Duck plague virus

Duck plague (also known as duck viral enteritis) is a worldwide disease caused by Anatid alphaherpesvirus 1 of the family Herpesviridae that causes acute disease with high mortality rates in flocks of ducks, geese, and swans. It is spread both vertically and horizontally—through contaminated water and direct contact. Migratory waterfowl are a major factor in the spread of this disease as they are often asymptomatic carriers of disease. The incubation period is three to seven days. Birds as young as one week old can be infected. DEV is not zoonotic. Duck plague (also known as duck viral enteritis) is a worldwide disease caused by Anatid alphaherpesvirus 1 of the family Herpesviridae that causes acute disease with high mortality rates in flocks of ducks, geese, and swans. It is spread both vertically and horizontally—through contaminated water and direct contact. Migratory waterfowl are a major factor in the spread of this disease as they are often asymptomatic carriers of disease. The incubation period is three to seven days. Birds as young as one week old can be infected. DEV is not zoonotic. Upon exposure to DEV there is a 3-7 day for domestic fowl and up to a 14 day for wildfowl incubation period for the onset of symptoms. Sudden and persistent increases in flock mortality is often the first observation of DEV. Symptoms in individual birds include loss of appetite, decreased egg production (nearing 20-40% decreases), nasal discharge, increased thirst, diarrhea, ataxia, tremors, a drooped-wing appearance, and in males a prolapsed penis. Mortality rates for DEV may reach 90 percent. Death usually occurs within 5 days after onset of symptoms. The clinical signs of DEV 'vary with virulence of virus strain, species, sex, and immune system status' of the host. Due to the formation of diphtheroid plaques on the eyelids and the mucosae of the respiratory system and gastrointestinal system the bird may show ophthalmic signs and refuse to drink. Anatid alphaherpesvirus 1 can only infect birds of the Anseriformes order and Anatidae family, with the possible exception of coots. A study of lesions found in 'coots (order Gruiformes)' found similarities to DEV lesions. This could be evidence that DEV is able to 'cross to different orders and families' or 'adapted to new hosts.' Waterfowl species have differing susceptibility to DEV, with wild fowl tending to be more resistant. Nonwaterfowl have not been shown to be infected by duck plague. Blue-winged teal have been found to be one the most susceptible species and mallards one of the least. In another it took 300,000 more virus material to infect northern pintail than to infect blue-winged teal.