The numbers of birds affected by highly pathogenic avian influenza (HPAI) continues to rise, jumping by over 2 million since Dec. 27. The total number birds in the U.S. affected by the virus since the initial discovery in February 2022 has now surpassed 79.5 million, according to USDA’s Animal and Plant Health Inspection Service.

APHIS data shows the largest case over the last week was a commercial table egg pullet operation of 1.36 million birds in Hardin County, Ohio, confirmed on Dec. 27. California also reported three new cases in commercial table egg operations. A table egg pullet operation of 151,000 birds in Marin County, Calif., and two commercial table egg laying operations of 54,000 birds and 37,300 birds in Sonoma County confirmed the virus.

Meanwhile, Michigan and Minnesota reported two turkey operations with the virus. The Michigan operation of 31,000 turkeys was located in Muskegon County and the Minnesota operation of 78,800 birds was located in Todd County. A commercial upland game operation of 98,300 birds also detected the virus.

WOAH calls for review

The World Organization of Animal Health (WOAH) reported Dec. 28 that avian influenza has had a staggering toll, with over 500 million birds lost to the disease worldwide since 2005. The recent shift in the disease’s ecology and epidemiology has heightened global concern as it has spread to new geographical regions. It has also caused unusual die-offs in wild birds and led to an alarming increase in mammalian cases. Because of the rapidly evolving nature of the virus and changes in its patterns of spread, WOAH is calling for a review of existing prevention and control strategies. To effectively contain the disease, protect the economic sustainability of the poultry sector and reduce potential pandemic risks, all available tools must be reconsidered, including vaccination, the organization said.

“Given recent developments in its epidemiology, and the increasing circulation of high pathogenicity avian influenza (HPAI) in wild animals, stricter biosecurity measures and mass culling of poultry may no longer be sufficient to control the disease,” WOAH stated. “With the seasonal north-south migration of wild birds, countries must be prepared for an increase in outbreaks and should consider complementary approaches, such as vaccination, in line with existing international animal health and welfare standards.”

Even so, WOAH said the use of vaccination in poultry against HPAI remains the decision of each nation and should be tailored to the specific epidemiological and socioeconomic context, and the needs and capacities of each country or region. Further, the implementation of avian influenza vaccination programs “requires a careful balance between disease control and maintenance of safe international trade,” the organization added.