1 case management of suspect human avian influenza infection part 1: background information on...

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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