LanguageReoviruses were first recognised as avian pathogens in 1957. This first case was from chickens showing clinical signs of what became known as viral arthritis (VA). Since that time reoviruses have become associated with other disease conditions including malabsorption syndrome (MAS), femoral head necrosis (FHN), pericarditis, myocarditis, hydropericardium, gastroenteritis, hepatitis, and acute and chronic respiratory syndromes.
Reovirus infections (REO) are prevalent in chickens, turkeys and other avian species worldwide. The virus is transmitted vertically via the hatching egg and horizontally by faeces and the respiratory systems. The virus is commonly found in the digestive and respiratory tracts of clinically healthy birds.
Chickens in the first week of life are most susceptible to REO infections. In meat-type chickens and turkeys, the virus can cause malabsorption syndrome with symptoms such as runting stunting, poor pigmentation, abnormal feathering, skeletal abnormalities, increased mortality and an enlarged proventiculus.
- Ruptured tendon
Viral arthritis/ tenosynovitis with joint swelling, thickened or ruptured tendons and lameness are commonly observed clinical signs of a REO infection.
Leg problems and malabsorption syndrome in young birds justify all the concern poultry producers have put on Reovirus as a potential cause for economical losses. Because chicks are most susceptible to REO infections during the first week of life, protection by maternal antibodies is an obvious road to control. The best way to do this is to induce high and uniform levels of immunity in the parent flocks, by vaccinating the parent flocks with an inactivated REO vaccine. Live vaccines are mainly used as primers, to increase the booster effect of the killed vaccine.