Newcastle Disease

Other Names: Avian Paramyxovirus, APMV-1

Cause

Newcastle disease (ND) is a viral disease of wild and domestic birds. There are many different strains of the ND virus that cause different degrees of disease in different bird species. A Scottish poem from 1897 is probably the first record of ND in wild birds. The poem refers to die-offs in domestic chickens as well as great cormorants and European shags.

Significance

Newcastle disease virus has caused major mortality events in wild double-crested cormorants in North America. The virus also causes one of the most economically significant diseases of domestic poultry.

Species Affected

ND has been reported in over 240 species of birds, and the virus can probably infect all bird species. Double-crested cormorants and rock doves (pigeons) are the two wild species in which outbreaks causing extensive mortality have been reported. White-pelicans, ring-billed gulls, and California gulls also died of ND during an outbreak in double-crested cormorants. ND virus has been known to cause high mortality in domestic poultry, and wild birds have been known to be the source of infection for domestic birds. ND virus can cause minor disease in humans, but is not considered a significant public health concern.

Distribution

Newcastle disease virus has a worldwide distribution. Outbreaks in double-crested cormorants occur in breeding colonies in March-September. In 1990 an outbreak of ND in double-crested cormorants in Canada resulted in the death of more than 10,000 birds. In the United States, outbreaks have been reported in wild cormorants at the Great Salt Lake, southern California, the Great Lakes region, and the Columbia River between Washington and Oregon. A domestic poultry flock in the Midwestern United States became infected with ND during an outbreak in cormorants in 1992. In 1997 an outbreak at the Salton Sea in California resulted in the death of about 2,000 cormorants. Outbreaks have been reported as recently as 2010 in double-crested cormorants in Minnesota, North Dakota, and Wisconsin. The disease has been suspected in Pennsylvania cormorants as recently as 2010, but not confirmed.

Transmission

Newcastle disease virus is highly contagious and is easily transmitted among susceptible birds. The virus is shed in the feces, body fluids, exhaled air, and eggs of infected birds, and it can be present in all body tissues. Birds become infected by inhaling virus particles or consuming contaminated food or water. The virus can survive for long periods of time outside of the host, so it can be transmitted by contact with contaminated inanimate objects. Humans can spread the virus to new locations by way of contaminated clothing, boots, and equipment.

Clinical

Rock pigeons and double-crested cormorants infected with ND most often show neurological signs. They may exhibit a loss of coordination, twisting of the head and neck, poor balance, tremors, and wing and/or leg paralysis. Cormorants that survive this disease often suffer from permanent wing or leg paralysis, usually on one side. Newcastle disease should be suspected when several birds are observed with one-sided wing paralysis. Birds with one paralyzed wing may be observed thrashing on the water; they are still able to dive, but cannot fly. Signs of neurologic disease are not always evident, but birds with this virus often have bloody diarrhea. In cormorants, only the juveniles show clinical illness, and mortality is usually limited to the young of the year. Most ND infections in other wild bird species are asymptomatic.

Diagnosis

Newcastle disease is diagnosed by identification of the virus.

Treatment

There is no treatment for Newcastle disease.

Management/Prevention

Vaccines are used to prevent Newcastle disease virus outbreaks in domestic poultry, and may be used in rare or endangered wild species. However, vaccination is not a practical option for free-ranging wild populations. ND virus can be transmitted between domestic and wild birds, so contact between domestic and wild birds should be prevented. Biosecurity is very important to prevent the spread of this virus between poultry farms and into the wild from infected premises. In the case of an outbreak, wildlife managers and poultry farmers must work together to minimize the impact of the disease on domestic and wild birds.