   #copyright

H5N1

2007 Schools Wikipedia Selection. Related subjects: Health and medicine

   CAPTION: H5N1

     * Influenza A virus subtype H5N1
     * Genetic structure
     * Infection
     * Global spread

          + in 2006

     * Social impact
     * Pandemic

   WHO pandemic phases
    1. Low risk
    2. New virus
    3. Self limiting
    4. Person to person
    5. Epidemic exists
    6. Pandemic exists

   Influenza A virus subtype H5N1, also known as A(H5N1) or H5N1, is a
   subtype of the Influenza A virus that can cause illness in humans and
   many other animal species. A bird-adapted strain of H5N1, called HPAI
   A(H5N1) for "highly pathogenic avian influenza virus of type A of
   subtype H5N1", is the causative agent of H5N1 flu, commonly known as "
   avian influenza" or "bird flu". It is endemic in many bird populations,
   especially in Southeast Asia. One strain of HPAI A(H5N1) is spreading
   globally after first appearing in Asia. It is epizootic (an epidemic in
   nonhumans) and panzootic (affecting animals of many species, especially
   over a wide area), killing tens of millions of birds and spurring the
   culling of hundreds of millions of others to stem its spread. Most
   mentions of "bird flu" and H5N1 in the media refer to this strain.

   HPAI A(H5N1) is an avian disease. There is no evidence of efficient
   human-to-human transmission or of airborne transmission of HPAI A(H5N1)
   to humans. In almost all cases, those infected with H5N1 had extensive
   physical contact with infected birds. Still, around 60% of humans known
   to have been infected with the current Asian strain of HPAI A(H5N1)
   have died from it, and H5N1 may mutate or reassort into a strain
   capable of efficient human-to-human transmission. In 2003,
   world-renowned virologist Robert Webster published an article titled
   "The world is teetering on the edge of a pandemic that could kill a
   large fraction of the human population" in American Scientist. He
   called for adequate resources to fight what he sees as a major world
   threat to possibly billions of lives. On September 29, 2005, David
   Nabarro, the newly-appointed Senior United Nations System Coordinator
   for Avian and Human Influenza, warned the world that an outbreak of
   avian influenza could kill anywhere between 5 million and 150 million
   people. Experts have identified key events (creating new clades,
   infecting new species, spreading to new areas) marking the progression
   of an avian flu virus towards becoming pandemic, and many of those key
   events have occurred more rapidly than expected.

   Due to the high lethality and virulence of HPAI A(H5N1), its endemic
   presence, its increasingly large host reservoir, and its significant
   ongoing mutations, the H5N1 virus is the world's largest current
   pandemic threat, and billions of dollars are being spent researching
   H5N1 and preparing for a potential influenza pandemic. At least 12
   companies and 17 governments are developing pre-pandemic influenza
   vaccines in 28 different clinical trials that, if successful, could
   turn a deadly pandemic infection into a nondeadly one. Full-scale
   production of a vaccine that could prevent any illness at all from the
   strain would require at least three months after the virus's emergence
   to begin, but it is hoped that vaccine production could increase until
   one billion doses were produced by one year after the initial
   identification of the virus.

Genetics

   The H in H5N1 stands for "Hemagglutinin", as depicted in this molecular
   model.
   Enlarge
   The H in H5N1 stands for " Hemagglutinin", as depicted in this
   molecular model.

   The first known strain of HPAI A(H5N1) (called A/chicken/Scotland/59)
   killed two flocks of chickens in Scotland in 1959; but that strain was
   very different from the current highly pathogenic strain of H5N1. The
   dominant strain of HPAI A(H5N1) in 2004 evolved from 1999 to 2002
   creating the Z genotype. It has also been called "Asian lineage HPAI
   A(H5N1)".

