BAR TODAY || Official Quarterly Publication of the Bureau of Agricultural Research

Archives (2003) : Livestock & Poultry

Screening Viral arthritis in chicken
by Rita dela Cruz

January-March 2003
Volume 5 No. 1

Arthritis is not only common to humans, it's also prevalent in chicken. In fact, it is one of the many viral diseases common in poultry production. Viral arthritis (VA) also known as "tenosynovitis" or "reovirus infection" ischaracterized by swelling and stiffening of joints in chicken and is caused by viral infection.

Chicken part infected with reovirus
Photos from www.poultrymed.com

Viral arthritis (VA) also known as "tenosynovitis" or "reovirus infection" is characterized by swelling and stiffening of joints in chicken and is caused by viral infection.

Drs. Ma. Suzanneth Lola, Calcita Morales, and Rosemarie ntegro of the Bureau of Animal Industry (BAI), were able to develop a reovirus antigen that could detect viral arthritis agent in chickens.

The disease is attributed to reovirus strain WVU 2939. Reovirus is a virus that contains double-stranded RNA and is associated with various diseases such as pericarditis, hydropericardium, pasting, malabsorption and femoral headnecrosis. It is usually found in meat-type chickens particularly those between 4 to 8 weeks of age.

VA is marked by inflammations of both the flexor and the lower part of the leg (extensor tendons) causing lameness and thereby restricting body movements. The diseased portion is manifested by the swelled tendon, which is easily examined in one or both legs.

When the infection becomes chronic, tendonitis persists and could lead to the rupture of gastrocnemius muscle. Meanwhile, in mild cases, swelling only affects the flexor tendons of the chicken causing no severe pains and limping.

The mortality rate of chickens infected with VA is under 1% but it may increase to 10% because of the lack of effective means to screen and monitor this kind of infection.

The incidence of the disease varies according to areas affected. Outbreaks occur when the synovitis (a clear viscous fluid that lubricates the linings of joints and the sheaths of tendons in chickens) is damaged.

Dr. Ma. Suzanneth Lola, Dr. Calcita Morales, and Dr. Rosemarie Antegro of the Bureau of Animal Industry (BAI), were able to develop a reovirus antigen that could detect viral arthritis agent in chickens. An antigen is a substance, usually protein, on the surface of a cell or bacterium that stimulates the production of antibody. Having assessed the value of this screen tool, the group studied its efficacy through Agar Gel Precipitation Test (AGPT). The efficacy of the AGPT was determined using two important factors: the sensitivity of the test in giving positive result to the diseased animal and the specificity to give a negative result to a healthy animal.

To determine if the reovirus antigen is effective in terms of the sensitivity and specificity parameters, the researchers used three farms each having six chickens as samples. A total of 24 serum samples was collected and evaluated using AGPT. Serum is the fluid that separates from clotted blood, similar to plasma but without clotting agents. The result of the tests gave 100 % specificity and 100% sensitivity to AGPT. Thus, the field test showed that the reovirus antigen developed by BAI proved to be effective as screening diagnostic tool for VA.

This technology is part of BAI's disease diagnosis and surveillance program and greatly contributes to the local poultry industry. Moreover, since the cost of production is low and the availability of materials is immediate, the reovirus antigen aside from its proven efficacy is practical and economical. It was found that a milliliter (ml) of the prepared antigen could be used for 60 tests.

This technology was one of the R&D paper entries during the 14th National Research Symposium, which is being annually coordinated and facilitated by the Department of Agriculture (DA) through the Bureau of Agricultural Research (BAR). It won the AFMA Best R&D Paper Award under the Animal and Veterinary Science-downstream category.

For more information about the reovirus antigen, please contact Ma. Suzanneth G. Lola, Calcita M. Morales, and Rosemarie N. Antegro at Philippine Animal Health Center of the Bureau Animal Industry (PAHC-BAI) or you may call them through these numbers: 927-0971, 926-6883 or fax at 920-0429.