Avian Reovirus

Dr. Naeem TahirAssistant Manager Sales Jadeed Farms (Pvt) ltd.Faisalabad

Introduction In 1957, Olson and his coworkers determined that the synovitis agent was a virus, which they called “viral arthritis agent.” The virus was subsequently identified by Walker as a reovirus by electron microscopy. Soon other isolations of reovirus were reported from various places in the United States and all around the world.

Cases of Reovirus tenosynovitis have been reported throughout the UK in a number of integrations this year.

Cases of Reovirus tenosynovitis have been reported throughout Europe and

United States of America and many other Asian and African countries throughout the last year.

Occurrence

Virus isolation Aseptically extracted tendon

tissue from broilers Virus isolation conducted by

AHVLA Weybridge 3 Passages Reovirus isolated

FROM TENODON TISSUE

Histology Tendons, joint capsule and tendon

sheath- mixed inflammatory infiltrate- both heterophilic and lymphoplasmacytic.

NOT POSSIBLE TO DETERMINE WHETHER BACTERIAL OR VIRAL FROM HISTOLOGY ALONE.

General Characteristics Birds reported lame “walking on their hocks using wings to balance”.

Acute onset at 13-14 days of age.

Poor uniformity

Poor growth rates

Bursa of Fabricius and thymus gland are atrophied.

Femoral head disintegration on disarticulation of the coxofemoral joint.

Thickening of the growth plates of long bones.

Arthritis and osteoporosis.

Transmission Through infected and carrier birds Poultry products, offal's from infected birds Mechanical vectors Wild birds Faulty vaccination Contaminated feed and water Vertical route of transmission is also proved

Thymus cortex is thinner and difficult to be differentiated from medulla.

Atrophy of follicles of Bursa of Fabricius.

Bones abnormality in the femur growth plate with necrosis of cartilage.

Proventriculitis with focal necrosis and infiltration of Inter glandular tissue with mononuclear cells.

Histopathological lesions

Distended abdomen Increased fluid in tendons of hocks Concurrent mild pericarditis/epicarditis Enlarged proventriculus Shrinkin pancreas Intestine containing undigested orange feed

Postmortem examination

Differential diagnosis

Primarily considered likely infectious agent given inflammation and effusion of tendonMycoplasma Synoviae

Staphylococcus Tenosynovitis/ Arthritis

Enterococcus Tenosynovitis/Arthritis

Airsacculitis

Inflammation of joints

Ruffle feather

Distended abdomen

Shrinkin pancreas

Reovirus Nil Yes Yes yes Yes

Mycoplasma Synoviae

Yes In some cases

Yes Nil Nil

Staphylococcus Tenosynovitis/ Arthritis

Nil Yes Yes Nil Nil

Enterococcus Tenosynovitis/Arthritis

Nil Yes Yes Nil Nil

1- Staphylococcus Tenosynovitis / Arthritis Swabs taken from hocks, tendons and pericardial tissuesResults – no growth after 48 hoursBirds swabbed not being treated with antibiotics and investigation undertaken at early stage of infection

NOT STAPHYLOCOCCUS OR ENTEROCOCCUS TENOSYNOVITIS/ARTHRITIS

Course of investigation

2- Mycoplasma SynoviaeSerology:Rapid serum agglutination on sera of 20 birds showing symptoms in affected flock- taken at time of site visitResults- negativeHowever- serology relies on antibody production- acute vs convalescent phase of infection- could not rule out on the basis of this test alone

Then……..8-12% mortality due to cullingNo response to antibiotic treatment either

antimycoplasmal or amoxycillinWelfare concerns due to lameness Poor conversion 1.80+ vs 1.62Poor uniformitySome response to aspirin treatment-

– better mobility, lower culling rates

Questions! Why have so many companies and countries suddenly reported this syndrome?

Why have some flocks which have not been derived from the known positive PS also developed symptoms?- cross infection in hatchery?

Why did some flocks from the same parent flock not show symptoms?- age related resistance?

Is this a new strain of Reovirus or is it a previously recognised strain?- Reoviruses appear to be continuously involving.

What methods are being used to type Reovirus and are these consistent throughout laboratories?- there is no consistency at this time.

Will double Reo inactive vaccination confirms protection?

• Biosecurity• Hatching egg hygiene• Hatchery hygiene• Vaccination- double vaccination

strategy advised in outbreak areas• Sigma B antibodies• Autogenous vaccination

Prevention and Control

General appearance of the effected bird

Swelling of hock joint

Diagrams of Post mortem Lesions of Avian Reovirus

Enlarged Proventiculus

Distended abdomen

Tissue fibrosis in the affected area

Tendon sheaths contain a small amount of straw-yellow exudates

Intestine containing undigested orange

feed

Catarrhal enteritis with white color and Dilated

intestine.

Shrinkin pancreas in affected broiler

Shrinkin pancreas in affected broiler

Small intestine is pale, dilated and contain indigested forage

Small intestine is pale and dilated

Thank you