   Asian lineage HPAI A(H5N1) is divided into two antigenic clades. "Clade
   1 includes human and bird isolates from Vietnam, Thailand, and Cambodia
   and bird isolates from Laos and Malaysia. Clade 2 viruses were first
   identified in bird isolates from China, Indonesia, Japan, and South
   Korea before spreading westward to the Middle East, Europe, and Africa.
   The clade 2 viruses have been primarily responsible for human H5N1
   infections that have occurred during late 2005 and 2006, according to
   WHO. Genetic analysis has identified six subclades of clade 2, three of
   which have a distinct geographic distribution and have been implicated
   in human infections: Map
     * Subclade 1, Indonesia
     * Subclade 2, Middle East, Europe, and Africa
     * Subclade 3, China"

Terminology

   H5N1 isolates are named as in this actual HPAI A(H5N1) example,
   A/chicken/Nakorn-Patom/Thailand/CU-K2/04(H5N1):
     * A stands for the species of influenza (A, B or C).
     * chicken is the species the isolate was found in
     * Nakorn-Patom/Thailand is the place this specific virus was isolated
     * CU-K2/04 is the identifier distinguishing it from other isolates at
       the place of the specimen it was isolated from with 04 representing
       the year 2004
     * H5 stands for the fifth of several known types of the protein
       hemagglutinin.
     * N1 stands for the first of several known types of the protein
       neuraminidase.

   (Other examples: A/duck/Hong Kong/308/78(H5N3), A/avian/NY/01(H5N2),
   A/Chicken/Mexico/31381-3/94(H5N2), and A/shoveler/Egypt/03(H5N2)).

   As with other avian flu viruses, H5N1 has strains called "highly
   pathogenic" (HP) and "low-pathogenic" (LP). Avian influenza viruses
   that cause HPAI are highly virulent, and mortality rates in infected
   flocks often approach 100%. LPAI viruses have negligible virulence, but
   these viruses can serve as progenitors to HPAI viruses. The current
   strain of H5N1 responsible for the deaths of birds across the world is
   an HPAI strain; all other current strains of H5N1, including a North
   American strain that causes no disease at all in any species, are LPAI
   strains. All HPAI strains identified to date have involved H5 and H7
   subtypes. The distinction concerns pathogenicity in poultry, not
   humans. Normally a highly pathogenic avian virus is not highly
   pathogenic to either humans or non-poultry birds. This current deadly
   strain of H5N1 is unusual in being deadly to so many species.

Genetic structure and related subtypes

   The N in H5N1 stands for "Neuraminidase", as depicted in this ribbon
   diagram.
   Enlarge
   The N in H5N1 stands for " Neuraminidase", as depicted in this ribbon
   diagram.

   H5N1 is a subtype of the species Influenza A virus of the
   Influenzavirus A genus of the Orthomyxoviridae family. Like all other
   influenza A subtypes, the H5N1 subtype is an RNA virus. It has a
   segmented genome of eight negative sense, single-strands of RNA,
   abbreviated as PB2, PB1, PA, HA, NP, NA, M and NS.

   HA codes for hemagglutinin, an antigenic glycoprotein found on the
   surface of the influenza viruses and is responsible for binding the
   virus to the cell that is being infected. NA codes for neuraminidase,
   an antigenic glycosylated enzyme found on the surface of the influenza
   viruses. It facilitates the release of progeny viruses from infected
   cells. The hemagglutinin (HA) and neuraminidase (NA) RNA strands
   specify the structure of proteins that are most medically relevant as
   targets for antiviral drugs and antibodies. HA and NA are also used as
   the basis for the naming of the different subtypes of influenza A
   viruses. This is where the H and N come from in H5N1.

   Influenza A viruses are significant for their potential for disease and
   death in humans and other animals. Influenza A virus subtypes that have
   been confirmed in humans, in order of the number of known human
   pandemic deaths that they have caused, include:
     * H1N1, which caused " Spanish flu" and currently causes seasonal
       human flu
     * H2N2, which caused "Asian flu"
     * H3N2, which caused "Hong Kong flu" and currently causes seasonal
       human flu
     * H5N1, the world's major current pandemic threat
     * H7N7, which has unusual zoonotic potential and killed one person
     * H1N2, which is currently endemic in humans and pigs and causes
       seasonal human flu
     * H9N2, which has infected three people
     * H7N2, which has infected two people
     * H7N3, which has infected two people
     * H10N7, which has infected two people

Low pathogenic H5N1

   Low pathogenic avian influenza H5N1 (LPAI H5N1) also called "North
   American" H5N1 commonly occurs in wild birds. In most cases, it causes
   minor sickness or no noticeable signs of disease in birds. It is not
   known to affect humans at all. The only concern about it is that it is
   possible for it to be transmitted to poultry and in poultry mutate into
   a highly pathogenic strain.
     * 1975 – LPAI H5N1 was detected in a wild mallard duck and a wild
       blue goose in Wisconsin.

