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Avian Influenza
Aka: Avian Influenza, Avian Influenza A, Bird Flu, Asian H5N1, Influenza A H5N1
- See Also
- Influenza
- Background
- Historical Avian Influenza Outbreaks
- Spanish Flu (H1N1): 1918-1919 (40-100 Million deaths)
- Asian Flu (H2N2): 1957 (2 million deaths)
- Hong Kong Flu (H3N2): 1968 (1 million deaths)
- Recent strains
- Asian strain (H9N2): 1998
- Netherlands (H7N7):2003
- Avian Influenza A (H5N1, Bird Flu)
- Currently active Avian Influenza Strain
- Expected to be next Influenza pandemic
- 1997: 18 cases (6 deaths) in Hong Kong
- 2004-5: 137 cases (70 deaths) Southeast Asia, China
- Outbreak associated with more virulent Z-strain
- 2006: 228 cummulative cases and 130 deaths
- Total cases thought to be much higher
- Mild cases are likely underestimated
- Pathophysiology
- Life-cycle of Avian Influenza A
- Avian Influenza A shed in waterfowl (esp. ducks)
- Poultry and pigs become infected
- Animal handlers become infected
- Exposure to infected animals is primary source
- Human-to-human transmission requires high exposure
- Virulence
- Immune reaction to virus is intense
- Results in Cytokine Storm
- Risk Factors: Exposures
- Asian poultry animal handlers
- Asian animal markets, poultry farms, cock fights
- Cleaning up areas with poultry feces present
- Contact with fertilizer contaminated with bird feces
- Symptoms: Onset 2-5 days after exposure
- Fever
- Cough
- Respiratory distress (associated with Viral Pneumonia)
- Watery Diarrhea
- Diagnosis: Pharyngeal swab for H5-Specific RNA
- Preferred over nasal swab
- Detection by Reverse transcriptase PCR
- Labs
- Complete Blood Count with Leukopenia
- Imaging
- Chest XRay
- Nonspecific infiltrates by 7 days post-fever onset
- Management
- Tamiflu
- See Neuraminidase Inhibitors (also Relenza)
- Treatment: 75 mg PO bid for 5 days
- Must be started within 48 hours of onset
- Reduces illness severity by 40%
- Post-exposure Prophylaxis: 75 mg PO qd x7-10 days
- Resistance rates are currently low
- Other anti-viral agents
- Amantadine and Ramantadine resistance is high
- Other experimental agents
- Statins
- May reduce Cytokine Storm reaction
- Improves survival in Septic Shock
- Only effective if started prior to infection
- Prevention
- Avoid exposure
- See Risk Factors above
- H5N1 Vaccine
- Undergoing human trials
- Not expected to be available for several years
- Resources
- CDC Avian Flu Information
- http://www.cdc.gov/flu/avian/gen-info/facts.htm
- WHO Avian Influenza information
- http://www.who.int/csr/don
- U.S. Department of Health and Human Services
- http://www.pandemicflu.gov
- References
- Fauci (2006) Emerg Infect Dis 12:73-7 [PubMed]
- Juckett (2006) Am Fam Physician 74(5):783-90 [PubMed]
- Monto (2005) N Engl J Med 352:323-5 [PubMed]