Virulent Newcastle disease resurged in Southern California as people broke quarantines by moving birds and farming equipment, state authorities said.
After two months without any known infections, state and federal authorities confirmed new ones starting in mid-November and continuing through the end of the year. Their investigation led to a community in San Bernardino County.
“We now have 20 new cases under investigation, all linked to the recent Bloomington area outbreak,” State Veterinarian Annette Jones wrote in a Dec. 23, 2019, alert.
By Dec. 31, all but three of the new infections were in San Bernardino County, with two in Riverside County and one in Los Angeles County, according to U.S. Department of Agriculture data.
Virulent Newcastle disease is a contagious, untreatable, and deadly viral respiratory infection of birds. State and federal agriculture authorities have quarantined and depopulated poultry since the outbreak began in spring 2018.
“As a reminder, last year the disease was spread from San Bernardino to LA and Riverside counties and beyond, leading to widespread highly infected areas, infected poultry farms, the death of over 1.2 million birds, and significant financial and emotional strain on poultry owners and disease control agencies,” Dr. Jones said in December’s alert.
The disease spread to about 470 places, most of them homes with backyard flocks, according to USDA data. But most of the deaths from the disease occurred in the four commercial poultry facilities with infections.
State animal health authorities warn that birds spread the disease before becoming ill, so halting poultry movement is the only way to stop the outbreak.
The California Department of Food and Agriculture’s Animal Health and Food Safety Services began imposing quarantines on poultry and other owned birds in affected areas in May 2018. Starting in February 2019, the quarantine affected birds throughout Los Angeles County and in portions of San Bernardino and Riverside counties. The CDFA’s quarantine notice states that the quarantine also applies to eggs, manure, feed, carcasses, feather, and poultry-use equipment.
The Dec. 23 alert states that people also carry the virus on their hands and feet. The virus survives long-distance trips, as shown by single infection sites in Utah, Arizona, and Northern California.
In a Dec. 31 announcement, CDFA officials warned poultry producers they need to maintain heightened biosecurity standards at least through March 1, when the state will provide an updated risk evaluation.
USDA Animal and Plant Health Inspection Service officials indicated in December they plan to create a program that would certify poultry breeding flocks are free from Newcastle disease and allow continued trade during an outbreak. But they delayed the plan later that month because they found that adding such a program requires updating federal regulations.
The Newcastle disease–clean program, through the National Poultry Improvement Plan, would let flock owners continue engaging in trade during a Newcastle outbreak if those owners use vaccination or serologic testing to prove their flocks are unaffected. The program would accept flocks only from states requiring that veterinarians report all confirmed Newcastle infections and that animal health laboratories look for Newcastle infections when investigating unexplained deaths, respiratory disease, or egg production declines.