     * 1981 and 1985 – LPAI H5N1 was detected in ducks by the University
       of Minnesota conducting a sampling procedure in which sentinel
       ducks were monitored in cages placed in the wild for a short period
       of time.

     * 1983 – LPAI H5N1 was detected in ring-billed gulls in Pennsylvania.

     * 1986 - LPAI H5N1 was detected in a wild mallard duck in Ohio.

     * 2005 - LPAI H5N1 was detected in ducks in Manitoba, Canada.

   "In the past, there was no requirement for reporting or tracking LPAI
   H5 or H7 detections in wild birds so states and universities tested
   wild bird samples independently of USDA. Because of this, the above
   list of previous detections might not be all inclusive of past LPAI
   H5N1 detections. However, the World Organization for Animal Health
   (OIE) recently changed its requirement of reporting detections of avian
   influenza. Effective in 2006, all confirmed LPAI H5 and H7 AI subtypes
   must be reported to the OIE because of their potential to mutate into
   highly pathogenic strains. Therefore, USDA now tracks these detections
   in wild birds, backyard flocks, commercial flocks and live bird
   markets."

Properties of H5N1

Infectivity

                        Highly pathogenic H5N1
   Highly pathogenic H5N1
    →  Countries with poultry or wild birds killed by H5N1.
    →  Countries with humans, poultry and wild birds killed by H5N1.

   H5N1 is easily transmissible between birds facilitating a potential
   global spread of H5N1. While H5N1 undergoes specific mutations and
   reassorting creating variations which infect species not previously
   known to carry the virus, not all of these variant forms can infect
   humans. H5N1 as an avian virus preferentially binds to a type of
   galactose receptors that populate the avian respiratory tract from the
   nose to the lungs and are virtually absent in humans, occurring only in
   and around the alveoli, structures deep in the lungs where oxygen is
   passed to the blood. Therefore, the virus is not easily expelled by
   coughing and sneezing, the usual route of transmission.

   H5N1 is mainly spread by domestic poultry, both through the movements
   of infected birds and poultry products and through the use of infected
   poultry manure as fertilizer or feed. Humans with H5N1 have typically
   caught it from chickens, which were in turn infected by other poultry
   or waterfowl. Migrating waterfowl (wild ducks, geese and swans) carry
   H5N1, often without themselves becoming sick. Many species of birds and
   mammals can be infected with HPAI A(H5N1), but the role of animals
   other than poultry and waterfowl as disease-spreading hosts is unknown.

Virulence

   H5N1 has mutated into a variety of strains with differing pathogenic
   profiles, some pathogenic to one species but not others, some
   pathogenic to multiple species. Each specific known genetic variation
   is traceable to a virus isolate of a specific case of infection.
   Through antigenic drift, H5N1 has mutated into dozens of highly
   pathogenic varieties divided into genetic clades which are known from
   specific isolates, but all currently belonging to genotype Z of avian
   influenza virus H5N1, now the dominant genotype. H5N1 isolates found in
   Hong Kong in 1997 and 2001 were not consistently transmitted
   efficiently among birds and did not cause significant disease in these
   animals. In 2002 new isolates of H5N1 were appearing within the bird
   population of Hong Kong. These new isolates caused acute disease,
   including severe neurological dysfunction and death in ducks. This was
   the first reported case of lethal influenza virus infection in wild
   aquatic birds since 1961. Genotype Z emerged in 2002 through
   reassortment from earlier highly pathogenic genotypes of H5N1 that
   first infected birds in China in 1996, and first infected humans in
   Hong Kong in 1997. Genotype Z is endemic in birds in Southeast Asia,
   has created at least two clades that can infect humans, and is
   spreading across the globe in bird populations. Mutations are occurring
   within this genotype that are increasing their pathogenicity. Birds are
   also able to shed the virus for longer periods of time before their
   death, increasing the transmissibility of the virus.

Transmission and host range

   Influenza A virus, the virus that causes Avian flu. Transmission
   electron micrograph of negatively stained virus particles in late
   passage. (Source: Dr. Erskine Palmer, Centers for Disease Control and
   Prevention Public Health Image Library)
   Enlarge
   Influenza A virus, the virus that causes Avian flu. Transmission
   electron micrograph of negatively stained virus particles in late
   passage. (Source: Dr. Erskine Palmer, Centers for Disease Control and
   Prevention Public Health Image Library)

   Infected birds transmit H5N1 through their saliva, nasal secretions,
   feces and blood. Other animals may become infected with the virus
   through direct contact with these bodily fluids or through contact with
   surfaces contaminated with them. H5N1 remains infectious after over 30
   days at 0 °C ( 32.0 °F) (over one month at freezing temperature) or 6
   days at 37 °C ( 98.6 °F) (one week at human body temperature) so at
   ordinary temperatures it lasts in the environment for weeks. In arctic
   temperatures, it doesn't degrade at all.

