Duck virus enteritis (DVE), commonly known as duck plague, is an acute and contagious disease of wild and domestic anseriforms (ducks, geese, and swans). Muscovy ducks are particularly susceptible to infection, while other duck breeds, such as call ducks, appear to be more resistant. DVE is caused by infection with a herpesvirus, specifically, the anatid herpesvirus 1 (AnHV-1) of the family Herpesviridae
. The severity of the disease depends on the virus strain and the resistance of the species of duck infected. DVE primarily affects the duck's gastrointestinal system; causing vascular damage, tissue hemorrhages, Gastrointestinal mucosal eruptions, and necrosis of organs. DVE outbreaks have been documented in both wild and domestic waterfowl worldwide, with the exception of Australia. Most outbreaks occur during the spring to early summer. Ducks of all ages are susceptible to DVE, however it is most commonly seen in mature, adult ducks.
DVE is usually associated with sudden, high, persistent flock mortality during outbreaks. Common clinical signs observed in adult ducks include:
- Penile prolapse: Adult male ducks often die with a prolapsed penis.
- Weakness: Ducks often will be so weak that they are unable to stand or hold their head up. Drooped wings are also observed often.
- Diarrhea: Affected ducks often have bloody or greenish-watery diarrhea, often with soiled vents.
- Polydipsia: Increased water intake due to excessive thirst.
- Generalized illness signs: Lethargy, fever, reduced appetite, partially closed eyelids, light sensitivity, ruffled feathers, and depression.
- Sometimes affected ducks will be found dead, with the bird showing no clinical signs of sickness prior. This is especially the case with the more sensitive species, such as the Muscovy duck.
When young ducklings are affected (typically between 2 to 7 weeks of age), clinical signs most often observed include:
- Lacrimation (tearing eyes)
- Weight loss
- Nasal exudate
- Blood-stained vent
- Blood dripping from nostrils
- Blue colored beaks
Signs of DVE in ducks can appear similar to several other diseases, and will need to be differentiated from duck virus hepatitis, necrotic enteritis, lead poisoning, and pasteurellosis.
DVE is spread vertically (from breeding duck to the duckling hatching from the egg) or horizontally (through direct contact with an infected bird or indirectly from a contaminated environment). Wild migratory or free-ranging waterfowl are notoriously known to be silent carriers of the virus, often showing no clinical signs of infection. The disease is frequently seen when domestic and wild waterfowl come in contact with one another, such as in residential settings or urban ponds. Any ducks that recover from DVE may become persistently infected and shed the virus in their feces, exposing other birds to infection for several years after.
In domestic ducks, the incubation period for DVE ranges from 3 to 7 days. After initial clinical signs appear, most ducks will die within 1 to 5 days.