Novel Reovirus in Meat Ducks

Avian reovirus Avian reovirus (ARV) Belongs to the Reoviridae family and the Orthoreovirus genus. 。 The viral particles are spherical in shape, with a diameter of 60–80 nm in size, with icosahedral symmetry and lacking a lipid envelope, the virus exhibits a distinct double-layered capsid structure under electron microscopy. Its genetic material consists of double-stranded RNA. Notably, the virus is resistant to treatment with ether, chloroform, or trypsin, as well as to incubation at 50°C for 1 hour or exposure to 3% formaldehyde for 30 minutes—demonstrating a remarkable ability to withstand environmental challenges.   [ [Popular Features]

This disease commonly occurs in Cherry Valley, Z Ducklings of the Muscovy breed and other varieties often occur in 5 to 7 Age at onset, incidence rate 60% to 90% This disease can spread both horizontally and vertically through hatching eggs, and it occurs without a clear seasonal pattern—outbreaks can happen year-round. Sudden changes in weather, poor farming conditions, and inadequate hygiene practices can easily trigger the onset of the disease.

[Clinical and Necropsy Findings]

The disease typically manifests at an age of 5 to 7 d. The mortality rate ranges from 10% to 15%, and in some infected duck flocks, deaths can persist beyond 30 days of age. Clinically, the early stage of infection primarily manifests as The spleen turns black, its size changes, and its texture becomes hard and brittle, developing irregular white or reddish-white necrotic areas. Death Points and necrotic foci. Later-stage ducks tended to be lighter in weight, with a noticeable decrease in feed intake.

[Real Case]

In May 2021, after our company’s Cherry Valley ducklings arrived at farmer Wang’s meat duck farm, they began suffering massive mortality starting on the fourth night—due to farmer Wang’s decision to cut costs by not using the company-recommended reovirus antibody. The peak of deaths persisted until the eighth day, after which it finally started to decline. Post-mortem examinations revealed that all spleens were dark red, with white pinpoint necrosis or complete necrosis visible on their surfaces. Meanwhile, the livers showed diffuse small white spots, and yolk absorption remained incomplete. Additionally, the flock exhibited poor uniformity across the entire group. Surviving ducks displayed significantly weakened immunity, making them highly susceptible to secondary bacterial infections such as E. coli, serositis, perihepatitis, pericarditis, and air sac inflammation. As a result, the overall growth and development of the duck population slowed dramatically, while ongoing mortality continued to inflict substantial economic losses. As illustrated in the figure below: ：

[Differential Diagnosis of Similar Conditions]

Clinically for ducks "When diagnosing the "novel reovirus," it's important to differentiate it from similar liver lesions seen in diseases such as duck herpesvirus-induced necrotic hepatitis (white spot disease)."

[Prevention and Treatment]

1. Vaccination   Triple antibody for parvovirus, reovirus, and circovirus, administered on day 1.
2. Strengthen feeding management and sanitation & disinfection measures.   Feeding a complete daily ration, especially For ducklings within 10 days of age, ensure adequate supplementation of vitamins, trace elements, and protein. Implement strict environmental hygiene management and disinfection measures, including disinfecting water sources, sanitizing personnel entering and exiting the area, and cleaning feeding troughs daily.
3. Feed large amounts of glucose oxidase to support liver and kidney function, combined with antiviral traditional Chinese medicines such as Dàyèqīng, Banláigēn, Huanglian, and Huángqí as the main ingredients. Additionally, administer Huangqi polysaccharide in drinking water and use antibiotics like Neomycin, Florfenicol, Amoxicillin, and Cephalexin to prevent secondary infections.

[Summary]

The lessons learned from the outbreak caused by reovirus have made farmers fully realize that their insufficient attention led to significant losses—both for the company and themselves. At the same time, they’ve come to understand the critical importance and necessity of developing strong immune antibodies in the future. They also pledged never again to rely on luck or chance, committing instead to strictly following the technical staff’s expert guidance and adopting standardized farming practices.