   Because migratory birds are among the carriers of the highly pathogenic
   H5N1 virus, it is spreading to all parts of the world. H5N1 is
   different from all previously known highly pathogenic avian flu viruses
   in its ability to be spread by animals other than poultry.

   In October 2004, researchers discovered that H5N1 is far more dangerous
   than was previously believed. Waterfowl were revealed to be directly
   spreading the highly pathogenic strain of H5N1 to chickens, crows,
   pigeons, and other birds, and the virus was increasing its ability to
   infect mammals as well. From this point on, avian flu experts
   increasingly referred to containment as a strategy that can delay, but
   not ultimately prevent, a future avian flu pandemic.

   "Since 1997, studies of influenza A (H5N1) indicate that these viruses
   continue to evolve, with changes in antigenicity and internal gene
   constellations; an expanded host range in avian species and the ability
   to infect felids; enhanced pathogenicity in experimentally infected
   mice and ferrets, in which they cause systemic infections; and
   increased environmental stability".

   The New York Times, in an article on transmission of H5N1 through
   smuggled birds, reports Wade Hagemeijer of Wetlands International
   stating, "We believe it is spread by both bird migration and trade, but
   that trade, particularly illegal trade, is more important".

High mutation rate

   Influenza viruses have a relatively high mutation rate that is
   characteristic of RNA viruses. The segmentation of the influenza genome
   facilitates genetic recombination by segment reassortment in hosts who
   are infected with two different influenza viruses at the same time.
   H5N1 viruses can reassort genes with other strains that co-infect a
   host organism, such as a pig, bird, or human, and mutate into a form
   that can pass easily among humans. This is one of many possible paths
   to a pandemic.

   The ability of various influenza strains to show species-selectivity is
   largely due to variation in the hemagglutinin genes. Genetic mutations
   in the hemagglutinin gene that cause single amino acid substitutions
   can significantly alter the ability of viral hemagglutinin proteins to
   bind to receptors on the surface of host cells. Such mutations in avian
   H5N1 viruses can change virus strains from being inefficient at
   infecting human cells to being as efficient in causing human infections
   as more common human influenza virus types. This doesn't mean that one
   amino acid substitution can cause a pandemic, but it does mean that one
   amino acid substitution can cause an avian flu virus that is not
   pathogenic in humans to become pathogenic in humans.

   H3N2 (" swine flu") is endemic in pigs in China, and has been detected
   in pigs in Vietnam, increasing fears of the emergence of new variant
   strains. The dominant strain of annual flu virus in January 2006 was
   H3N2, which is now resistant to the standard antiviral drugs amantadine
   and rimantadine. The possibility of H5N1 and H3N2 exchanging genes
   through reassortment is a major concern. If a reassortment in H5N1
   occurs, it might remain an H5N1 subtype, or it could shift subtypes, as
   H2N2 did when it evolved into the Hong Kong Flu strain of H3N2.

   Both the H2N2 and H3N2 pandemic strains contained avian flu virus RNA
   segments. "While the pandemic human influenza viruses of 1957 (H2N2)
   and 1968 (H3N2) clearly arose through reassortment between human and
   avian viruses, the influenza virus causing the 'Spanish flu' in 1918
   appears to be entirely derived from an avian source".

Humans and H5N1

   The earliest infections of humans by H5N1 coincided with an epizootic
   (an epidemic in nonhumans) of H5N1 influenza in Hong Kong's poultry
   population. This panzootic (a disease affecting animals of many
   species, especially over a wide area) outbreak was stopped by the
   killing of the entire domestic poultry population within the territory.

