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

• Published in: MMWR. Morbidity and mortality weekly report 2024-08, Vol.73 (34), p.734-739
• Main Authors: Drehoff, Cara C, White, Elizabeth B, Frutos, Aaron M, Stringer, Ginger, Burakoff, Alexis, Comstock, Nicole, Cronquist, Alicia, Alden, Nisha, Armistead, Isaac, Kohnen, Allison, Ratnabalasuriar, Radhika, Travanty, Emily A, Matzinger, Shannon R, Rossheim, Alexandria, Wellbrock, Aleigha, Pagano, H Pamela, Wang, Dennis, Singleton, Jordan, Sutter, Rebekah A, Davis, C Todd, Kniss, Krista, Ellington, Sascha, Kirby, Marie K, Reed, Carrie, Herlihy, Rachel
• Format: Article
• Language: English
• Subjects: Adult; Agriculture; Animals; Avian flu; Avian influenza; Avian influenza viruses; Clusters; Colorado - epidemiology; Conjunctivitis; Dairy cattle; Euthanasia; Farmworkers; Female; Genotype & phenotype; Genotypes; Health care access; Humans; Illnesses; Infection; Infections; Influenza; Influenza A; Influenza A Virus, H5N1 Subtype - isolation & purification; Influenza in Birds - epidemiology; Influenza, Human - epidemiology; Male; Medical personnel; Medical research; Medicine, Experimental; Middle Aged; Occupational exposure; Occupational Exposure - adverse effects; Occupational health; Outbreak Report; Personal protective equipment; Population decline; Poultry; Poultry industry; Public health; Questionnaires; Severe acute respiratory syndrome coronavirus 2; Viruses; Workers; Young Adult
• ISSN: 0149-2195; 1545-861X; 1545-861X
• DOI: 10.15585/mmwr.mm7334a1

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.