Bird Flu Virus

bird flu


  • Bird flu or Avian Influenza (A1) is a contagious disease of bird raging from mild to serve form of illness.
  • Some forms of bird flu infections can cause illness to humans.
  • Bird flu is caused by an influenza A virus.
  • The outbreaks affecting some Asian countries have been caused by influenza A/H5N1 virus. It can also cause severe infection in humans.


  • First identified in Italy in 1878, highly pathogenic avian influenza is characterized by sudden onset of severe disease, rapid contagion, and a mortality rate that can approach 100% within 48 hours.
  • Human deaths from avian influenza were unknown until 1997, when six people in Hong Kong died from the particularly virulent H5N1 strain.
  • In January 2004, a new major outbreak of H5N1 avian influenza surfaced again in Vietnam and Thailand’s poultry industry, and within weeks, spread to ten countries and religions in Asia including Indonesia, South Korea, Japan, and China.
  • In February 2004, avian influenza virus was detected in pigs in Vietnam, increasing fears of the emergence of new variant strains.
  • Fresh outbreaks in poultry were confirmed in Ayutthaya and Pathumthani provinces of Thailand, and Chaohu city in Anhui, China, in July 2004.
  • In North America, the presence of avian influenza was confirmed at several poultry farms in British Columbia in February 2004.
  • In August 2004 avian flu was confirmed in Kampung Paris, Kelantan, Malaysia. Two chickens were confirmed to be carrying H5N1.

Etiologic Agent:

  • The causative agent is the avian influenza (A1) virus. A1 viruses all belong to the influenza virus, a genus of the Orthomyxoviridae family and are negative-stranded, and segmented.

Modes of Transmission:

  1. Avian influenza spreads in the air and in manure. Wild fowl often acts as resistant carrier spreading it to more susceptible domestic stocks.
  2. It can also be transmitted through contaminated feeds, water, equipment, and clothing; however, there is no evidence that the virus can survive in well cooked meat.
  3. Cats are also thought to be possible infection vectors for H5N1 strains of avian flu.
  4. While avian influenza spreads rapidly among birds, it does not infect humans easily, and there is no confirmed evidence of human-to-human transmission. Of the 15 subtypes known, only subtypes H5 and H7 are known to be capable of crossing the species barrier.

Incubation Period:

  • The incubation period is three to five days.

Signs and Symptoms:

  1. Symptoms in animals vary, but virulent strains can cause death within a few days.
  2. The symptoms of avian influenza in humans following exposure to bird flue infected chicken patient develops:
    • fever, body weakness or muscle pain, sore throat, cough, sore eyes, may have difficulty of breathing in severe cases

Prevention and Treatment:

Avian influenza in humans can be detected reliably with standard influenza tests. Antiviral drugs are clinically effective in both preventing and treating the disease. Vaccines, however, taken at least four months to produce and must be prepared for each subtype.

  1. Wash hands thoroughly with soap and water before and after handling live and dressed chicken.
  2. Cook chicken thoroughly.
  3. Do not sell live chickens and other birds in the market while there is a threat of bird flu.
  4. Do not let chickens roam freely. Keep them in cages or pens.
  5. Do not place chicken, ducks and pigs together in one area, cage or pen.
  6. Do not catch, get near or keep in captivity wild birds.
  7. Report to the nearest agricultural/veterinary office any unusual death or illness of chickens and other birds.
  8. Report to the nearest local health centers any case of respiratory illness with history of exposure to sick or dead chickens and other birds.
  9. Individuals at risk are those directly exposed to sick chicken and other birds. The government thereby advises prospective travelers to countries affected with bird flu not to go to bird parks, poultry farms and markets where live chicken and other birds are sold.



Baguio Health Department – DOH

Handbook of Common Communicable and Infectious Diseases – 2006 Ed

World Health Organization

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