Duck viral hepatitis

Duck viral hepatitis is

The duck hepatitis virus causes an acute, highly fatal infectious disease in young ducks. The disease is characterized by angular arch reversal as a clinical symptom, commonly known as "dorsal neck disease"; pathological changes are characterized by enlarged liver and bleeding spots of different sizes, bleeding spots, or mottled shapes.

Duck viral hepatitis continues to occur in various parts of China, morbidity and mortality rates are on the rise, the disease has brought serious economic losses to the duck industry.

1 Epidemiology

Source of infection: Sick ducks and latently poisoned adult ducks are the main sources of infection.

Route of transmission: The disease is mainly transmitted through contact, but also through respiratory tract infection, no vertical transmission. Infection in direct contact with a sick duck can also be transmitted at the level of food utensils, drinking water and feed contaminated with the manure of the sick duck.

Susceptible poultry: 4- to 8-day-old chicks are most susceptible to infection. Chicks under 3 weeks of age are more common, and adult ducks become the source of infection due to latent infection.

Predisposing factors: poor feeding management, lack of vitamins and minerals, damp duck houses, excessive feeding density, poor sanitary conditions, etc. can promote the occurrence of this disease.

Pathogenesis characteristics: The disease has the characteristics of acute onset, rapid transmission and high mortality; there is no obvious seasonality, mostly occurs in the season of hatching ducks, once the disease occurs, it spreads quickly in the flock of young ducks, and the incidence rate can reach 100%.

2 Clinical symptoms

The incubation period of the disease is generally 1 to 2 days, and the peak of death is reached on the 2nd to 3rd day after the onset of the disease.

At the beginning of the onset of the disease, the young ducks are mentally weak, loose with hair, shrunken necks, eyes half closed and sleepy, loss of appetite, to anorexia, hunger strike; shoot yellow white and green feces; some chicks suddenly die without any symptoms.

The diseased duck has neurological symptoms within 12 to 24 hours of onset, multi-sided lying, generalized convulsions, dyskinesia, turning in circles, spasmodic repeated kicking of the feet, the head is tilted backwards in an angle arch reversal, death after a few hours, and screams can occur before death.

3 Pathological changes

Characteristic lesions of sick ducks in the liver.

The beak ends and claw tips of the sick duck are dark purple in bruises.

Sick ducks have enlarged, brittle, yellowish or dark colors, and have bleeding spots of varying sizes on the surface of the liver.

The gallbladders of the sick duck are oblong in shape, full of bile, and the bile is brown, grass green, or reddish.

The spleen of the sick duck is sometimes enlarged and mottled.

Most of the kidneys of sick ducks are congested, swollen, and the blood vessels are obvious, showing dark purple branches.

In some sick ducks, if cooked, pericardial effusions may sometimes be seen, and in severe cases, pericarditis occurs, with yellowish exudates and cellulose flakes in the air sacs.