Human Infection with Eurasian Avian-Like Swine Influenza A(H1N1) Virus, the Netherlands, September 2019

E urasian avian-like swine influenza A(H1N1) vi- ruses (IAVs) are entirely derived from a precursor virus of avian origin (1) and have been enzootic in the swine population in Europe since 1979 and in Asia since 1993.Zoonotic infections with such viruses, which are then termed H1N1 variant (H1N1v) viruses, occur sporadically.Most cases occur in humans who have direct exposure to pigs.Since 1986, several human cases of Eurasian avian-like H1N1 swine IAV have been reported in Europe (2-4) and China (3,5).These events reflect the possibility of Eurasian avian-like H1N1 swine IAV transmission from swine to humans.In this study, we report an infection with a Eurasian avian-like H1N1 swine IAV in a pig farmer and his pigs in a herd in the Netherlands.We also conducted whole-genome characterization of viruses from the man and the pigs. The StudyOn September 18, 2019, acute respiratory disease was observed in a 43-year-old man (farmer) and his 14-week-old fattening pigs and gilts.The pigs of this closed farm showed coughing, anorexia, tachypnea, dyspnea, and lethargy.Two days earlier, a 44-year-old man (animal caretaker) had reported similar symptoms.The sows of this herd (n = 420) were vaccinated against swine IAVs with Respiporc FLU3 vaccine (Ceva, https://www.ceva.com),but the farmer and animal caretaker were not recently vaccinated against human seasonal influenza viruses.Both humans and the pigs recovered completely within 10 days after the first appearance of signs or symptoms.Family members and close contacts of the men did not show development of influenza-like symptoms.Six days after onset of disease, nasal swab samples were collected from the farmer, the animal caretaker, and 6 symptomatic pigs.Human samples were collected by self-sampling, and informed consent was obtained from the farmer and the animal caretaker.Subsequently, samples were shipped to the Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University (Merelbeke, Belgium).Upon inoculation into MDCK cells, IAV was isolated from the sample of the farmer and from a pooled sample of the pigs; no virus was isolated from the animal caretaker.Public health authorities in the Netherlands were notified about the H1N1v infection.The human H1N1v isolate was named A/Netherlands/ Gent-193/2019, and the swine H1N1 isolate was named A/swine/Netherlands/Gent-193/2019.Virus neutralization tests with swine antiserum against swine IAVs of the H1N1, H1N2, and H3N2 subtypes showed an antigenic relationship between both newly discovered isolates and Eurasian avianlike H1N1 swine IAVs from 1998 and 2010, as well as the prototype influenza A(H1N1)pdm09 (pH1N1) A/ California/04/2009 virus.Serologic cross-reactivity with H1N2 or H3N2 swine IAVs was not observed (Table 1). Initial analyses by multiplex real-time reverse transcription PCRs (6) and whole-genome next-generation Human Infection with Eurasian Avian-Like Swine Influenza A(H1N1)