What is Newcastle Viral Infection ?

Newcastle viral infection is an aggressive paramyxovirus that can cause devastation to bird populations. An outbreak in California in 1972 killed millions of chickens and was responsible for the imported bird quarantine system we have today and upwards of 10,000 double crested cormorants in Canada perished in another outbreak in 1990. This virus attacks the respiratory system most intensely, however, the digestive and nervous systems can also be affected. There is no cure for this diseases, but there are vaccines available to help develop immunity to the virus.

The Newcastle virus is an aggressive virus that can attack birds of many species, both domestic and wild. There is no cure for this disease, but effective vaccines do exist.

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Symptoms of Newcastle Viral Infection in Birds

The symptoms of Newcastle disease typically start between two and twelve days after exposure to the virus and can include:

  • Circling
  • Coughing sneezing
  • Depression
  • Diarrhea
  • Difficulty breathing
  • Discharge from the eyes
  • Egg abnormalities
  • Excitability
  • Loss of coordination
  • Nasal discharge
  • Nervousness
  • Paralyzed wings or legs
  • Spasms
  • Sudden death
  • Swelling of the head and neck
  • Tremors
  • Weakness

Types

There are several strains of Newcastle disease that can infect birds as well as be utilized to create either live or killed vaccines. These strains of the virus can be broadly grouped into four pathotypes:

  • Avirulent - Strains of the Newcastle virus that create no actual disease would be considered avirulent
  • Lentogenic - Lentogenic pathotypes are less contagious and are less likely to cause mortality than all but the avirulent types, although egg production is often negatively impacted
  • Mesogenic - Strains that are classified as mesogenic are moderately contagious and typically have around a 50% mortality rate
  • Velogenic - Velogenic strains are the most virulent of the pathotypes and is not used in the creation of vaccines; the mortality rates from velogenic strains of Newcastle disease are generally very high

Causes of Newcastle Viral Infection in Birds

Newcastle disease is a virus that can be spread through the infected bird's nasal discharge, droppings, or through the dander or dust shed by the animal. The virus can survive in warm, humid environments without direct sunlight for several weeks, but can be destroyed by direct sunlight and dehydration. Differing species of birds have different levels of susceptibility to the virus; those that are most susceptible include domestic chickens, turkeys, ducks, and geese, as well as pigeons, parrots, cormorants, and canaries. This disease is also transmittable to humans, however, the illness is much milder, causing mild flu-like symptoms and conjunctivitis.

Diagnosis of Newcastle Viral Infection in Birds

In acute outbreaks of Newcastle virus, death may be rather sudden, and diagnosis in these cases will occur during the autopsy. Birds who have succumbed to Newcastle viral infection will exhibit small red or purple spots on the mucous membranes around their proventriculus and gizzard as well as inflammation of the duodenum. For birds that are showing symptoms consistent with Newcastle virus infection or that has had confirmed or suspected exposure to a Newcastle infected bird, the veterinarian visit will generally start with a complete physical examination. 

The patient will be weighed and measured, and its condition will be evaluated from head to toe. Standard blood tests such as a complete blood count and biochemical profile may reveal an increased level of white blood cells indicating that an infection is present. If an infection by the Newcastle virus is suspected your veterinarian will confirm the diagnosis by employing tests such as: 

  • Enzyme-linked immunosorbent assay (ELISA) 
  • Polymerase chain reaction (PCR) assay
  • Sequence technology testing

Treatment of Newcastle Viral Infection in Birds

There is no cure for Newcastle viral infection, although antibiotics may be prescribed to fight off any secondary bacterial infections. Any bird that is suspected of having Newcastle virus should be quarantined right away, and a veterinary professional contacted in order to confirm the diagnosis and contact the proper authorities. The best course of action with this virus is to ensure that your animal is properly protected from getting the virus in the first place. 

There are both live and killed virus vaccines in use to protect against this often fatal disorder, and in many countries, vaccination is required in order to prevent outbreaks. Recommended vaccinations schedules include vaccination for the Newcastle virus for chickens at between one and twenty-one days old depending on the type of vaccine used, and for turkey chicks at six to eight weeks of age. These vaccines are generally distributed to new chicks by adding it to the drinking water or by spraying the poultry with a coarse spray.

Recovery of Newcastle Viral Infection in Birds

It is possible for even properly vaccinated birds to contract and even succumb to Newcastle virus, although it is much less likely. The avian smuggling industry is a large contributor to the spread of this particular virus and certification that the animals were born in the country or legally imported is essential as is a U.S. health certificate. Even certified animals should be kept separately from other flocks or birds for four to six weeks to ensure that there are no dangerous viral or bacterial infections that have not yet been spotted. The Newcastle virus also infects wild birds, particularly pigeons, cormorants, and canaries, so it is important to prevent wild birds from roosting in the living areas of poultry or from interacting too closely with your pet birds.