Avian influenza ( Bird flu )

Introduction Avian influenza or “ Bird Flu ” , the disease Which Was first identified in Italy more than 100 years ago . Is a contagious disease of animals caused by viruses that normally infect only birds and , less commonly ,pigs . While all bird species are thought to be susceptible to infection , domestic poultry flocks are especially vulnerable to infections that can rapidly reach epidemic proportions .

What is A I Caused by avian iflu virus which occur naturally in birds. Wild animals carry virus in their intestine but usually do not get sick from it. Very contagious among birds and can make some domestic birds (chickens, ducks and turkeys) very sick and kill them

Do A I VIRUSES INFECT HUMANS They do not usually infect humans, but more than 100 cases of human infection have occurred since 1997.

Types of influenza virus Three types: A, B, C Type A : Can infect people, birds, pigs, horses , whales and others Type B :* human virus * Not classified according to subtype * Cause human epidemics but not pandemic. TYPE C: cause mild illness in humans.

How are AI viruses (H5N1) different from human flu viruses There are different subtypes of type A IV. Certain protein on the surface of the virus: ( HA) hemagglutinine-- (NA) neuraminidase There are 16 different HA and 9 different NA subtypes Many different combinations HA and NA are possible , all known subtypes can be found in birds. There are only three known A subtypes of human AI H1N1, H1N2, H3N2. IV are constantly changing

H5N1 The most subtype which make concern: *Mutates rapidly. *has a documented propensity to acquire genes from virus infecting other animals. *Have high pathogenicity and can cause severe disease in humans . *Infected birds excrete virus for at least 10 days orally and in faeces, facilitating further spread at live poultry markets and by migratory birds.

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Hgs in the pericardium

Cont Preservation measures such as freezing and refrigeration will not reduce the concentration or kill the virus, so frozen poultry should be handled with the same precautions. Eggs may contain virus both on the outside (shell) and inside (white and yolk), eggs should be properly cooked (no runny yolks).

Diagnosis Individuals infected With H5 N1 are considered to be infectious starting from one day prior to the onset of symptoms up to seven days after the onset of symptoms . The cases of the human influenza A ( H5N1) Can be classified into :

Possible case : which is a person with acute lower respiratory tract illness of ale nupt onset of : fever> 38 , sore throat , cough , dyspnea +one or more of : - Contact within prior 7 days with a confirmed case of influenza A ( H5N1) - Recent ( within prior 7 days) visit to a poultry farm known to have out breaks or endemic for HPAI - Recent (within prior 7 days) contact with birds that were unwell or that have died of an illness. -Having worked in a laboratory (within prior 7 days) that is processing samples from persons or animals that are suspected of HPAI infection .

* Probable case : It is a possible case and Limited laboratory evidence for influenza A ( H5N1) Such as IFA test +ve Using H2 monoclonal antibodies )

Confirmed case : An individual for whom laboratory testing demonstrates One or more of the following : A) Positive Viral culture for influenza A ( H5N1) . OR B) Positive PCR for influenza A( H5N1) . OR c) Immunofluorescence antibody ( IFA) test positive using influenza A /H5 monoclonal antibodies. OR D) A four – fold rise in H5 specific Ab titre .

WHO teams in Vietnam and Thailand are conducting studies to detect the earliest stage of human transmission , and a new virus adopted for efficient human to human transmission Would spread very rapidly due to the emerge of a completely new virus . To date , this has never occurred .

Vaccine against H5N1 In human Currently available vaccines will not protect against disease caused by the H5N1strain in humans . - An available vaccine prototype virus , developed using the 2003 strain of H5N1 ( which caused the two human cases in Hong Kong ) cannot be used now because the laboratory analysis indicates that the virus has mutated significantly .

Annual vaccines are produced for routine use in protecting humans during seasonal epidemics of influenza , they offer no protection against infection with the H5N1 avian virus . The experience in the production of influenza vaccines is also considerable . However , at least four months would be needed to produce a new vaccine , in significant quantities , capable of conferring protection against a new virus subtype .

Drugs used in prevention and treatment There are two classes of drugs available Now 1) M2 inhibitors : - Amantadine (Adamine). - Rimantadine 2) Neuraminidase inhibitors: -Oseltamivir ( Tami flu ) - Zanimivir

ADAMINE Treatment : = Amantadine Hydrochloride 100 mg Capsule oral capsules for treatment and prophylaxis of Respiratory tract against influenza A virus it is not a replacement of influenza vaccines Treatment : * Adult 2 Capsules ( 200 mg ) / day OR 1 capsule 2 / day For 5-7 days * Old age ( above 65 years ) 1 Capsule ( 100 mg ) / day .

Prophylaxis - Not used as a prophylaxis against influenza in children . - treatment dose is used as a prophylaxis in : . All the period of epidemic ( 5-6 weeks ) OR. In addition with vaccine ( 1-2 weeks ) - application of infection control rules .

( OSELTAMIVIR PHOSPHATE ) TAMIFLU ( OSELTAMIVIR PHOSPHATE ) CAPSULES 75 mg oral use Powder for oral use Treatment : TAMIFLU is indicated for the treatment of uncomplicated acute illness due to influenza infection in patients 1 year and older who have been symptomatic for no more than 2 days .

Prophylaxis of influenza : TAMIFLU is indicated for the prophylaxis of influenza in adult patients and adolescents 13 years and older . Is not a substitute for early vaccination

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