Cluster of Influenza A(H5) Cases Associated with Poultry Exposure at Two Facilities — Colorado, July 2024
Cara C. Drehoff, Elizabeth B. White, Aaron M. Frutos, Ginger Stringer, Alexis Burakoff, Nicole Comstock, Alicia Cronquist, Nisha B. Alden, Isaac Armistead, Allison Kohnen, Radhika Ratnabalasuriar, Emily A. Travanty, Shannon R. Matzinger, Alexandria Rossheim, Aleigha Wellbrock, H. Pamela Pagano, Dennis Wang, Jordan Singleton, Rebekah Sutter, C. Todd Davis, Krista Kniss, Sascha Ellington, Marie K. Kirby, Carrie Reed, Rachel Herlihy, H5N1 Field Investigation Team, H5N1 Field Investigation Team, Robyn Weber, Leovi Madera, Megan Vizina, Brene Belew-Ladue, Hannah Padda, Angiezel Merced-Morales, Ann Carpenter, Grace E. Marx, Lizette O. Durand, Scott Brueck
Abstract
Persons who work in close contact with dairy cattle and poultry that are infected with highly pathogenic avian influenza (HPAI) A(H5N1) virus are at increased risk for infection.In July 2024, the Colorado Department of Public Health & Environment responded to two poultry facilities with HPAI A(H5N1) virus detections in poultry.Across the two facilities, 663 workers assisting with poultry depopulation (i.e., euthanasia) received screening for illness; 109 (16.4%) reported symptoms and consented to testing.Among those who received testing, nine (8.3%) received a positive influenza A(H5) virus test result, and 19 (17.4%) received a positive SARS-CoV-2 test result.All nine workers who received positive influenza A(H5) test results had conjunctivitis, experienced mild illness, and received oseltamivir.This poultry exposure-associated cluster of human cases of influenza A(H5) is the first reported in the United States.The identification of these cases highlights the ongoing risk to persons who work in close contact with infected animals.Early response to each facility using multidisciplinary, multilingual teams facilitated case-finding, worker screening, and treatment.As the prevalence of HPAI A(H5N1) virus clade 2.3.4.4b genotype B3.13 increases, U.S. public health agencies should prepare to rapidly investigate and respond to illness in agricultural workers, including workers with limited access to health care.* Facility A was a large commercial operation with 1.8 million egg-laying poultry.Facility B was a large commercial operation with 1.3 million egg-laying poultry.Facility B was located in the same county as facility A, but the two facilities had no connection to each other. Confirmatory testing was conducted by the National Veterinary Services Laboratory (NVSL), and the virus was later identified as clade 2.3.4.4b genotype B3.13.Facility A received a confirmatory laboratory result by NVSL on July 8; facility B received confirmation by NVSL on July 16.