Avian flu

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Avian flu

• By Sona Hamelin

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History

• The human influenza A virus was discovered in
  1933 soon after Shope succeeded in isolating
  swine influenza A virus in 1931
• Influenza outbreaks were noticed as soon as 1899

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Influenza outbreak
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Viruses

• Obligatory intracellular parasites
• Contain single type of nucleic acid (either DNA
  or RNA)
• Contain protein coat, some contain envelop and
  spikes.

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Structure of Influenza virus
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N and H spikes

• H spikes stand for hemagglutinin
• N spikes stand for neurominidase

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Influenza types

• Influenza viruses are classified into major
  groups according to the antigens of their
  protein A, B, C
• The A-type viruses are responsible for major
  pandemics
• Avian influenza is influenza carried by the birds

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Viral infection can be blocked by neutralizing
antibodies
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Virus-infected cells
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Function if the type 1 interferons
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Effector T cell
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Antigenic drift
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Antigenic shift
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T and B cells interactions

• Two disulfide linked subunits HA-1, and HA-2
• T cell specific for the M protein can help B
  cells specific for HA, so that the relative lack
  of HA-specific T cells may not limit the level of
  help delivered to HA-specific B cells

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Sites of recognition
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Transmission from birds to human

• Infected birds shed flu virus in their saliva,
  nasal secretions, and feces.
• Transmission to humans happen through
• Direct contact with secretions from infected
  birds
• Contaminated food, water, equipment and clothing
• Clinically normal waterfowl and sea birds may
  introduce the virus into flocks
• Broken contaminated eggs may infect chicks in the
  incubator

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Symptoms

• High fever
• Pneumonia
• Eye infection
• Acute respiratory distress
• Influenza like symptoms
• Cough
• Sore throat
• Muscle ache

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Laboratory findings

• Leukopenia (particularly lymphopenia)
• Mild to moderate thrombocytopenia
• Slightly or moderately elevated aminotransferase
  levels
• Hyperglycemia
• Elevated creatinine levels

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immunization

• The "flu shot - an inactivated vaccine
  (containing killed virus) that is given with a
  needle, usually in the arm.
• The nasal-spray flu vaccine - a vaccine made with
  live, weakened flu viruses that do not cause the
  flu

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Treatment

• Antiviral medications (oseltamivir and zanamivir)
  that will
• Reduce the severity and duration of symptoms
  caused by infection with influenza A or B virus
• Shorten the length of the illness
• Control outbreaks of the flu in nursing homes
• Reduce the spread of the virus to people at high
  risk for severe complications of the flu
• Reduce complications from the flu

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Summary

• Avian flu is a virus carried by birds
• Avian virus contain H and N spikes on their
  surface
• Avian virus interact with T and B cells
• There is not a permanent vaccine since influenza
  virus A changes its structures
• Antiviral drugs can reduce symptoms

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Work cited

• Villarreal, Luis P. (2005). Viruses and The
  Evolution of Life. Washington, D.C. ASM
• The Writing Committee of the Health Organization.
  (2005). Avian Influenza A (H5N1) Infection in
  Humans. The New England Journal of Medicine, 353,
  1374-1385. Retrieved October 11, 2005 from the
  World Wide Web http//content.nejm.org/cgi/conten
  t/full/353/13/1374
• Male, D., Champion, B., Cooke, A. (1989).
  Advanced Immunology. Hong Kong Mandarin Offset.
• Kolata, G. (1999). Flu The Story of The Great
  Influenza Pandemic of 1918 and The Search for The
  Virus That Cause. New York Farrar, Straus and
  Giroux.
• Ahmad, K. (2004). Increased Asian Collaboration
  in Fight against Avian Flu, Science Direct, 5,
  (1), 9. Retrieved October 11, 2005 from the World
  Wide Web http//www.sciencedirect.com
• Appenzeller, T. (2005). Tacking The Next Killer
  Flu. National Geographic, 208, 2-31.
• Avian Influenza Frequently asked questions.
  (2005). World Health Organization. Retrieved
  September 30, 2005 from the World Wide Web
• http//www.who.int/csr/disease/avian_influenza/av
  ian_faqs/en/index.html