Newcastle disease (Paramyxovirus 1)
Paramyxovirus 1 or Newcastle disease (ND) is a highly contagious viral disease affecting poultry of all ages. Occasionally, it can be contracted as conjunctivitis in humans and it may be necessary to use preventive measures, such as gloves and goggles, during outbreaks. In chickens, ND can affect the nervous, respiratory or reproductive systems. Morbidity is usually high and mortality varies widely from 0 to 100%. These higher mortality rates can be seen in velogenic disease in unvaccinated stock.
There are four forms of ND:
- Lentogenic — Mild disease, sometimes subclinical. Can affect any age. Strains can be developed as vaccines.
- Mesogenic — Mortality and nervous signs in adult. These viruses have sometimes been used as vaccines in previously immunized birds.
- Neurotropic Velogenic — Acute and fatal in chickens of any age, causing neurological and some respiratory signs. Intestinal lesions are absent.
- Velogenic Viscerotropic (VVND) — Sometimes called “asiatic” or exotic, it is highly virulent for chickens, though less for turkeys.
ND is transmitted by direct contact with the droppings or respiratory discharges of infected birds. The virus can live for a long time in the environment and can be spread by objects such as shoes, clothing and equipment that have become contaminated by infected birds. The ND virus is quite sensitive to disinfectants, fumigants and sunlight.
Signs of ND can vary widely, depending on the nature of the infecting virus, the infective dose and the degree of immunity from previous exposure or vaccination.
- Sudden death
- Loss of appetite
- Nervous signs
- Twisted neck
- Severe drop in egg production
There are no treatments for ND, though antibiotics can be used to control secondary bacterial infections. Prevention strategies include quarantine, biosecurity, all-in/all-out production and vaccination.