   CAPTION: Confirmed human cases and mortality rate of avian influenza
   (H5N1)
   As of November 13, 2006

   Country Report dates
   Total
   2003 2004 2005 2006
   cases deaths cases deaths cases deaths cases deaths cases deaths
   Flag of Azerbaijan  Azerbaijan   8 5 63% 8 5 63%
   Flag of Cambodia  Cambodia   4 4 100% 2 2 100% 6 6 100%
   People's Republic of China  People's Republic of China 1 1 100%   8 5
   63% 12 8 67% 21 14 67%
   Flag of Djibouti  Djibouti   1 0 0% 1 0 0%
   Flag of Egypt  Egypt   15 7 47% 15 7 47%
   Flag of Indonesia  Indonesia   19 12 63% 55 44 80% 74 56 76%
   Flag of Iraq  Iraq   3 2 67% 3 2 67%
   Flag of Thailand  Thailand   17 12 71% 5 2 40% 3 3 100% 25 17 68%
   Flag of Turkey  Turkey   12 4 33% 12 4 33%
   Flag of Vietnam  Vietnam 3 3 100% 29 20 69% 61 19 31%   93 42 45%
   Total 4 4 100% 46 32 70% 97 42 43% 111 75 68% 258 153 59%
   Source World Health Organization (WHO) :
   Communicable Disease Surveillance & Response (CSR).

Symptoms in humans

   Avian influenza hemagglutinin bind alpha 2-3 sialic acid receptors
   while human influenza hemagglutinin bind alpha 2-6 sialic acid
   receptors. Usually other differences also exist. There is as yet no
   human form of H5N1, so all humans who have caught it so far have caught
   avian H5N1.

   Humans who catch a humanized Influenza A virus (in other words a human
   flu virus of type A) usually have symptoms that include fever, cough,
   sore throat, muscle aches, conjunctivitis and, in severe cases, severe
   breathing problems and pneumonia that may be fatal. The severity of the
   infection will depend to a large part on the state of the infected
   person's immune system and if the victim has been exposed to the strain
   before, and is therefore partially immune. No one knows if these or
   other symptoms will be the symptoms of a humanized H5N1 flu.

   Highly pathogenic H5N1 avian flu in a human is far worse, killing 50%
   of humans that catch it. In one case, a boy with H5N1 experienced
   diarrhea followed rapidly by a coma without developing respiratory or
   flu-like symptoms. There have been studies of the levels of cytokines
   in humans infected by the H5N1 flu virus. Of particular concern is
   elevated levels of tumor necrosis factor alpha, a protein that is
   associated with tissue destruction at sites of infection and increased
   production of other cytokines. Flu virus-induced increases in the level
   of cytokines is also associated with flu symptoms including fever,
   chills, vomiting and headache. Tissue damage associated with pathogenic
   flu virus infection can ultimately result in death. The inflammatory
   cascade triggered by H5N1 has been called a ' cytokine storm' by some,
   because of what seems to be a positive feedback process of damage to
   the body resulting from immune system stimulation. H5N1 induces higher
   levels of cytokines than the more common flu virus types.

Treatment and prevention for humans

   CAPTION: Flu

     * Flu
     * Flu season
     * Flu vaccine
     * Flu treatment
     * Avian flu
     * H5N1 flu
     * Flu research
     * Genome sequencing

   There is no highly effective treatment for H5N1 flu, but oseltamivir
   (commercially marketed by Roche as Tamiflu), can sometimes inhibit the
   influenza virus from spreading inside the user's body. This drug has
   become a focus for some governments and organizations trying to be seen
   as making preparations for a possible H5N1 pandemic. On April 20, 2006,
   Roche AG announced that a stockpile of three million treatment courses
   of Tamiflu is waiting at the disposal of the World Health Organization
   to be used in case of a flu pandemic; separately Roche donated two
   million courses to the WHO for use in developing nations that may be
   affected by such a pandemic but lack the ability to purchase large
   quantities of the drug.

   However, WHO expert Hassan al-Bushra has said:

          "Even now, we remain unsure about Tamiflu's real effectiveness.
          As for a vaccine, work cannot start on it until the emergence of
          a new virus, and we predict it would take six to nine months to
          develop it. For the moment, we cannot by any means count on a
          potential vaccine to prevent the spread of a contagious
          influenza virus, whose various precedents in the past 90 years
          have been highly pathogenic".

