As of mid-June, portions of California, Nevada, Arizona, and Texas remained under quarantine as a result of outbreaks of exotic Newcastle disease in commercial and privately owned poultry.

Since the fatal viral disease was first detected in October 2002, a federal task force has been working with affected states to eradicate it. Those efforts have met with some success as restrictions on bird movement in New Mexico and some Texas counties were lifted June 5.

But exotic Newcastle disease is still active in the western United States, most notably in Southern Californian, where nine counties were still quarantined at press time and nearly 4 million birds have been destroyed. More than 800 people are working in California to eradicate the disease, and a statewide ban on public exhibitions of poultry continues.

The last outbreak of exotic Newcastle disease in California's commercial poultry flocks was 1971, resulting in the loss of 12 million birds at a cost of $56 million.

Birds infected with exotic Newcastle disease often die without showing any clinical signs. All bird species are susceptible to the virus, which attacks the respiratory, nervous, and digestive systems. The virus is passed through direct contact between healthy birds and the bodily discharges of infected birds.

Humans can be infected with exotic Newcastle disease, with the most common symptom being conjunctivitis.