Avian InfluenzaAvian Influenza

H5N1H5N1

Prepared by:

Samia ALhabardi

IntroductionIntroduction::

What is avian influenza What is avian influenza ((bird bird flu)flu)??

Bird flu is an infection caused by Bird flu is an infection caused by avian avian ((birdbird) ) influenza influenza ((fluflu) ) virusesviruses. . These flu viruses occur These flu viruses occur naturally among birdsnaturally among birds. . Wild Wild birds worldwide carry the birds worldwide carry the viruses in their intestines, but viruses in their intestines, but usually do not get sick from usually do not get sick from themthem. . However, bird flu is very However, bird flu is very contagious among birds and contagious among birds and can make some domesticated can make some domesticated birds, including chickens, ducks, birds, including chickens, ducks, and turkeys, very sick and kill and turkeys, very sick and kill themthem

Types, Subtypes, and StrainsTypes, Subtypes, and Strains

There are three types of influenza virusesThere are three types of influenza viruses: : A, B, and CA, B, and C..

Influenza Type AInfluenza type A viruses can infect people, birds, pigs, horses,, and other animals, but wild birds are the natural hosts for these viruses. Influenza type A viruses are divided into subtypes based on two proteins on the surface of the virus. These proteins are called hemagglutinin (HA) and neuraminidase (NA). There are 15 different HA subtypes and 9 different NA subtypes. Many different combinations of HA and NA proteins are possible. Only some influenza A subtypes (i.e., H1N1, H1N2, and H3N2) are currently in general circulation among people. Other subtypes are found most

commonly in other animal species..

Influenza Type BInfluenza B viruses are normally found only in humans. Unlike influenza A viruses, these viruses are not classified according to subtype. Although influenza type B viruses can cause human epidemics, they have not caused pandemics

Influenza Type CInfluenza type C viruses cause mild illness in humans and do not cause epidemics or pandemics. These viruses are not classified according to subtype.

StrainsInfluenza B viruses and subtypes of influenza A virus are further characterized into strains. There are many different strains of influenza B viruses and of influenza A subtypes. New strains of influenza viruses appear and replace older strains. This process occurs through a type of change is called “drift” (see How Influenza Viruses Can Change: Shift and Drift). When a new strain of human influenza virus emerges, antibody protection that may have developed after infection or vaccination with an older strain may not provide protection against the new strain. Thus, the influenza vaccine is updated on a yearly basis to keep up with the changes in influenza viruses

Symptoms of Avian Influenza in Symptoms of Avian Influenza in HumansHumans

The reported symptoms of avian influenza in The reported symptoms of avian influenza in humans have ranged from typical influenzahumans have ranged from typical influenza--like symptoms like symptoms ((ee..gg.., fever, cough, sore , fever, cough, sore throat, and muscle achesthroat, and muscle aches) ) to eye infections to eye infections ((conjunctivitisconjunctivitis)), pneumonia, acute , pneumonia, acute respiratory distress, viral pneumonia, and respiratory distress, viral pneumonia, and other severe and lifeother severe and life--threatening threatening complicationscomplications

Global spread 2004/2005Global spread 2004/2005

H5N1 StructureH5N1 Structure

MICROSCOPIC EXAMENATIONMICROSCOPIC EXAMENATION

Influenza A virus, the Influenza A virus, the virus that causes virus that causes Avian flu. Avian flu. Transmission Transmission electron micrograph electron micrograph of negatively stained of negatively stained virus particles in late virus particles in late

passagepassage , ,

Transmission of Influenza A Viruses Transmission of Influenza A Viruses Between Animals and PeopleBetween Animals and People

Avian influenza A viruses Avian influenza A viruses may be transmitted from may be transmitted from animals to humans in two animals to humans in two

main waysmain ways : :

Directly from birds or from Directly from birds or from avian virusavian virus--contaminated contaminated

environments to peopleenvironments to people . .

Through an intermediate Through an intermediate host, such as a pighost, such as a pig..

Laboratory Testing ProceduresLaboratory Testing Procedures Highly pathogenic avian influenza A Highly pathogenic avian influenza A ((H5N1H5N1) ) is classified as a select agent is classified as a select agent and must be worked with under Biosafety Level and must be worked with under Biosafety Level ((BSLBSL) ) 3+ laboratory 3+ laboratory conditionsconditions

CDC does not recommend that virus isolation studies on respiratory specimens from patients. Therefore, respiratory virus cultures should not be performed in most clinical laboratories and such cultures should not be ordered for patients suspected of having H5N1 infection .

Specimens from persons should be sent to CDC if The specimen tests positive for influenza A by PCR or by antigen detection testing, OR PCR assays for influenza are not available at the state public health laboratory .

Atypical Avian Influenza Atypical Avian Influenza ((H5N1H5N1

AA) ) Chest radiograph on Chest radiograph on hospital day 5 at referring hospital day 5 at referring hospital shows patchy hospital shows patchy infiltration at bilateral lower infiltration at bilateral lower lung fieldslung fields. . BB) ) Chest Chest radiograph upon radiograph upon admission to our hospital admission to our hospital ((24 hours later24 hours later) ) shows shows rapidly progressive rapidly progressive pneumonia in both lung pneumonia in both lung fields, compatible with fields, compatible with adult respiratory distress adult respiratory distress syndromesyndrome

Antiviral Agents for InfluenzaAntiviral Agents for Influenza Four different influenza antiviral drugs Four different influenza antiviral drugs ((amantadine, rimantadine, oseltamivir, amantadine, rimantadine, oseltamivir, and zanamivirand zanamivir) ) are approved by the Uare approved by the U..SS. . Food and Drug Administration Food and Drug Administration ((FDAFDA) ) for for the treatment of influenza; three are the treatment of influenza; three are approved for prophylaxisapproved for prophylaxis. . All four have All four have activity against influenza A virusesactivity against influenza A viruses. . However, sometimes influenza strains However, sometimes influenza strains can become resistant to these drugs, can become resistant to these drugs, and therefore the drugs may not always and therefore the drugs may not always be effectivebe effective. . For example, analyses of For example, analyses of some of the 2004 H5N1 viruses isolated some of the 2004 H5N1 viruses isolated from poultry and humans in Asia have from poultry and humans in Asia have shown that the viruses are resistant to shown that the viruses are resistant to two of the medications two of the medications ((amantadine and amantadine and

rimantadinerimantadine))....

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