   There are several H5N1 vaccines for several of the avian H5N1
   varieties, but the continual mutation of H5N1 renders them of limited
   use to date: while vaccines can sometimes provide cross-protection
   against related flu strains, the best protection would be from a
   vaccine specifically produced for any future pandemic flu virus strain.
   Dr. Daniel Lucey, co-director of the Biohazardous Threats and Emerging
   Diseases graduate program at Georgetown University has made this point,
   "There is no H5N1 pandemic so there can be no pandemic vaccine".
   However, "pre-pandemic vaccines" have been created; are being refined
   and tested; and do have some promise both in furthering research and
   preparedness for the next pandemic. Vaccine manufacturing companies are
   being encouraged to increase capacity so that if a pandemic vaccine is
   needed, facilities will be available for rapid production of large
   amounts of a vaccine specific to a new pandemic strain.

   Animal and lab studies suggest that Relenza ( Zanamivir), which is in
   the same class of drugs as Tamiflu, may also be effective against H5N1,
   in a study performed on mice in 2000, "zanamivir was shown to be
   efficacious in treating avian influenza viruses H9N2, H6N1, and H5N1
   transmissible to mammals" (Leneva 2001). However another paper, de Jong
   2005, suggested that Zazamivir might not provide protection in humans
   from the current avian strain of H5N1 if "systemic involvement of
   influenza infection is suspected - as has recently been suggested by
   some reports on avian H5N1 influenza in humans." While no one knows if
   zanamivir will be useful or not on a yet to exist pandemic strain of
   H5N1, it might be useful to stockpile zanamivir as well as oseltamivir
   in the event of an H5N1 influenza pandemic. Neither oseltamivir nor
   zanamivir can currently be manufactured in quantities that would be
   meaningful once efficient human transmission starts.

   In September, 2006, a WHO scientist announced that studies had
   confirmed cases of strains resistant to Tamiflu and Amantadine.

Preparations for pandemic

   CAPTION: Cumulate Human Cases of and Deaths from H5N1
   As of November 13, 2006

   Image:H5n1 spread (with regression).png

   Notes:
     * Source WHO Confirmed Human Cases of H5N1
     * "[T]he incidence of human cases peaked, in each of the three years
       in which cases have occurred, during the period roughly
       corresponding to winter and spring in the northern hemisphere. If
       this pattern continues, an upsurge in cases could be anticipated
       starting in late 2006 or early 2007." Avian influenza –
       epidemiology of human H5N1 cases reported to WHO
     * The regression curve for deaths is y = a + e^k x, and is shown
       extended through the end of November, 2006.

   "The United States is collaborating closely with eight international
   organizations, including the World Health Organization (WHO), the Food
   and Agriculture Organization of the United Nations (FAO), the World
   Organization for Animal Health (OIE), and 88 foreign governments to
   address the situation through planning, greater monitoring, and full
   transparency in reporting and investigating avian influenza
   occurrences. The United States and these international partners have
   led global efforts to encourage countries to heighten surveillance for
   outbreaks in poultry and significant numbers of deaths in migratory
   birds and to rapidly introduce containment measures. The U.S. Agency
   for International Development (USAID) and the U.S. Department of State,
   the U.S. Department of Health and Human Services (HHS), and Agriculture
   (USDA) are coordinating future international response measures on
   behalf of the White House with departments and agencies across the
   federal government".

   Together steps are being taken to "minimize the risk of further spread
   in animal populations", "reduce the risk of human infections", and
   "further support pandemic planning and preparedness".

   Ongoing detailed mutually coordinated onsite surveillance and analysis
   of human and animal H5N1 avian flu outbreaks are being conducted and
   reported by the USGS National Wildlife Health Centre, the Centers for
   Disease Control and Prevention, the World Health Organization, the
   European Commission, and others.

Impact on human society

   There has been a huge impact of H5N1 on human society; especially the
   financial, political, social and personal responses to both actual and
   predicted deaths in birds, humans, and other animals.

   Billions of U.S. dollars are being raised and spent to research H5N1
   and prepare for a potential avian flu pandemic. Over ten billion
   dollars have been lost and over two hundred million birds have been
   killed to try to contain H5N1.

   This, like everything else, is subject to political spin; wherein every
   interest group picks and chooses among the facts to support their
   favorite cause resulting in a distortion of the overall picture, the
   motivations of the people involved and the believability of the
   predictions.

   People have reacted by buying less chicken causing poultry sales and
   prices to fall. Many individuals have stockpiled supplies for a
   possible flu pandemic. One of the best known experts on H5N1, Dr.
   Robert Webster, told ABC News he had a three month supply of food and
   water in his house as he prepared for what he considered a reasonably
   likely occurrence of a major pandemic.

   Retrieved from " http://en.wikipedia.org/wiki/H5N1"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
