In an effort to curb further spread of the highly pathogenic avian influenza virus and implement additional control measures to protect the dairy and poultry industries and public health in Colorado, the Colorado Department of Agriculture is implementing mandatory statewide surveillance for all Colorado Department of Public Health and Environment licensed commercial cow dairies. This action will help identify any additional infected dairies with the virus with the goal of preventing further spread of the disease. The order for statewide mandatory bulk-tank HPAI testing by the Commissioner of Agriculture was issued July 22, 2024.
“We have been navigating this challenging, novel outbreak of HPAI in dairy operations for nearly three months in Colorado and have not been able to curb the spread of disease at this point,” said Dr. Maggie Baldwin, state veterinarian. “We have seen devastating impacts of this disease not only to our dairy industry, but our poultry industry as well. With the strong support of the dairy and poultry industries, we feel that this is the best next step in order to protect these vital industries in our state.”
Colorado is now experiencing spillover of the dairy H5N1 strain, genotype B 3.13, into commercial poultry facilities. Colorado has had two spillover events, confirmed through genomic sequencing, and one presumptive spillover event from dairy operations into commercial poultry operations that have resulted in the death and depopulation of more than 3.2 million domestic chickens during the month of July.
The statewide surveillance will take place under the joint supervision of CDA and CDPHE with support from USDA and will remain until further notice by the commissioner of agriculture or state veterinarian.
“We appreciate the ongoing cooperation and partnership with both the poultry and dairy industries,” said Colorado Commissioner of Agriculture Kate Greenberg. “Mandatory surveillance of highly pathogenic avian influenza across all of Colorado’s Grade A commercial dairies is a critical next step to tamping down the virus and protecting the food system. Ongoing cooperation is key to supporting workers’ health and safety, protecting animal health and welfare, and minimizing the spread of the virus.”
HPAI outbreak background
Beginning in April 2022 and continuing through March 2024, highly pathogenic avian influenza impacted 33 confirmed poultry flocks in the state of Colorado, resulting in the loss of more than 6.3 million domestic poultry in the state.
In March 2024, the USDA confirmed the detection of H5N1 avian influenza virus in dairy cattle in the Texas Panhandle region. The virus has spread to 13 states, impacting more than 168 dairies since the beginning of the outbreak. Dairy cattle infected with the H5N1 virus appear to recover with supportive care. Signs of infection in cattle include loss of appetite, reduced milk production and colostrum-like milk.
The spread of this current strain of the virus has been via cow-to-cow transmission and farm to farm. Unlike previous outbreaks, the virus is not currently being spread by wild birds. At this time, Colorado has the highest number of reported cases of HPAI in dairy herds in the United States, with 47 confirmed detections.
CDA is also working with CDPHE to identify and monitor both livestock and human impacts. CDPHE offers testing to anyone who has symptoms of avian flu and was exposed to infected or potentially infected animals or humans. CDC continues to state that risk to the general public is low, and that there is no evidence of virus transmission from person to person.
