AVIAN INFLUENZA

                  –     It is a viral influenza of birds including chickens turkeys and more

• Symptoms vary in severity from asymptomatic infection to mild  respiratory and reproductive disease
• Distributed worldwide and are recovered frequently from shorebirds and waterfowl
• Virus may be present in village or backyard flocks
• Young flattening turkeys and laying hens are most affected

   ETIOLOGY:

• AI virus are -ve sense ,ss RNA virus in family orthomyxoviridae
• Genius : Influenza A(zoonotic)
• Further classified into : Hemagglutinin (H1- 16|)

                                   Neuraminidase N(1-9) subtypes

TYPES

• Low pathogenicity AI (LPAI) : by H1-4 ,h6 ,h8-10
• Low pathogenicity notifiable AI (LPNAI) : only by h5 and h7
• Highly pathogenicity or highly pathogenic notifiable AI   (HPNAI)  : only by mutated forms of h5 and h7

TRANSMISSION

• IPis highly variable and ranges from a few days in individual birds to 2 week in flock

Sources of virus

a. Major :

• Infected poultry and live bird markets
• Faces secretion
• Infected water fowl

b. Minor :

• Uncooked infected poultry product h1/h3 swine to tourkeys
• Pet birds

ROUTES OF TRANSMISSION

• Oral ➦ faces / cannibalism
• Aerosol
• Families : people, equipment, vehicles,  feed and water, rodents , sparrow , winds , etc

PATHOGENESIS

• Exhibits severe lethargy ,fever Wt loss , transient lymphopenia and replication in upper and lower respiratory tract as well as multiple systemic organs , including brain .

CLINICAL FINDING AND LESIONS

• Clinical sign severity of disease and mortality

rates vary depending on Ai virus strain and host species

1. 1. Low pathogenicity AI virus:-

• Respiratory signs as:
• Sneezing coughing
• Ocular and nasal discharge
• Swollen infraorbital sinuses
• Sinusitis is common

• lesions in respiratory tract includes congestion
• In layer and breeders
• Decreased egg production or fertility
• Acute renal failure
• Visceral urate disposition
• Mortality and morbidity is usually low

2. high pathogenicity AI virus

• Severe systemic disease with high mortality in chickens

• In peracute cases : lack of sign or grass lesion before death
• In acute cases: cyanosis and edema of head, comb and wattle and snood ( turkey)
• Blood-tinged oral and nasal discharges
• Edema and haemorrhages lesions and shanks feed and comb

• In severe cases

 –   greenish diarrhoea is common

–    birds that survive the peracute infection may develop cns involved evident as;

• Torticollis
• Opisthotonus
• incoordination
• paralysis
• drooping wing

Fig :comb and wattle are congested and  marked edematous       

fig : shanks are swollen and extensively haemorrhages

Fig : there are numerous epicardial petechiae  

Fig : multiple hemorrhages on mucosal  surface of proventriculus                  

fig : serosal haemorrhages on the Peyer’s patches

MIcroscopic lesions

• Highly variable and may consist of edema , hemorrhage and necrosis in parenchymal cells of multiple visceral organs , skin and CNS 
• Subcutaneous ecchymotic hemorrhages : Petechial hemorrhages  on visceral organ and in muscles

DIAGNOSIS:-

• LPAI and HPAIvirus can be readily isolated from oropharyngeal and cloacal swabs

            AI viruses grow well in the allantoic sac of 9-11 days old embryonated chicken eggs, and they agglutinate RBCs .

• PCR (diagnostic test)
• Detection of AI virus RNA
• Detection of AI specific Antibody
• Serological ( AGID or ELISA )

DDX

1)LPAI :-  differentiated from other respiratory disease  or causes of decreased egg production including :

1. Acute to subacute viral disease ;

• Infectious bronchitis
• Infectious laryngotracheitis
• Low virulent ND
• Infection by other paramyxoviruses

1. Bacterial disease  ; mycoplasmosis , infectious coryza , fowl cholera (resp. form)
2. Fungal disease : aspergillosis

2)HPAI :-

• High mortality such as
• virulent ND
• Peracute septicaemic form of fowl cholera
• Heat exhaustion
• Severe water deprivation