Maryland Backyard Flock Tests Positive for Bird Flu as US Cattle Herds and Human Cases Continue to Rise

This is Bird Flu Bulletin: Daily H5N1 Update, bringing you the latest on the avian influenza outbreak. Today is Wednesday, September 10, 2025. Top stories: First, authorities in Maryland report that a backyard flock in Anne Arundel County has tested presumptive positive for highly pathogenic H5 avian influenza. The Maryland Department of Agriculture confirmed this preliminary result from the Frederick Animal Health Laboratory, marking the third affected backyard flock in the county this year. State and federal officials are conducting further testing and implementing containment measures. Second, the U.S. Department of Agriculture Animal and Plant Health Inspection Service has confirmed one new infected cattle herd in Arizona in the last 24 hours. This brings the national total to 1,074 affected cattle herds across 17 states since the outbreak reached U.S. dairy herds in March 2024. While most outbreaks remain concentrated in commercial and backyard poultry flocks, cattle infections continue to be monitored closely by federal agencies. Third, the Centers for Disease Control and Prevention has not reported any new confirmed human H5N1 cases in the United States in the last 24 hours. The country’s total stands at 70 confirmed cases for the outbreak, with three already identified in 2025. According to the CDC, 41 of these cases have been linked to dairy cattle exposure, 24 to commercial poultry, and two to backyard flocks. There have been no reports of onward human-to-human transmission. Changes in case numbers: Compared to yesterday, there have been no changes in the total number of confirmed human H5N1 cases. However, with the new presumptive positive in Maryland and recent cattle herd detection in Arizona, animal case counts continue to inch upward. Guidance from health authorities: The CDC reiterates that the current public health risk remains low for the general population, but urges vigilance among agricultural and animal-handling workers. Good hygiene, the use of gloves and masks, and restricting movement between animal facilities are strongly recommended. The CDC also reminds the public that national flu surveillance will now include H5N1 updates and that animal outbreak data can be found on the USDA’s website. Expert interview: We spoke with Dr. Marie Kenner, infectious disease specialist at Johns Hopkins, about the ongoing outbreaks. “With every new animal case, there is a fresh opportunity for the virus to adapt,” Dr. Kenner warned. “That’s why swift containment and monitoring are critical. Still, there is currently no evidence of sustained human-to-human transmission, which remains the greatest concern from a pandemic perspective.” Looking ahead: Tomorrow, officials in Maryland are expected to release confirmatory results for the Anne Arundel County flock and will update on any further containment measures. The USDA’s next weekly summary on cattle herd monitoring is anticipated, providing further context on the spread in the This content was created in partnership and with the help of Artificial Intelligence AI.