Systematic Veterinary Virology

SYMPTOMS

• Clinical signs include letharginess, lose of balance, spasmodic paddling, anorexia and sudden death with opisthotonos within a few days. At death the head is usually drawn back in the opisthotonos position.
• The whole disease sequence is rapid and can take as little as 1–2 hours.
• The clinical course of DHV Type II infection is similar to that of Type I and  occur in ducklings immune to Type I infection.
• DHV Type III infections occur in ducklings despite immunity to Type I virus. The clinical course of Type III infection is less severe, and mortality is rarely >30%.