
• Treatment dosage– Once in morning and night, 5 days
• Side effects– Wheezing, and breathing problems
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Zanamivir
• Effectiveness in seasonal influenza– Reduces influenza symptoms 1 - 3 days– Reduces lower respiratory tract complications
• Consider Risk vs. Benefit– People with chronic respiratory disease – Pregnant or nursing females
• Resistance– Not identified in human H5N1 infections– Active against Oseltamivir resistant H5N1
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Other Treatments?
• Amantadine and Rimantadine– H5N1 resistant in some isolates– Not as effective as
neuraminidase inhibitors
• Corticosteroids– Low dose for sepsis– Unclear if high dose useful– Risk of side effects
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Question:
What would you do at this stage ?
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Part 1 Summary
• Ask about recent exposure and contact with humans or animals that may have had avian influenza H5N1 infection
• Laboratory can confirm H5N1, but you should not wait
• Individuals with avian influenza H5N1 infection may not have respiratory symptoms
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Questions?
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Case Study Exercise
Background information on clinical features and management of avian
influenza