Viral arthritis (poultry)

Viral arthritis in poultry is a common disease primarily affecting broiler chickens, turkeys, and ducks, causing inflammation of the joints and tendon sheaths. It's often associated with significant economic losses in the poultry industry due to reduced growth rates, carcass downgrading at processing, and increased mortality.

Etiology:

The primary causative agent of viral arthritis is reovirus, specifically avian reoviruses. Different strains of reovirus exhibit varying levels of virulence. Other viruses, such as some strains of avian adenoviruses, can also contribute to or exacerbate the condition.

Transmission:

Reovirus is highly contagious and can spread both vertically (from parent to offspring via the egg) and horizontally (through direct contact with infected birds, contaminated litter, water, or feed, and mechanical vectors like equipment or personnel).

Clinical Signs:

Affected birds typically exhibit lameness, reluctance to move, swelling of the hock joints and footpads, and, in severe cases, rupture of the gastrocnemius tendon. Birds may appear depressed, have ruffled feathers, and exhibit poor growth.

Diagnosis:

Diagnosis is typically based on a combination of clinical signs, gross lesions observed during necropsy (post-mortem examination), and laboratory testing. Laboratory tests may include virus isolation, polymerase chain reaction (PCR) to detect viral nucleic acid, and serological assays (e.g., ELISA) to detect antibodies to reovirus. Histopathology of affected joints and tendon sheaths can also be helpful.

Treatment:

There is no specific antiviral treatment for viral arthritis. Treatment focuses on supportive care, such as providing clean and comfortable housing, ensuring adequate access to feed and water, and controlling secondary bacterial infections with antibiotics when necessary.

Prevention and Control:

Prevention is the most effective strategy. Key measures include:

• Biosecurity: Strict biosecurity practices are essential to prevent the introduction and spread of the virus. This includes controlling access to poultry houses, disinfecting equipment, and implementing proper sanitation protocols.
• Vaccination: Vaccination of breeder flocks is a crucial tool for controlling vertical transmission and providing passive immunity to offspring. Broiler chickens can also be vaccinated, though the timing and efficacy depend on the specific vaccine and strain of reovirus involved.
• Genetic Resistance: Selecting for birds with increased genetic resistance to reovirus infection can also contribute to long-term control.
• Sanitation: Thorough cleaning and disinfection of poultry houses between flocks are essential to reduce viral load.
• Proper Management: Providing optimal environmental conditions and nutrition can help improve the overall health and immune status of birds, making them less susceptible to infection.