Cluster of Influenza A(H5) Cases Associated with Poultry Exposure at Two Facilities - Colorado, July 2024.

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.

Déclaration de conflit d'intérêts

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Radhika Ratnabalasuriar reports receipt of per diem payment as an emergency medicine physician from Rocky Mountain Regional VA Medical Center, Intermountain Health Saint Joseph Hospital, and Colorado Kaiser Permanente Group. Emily A. Travanty reports serving as the Colorado Department of Public Health & Environment Institutional Review Board chair and community public health membership on the University of Colorado–Anschutz Medical Campus Institutional Biosafety Committee. Rachel Herlihy reports receipt of sponsorship for travel to annual and working meetings from the Council of State and Territorial Epidemiologists and the Association of Public Health Laboratories. No other potential conflicts of interest were disclosed.