In 1971, a major outbreak of Exotic Newcastle Disease occurred in southern California.  The containment effort cost $56 million and required the destruction of 12 million birds from over 1,300 infected flocks.  Exotic Newcastle is so virulent that many birds die without showing any clinical signs; mortality rates approaching 100% are not uncommon among infected flocks.   A particularly nasty variant of a virus found throughout the world, Exotic Newcastle is considered one of the most infectious diseases of poultry in the world.  Its mortality rates, its ease of transmission, and its relative hardiness all combine to make Exotic Newcastle Disease a potentially devastating weapon in the wrong hands.

Within 2-15 days after a flock is exposed to Exotic Newcastle Disease, farmers will note a marked drop in egg production.  Soon after this the mass deaths begin; as much as 15% of the flock can be lost within the first 24 hours of onset.  (The deaths are so quick, and so asymptomatic, that many farmers originally attribute them to poisoning rather than disease).   In the birds who die during the second wave of infection, swollen necks and internal lesions will be seen.  Surviving chickens frequently show major neurological damage, seen as tremors, paralysis and drooping wings, as well as damage to the reproductive system and decreased egg production.   Once introduced into a farm, the virus spreads through the movement of apparently healthy chickens.  It can also be introduced on boots, sacks, crates and egg trays, and can also be carried by mice or rats throughout the surrounding area.  To make matters worse, Exotic Newcastle Disease can also infect wild birds.  Some will die from this infection (the United States and Canada have seen massive losses in their Wild Cormorant population from Exotic Newcastle).  Others, like finches, canaries and sparrows, will show no symptoms but will remain capable of transmitting the disease to domestic flocks which they contact.

Since the 1960s there have been both live and killed vaccines to prevent Newcastle Disease.  These have been effective in preventing the milder forms of the illness, and are regularly used today on most chicken farms.  In the event of an attack using the more pathogenic varieties, these viruses could prove more curse than blessing.  Chickens who have been vaccinated against Newcastle typically show milder symptoms and lower mortality rates in an epidemic – but that does not stop an exposed but asymptomatic bird from carrying the illness to other chickens, and it may cost valuable time as the birds are misdiagnosed with avian influenza or other less dangerous diseases.

The Exotic Newcastle virus can survive for several weeks in a warm and humid environment on birds’ feathers.  There are many cases in veterinary literature of transmission of this disease on the boots of farmworkers, or on the gear of people who worked in poultry processing plants.  Many of these plants face regular and chronic labor shortages, and regularly hire illegal immigrants and others to make up the shortfall.  A gang of terrorists working their way through America’s poultry farms could spread an industry-crippling infection within a few weeks, and leave little or no paper trail in the process.