The attribution of human seasonal influenza H3N2 virus detection to the collector, not avian sources, during the 2022 highly pathogenic avian influenza outbreak in Pennsylvania, USA-implications for biosafety and biosecurity

Authors: TEWARI, DEEPANKER - Pennsylvania Veterinary Laboratories; SEKHWAL, MANOJ - Pennsylvania Animal Diagnostic Laboratory System; KILLIAN, MARY - Animal And Plant Health Inspection Service (APHIS); ZELLERS, COREY - Pennsylvania Veterinary Laboratories; NICHOLSON, CHRISLYN WOOD - Animal And Plant Health Inspection Service (APHIS); SCHRODER, BETSY - Pennsylvania Bureau Of Epidemiology; Spackman, Erica; HAMBERG, ALEX - Pennsylvania Veterinary Laboratories

Submitted to: Vector-Borne and Zoonotic Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2024
Publication Date: 12/13/2024
Citation: Tewari, D., Sekhwal, M.K., Killian, M.L., Zellers, C., Nicholson, C., Schroder, B., Spackman, E., Hamberg, A. 2024. The attribution of human seasonal influenza H3N2 virus detection to the collector, not avian sources, during the 2022 highly pathogenic avian influenza outbreak in Pennsylvania, USA-implications for biosafety and biosecurity. Vector-Borne and Zoonotic Diseases. 2024(4):315-319. https://doi.org/10.3390/zoonoticdis4040027.
DOI: https://doi.org/10.3390/zoonoticdis4040027

Interpretive Summary: A sample from a poultry flock was found to be positive for influenza by the veterinary diagnostic lab that processed the sample. Further characterization of the genetics of the virus showed that the sample was consistent with common seasonal influenza in people, not bird flu. Investigation of the event revealed that the individual who collected the sample was feeling sick and had reported to a clinic the same day that the sample was collected. The clinic had confirmed that the individual was infected with the flu. The case shows how a false positive was produced by cross contamination during sample collection of the poultry flock, which can impact the disposition of the flock. Further characterization or investigation of unexpected sample results is a good practice to confirm the test result.

Technical Abstract: Highly Pathogenic Avian Influenza (HPAI) surveillance for influenza A virus (IAV) in the United States is conducted with National Animal Health Laboratory Network (NAHLN) real-time reverse-transcriptase polymerase chain reaction (rRT-PCR). Samples showing presence of IAV are confirmed and characterized at the national reference laboratory. During the H5N1 HPAI outbreak in 2022, our laboratory reported the detection of IAV in a PA commercial chicken flock by rRT-PCR targeting the matrix gene, which was negative for the H5/H7 subtypes. IAV was not detected by additional sampling the following day with rRT-PCR. The virus was characterized as a human seasonal H3N2 with whole genome sequencing (WGS). Further investigation revealed that the collector who visited the farm was diagnosed with an IAV infection. This report emphasizes importance of farm biosafety and biosecurity, conducting regular reviews of worker safety protocols, and the importance of advanced molecular techniques like WGS for viral characterization and epidemiology.