Bidirectional Human–Swine Transmission of Seasonal Influenza A(H1N1)pdm09 Virus in Pig Herd, France, 2018

Abstract

In 2018, a veterinarian became sick shortly after swabbing sows exhibiting respiratory syndrome on a farm in France. Epidemiologic data and genetic analyses revealed consecutive human-to-swine and swine-to-human influenza A(H1N1)pdm09 virus transmission, which occurred despite some biosecurity measures. Providing pig industry workers the annual influenza vaccine might reduce transmission risk.

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

“…The molecular detection approaches followed by sequencing are largely used for the research focusing on the influenza virus epidemiology [73,78,82,87,94,128,146,150]. [5,37,43,45,46,61,74,88,137,157,171,176,188,191,199,207,215,[219][220][221]241,243,248,250,263,289,290,301,306,307,326,334] IAV, IDV, H1N1, H1N2, H3N2, A(H1N1)pdm09 [45,192,227,282,285,287,302,322] 8. Blood/ serum IDEXX Ab test, ELISA, HI assay, NI assay, VN assay, MN assay, western blot, virus isolation (MDCK cells) H1N1, H1N2, H3N2, A(H1...…”

“…Europe Belgium H1N1, H1N2, H3N2 None [179][180][181] Denmark H1N1, H1N2, H3N2 None [182][183][184] United Kingdom H1N1, H1N2, H3N2, A(H1N1)pdm09, H1N7 IBV, ICV [185][186][187][188][189][190][191][192] Finland H1N1, H1N2, H3N2, A(H1N1)pdm09 None [193,194] France H1N1, H1N2, H3N2, A(H1N1)pdm09 None [195][196][197][198][199] Germany H1N1, H1N2, H3N2, A(H1N1)pdm09 None [200][201][202][203] Greece H1N1, H1N2, H3N2, A(H1N1)pdm09 None [204] Italy H1N1, H1N2, H3N2, A(H1N1)pdm09 IDV [205][206][207][208][209][210][211][212][213][214][215][216][217] Spain H1N1, H1N2, H3N2 None [218][219][220][221] Netherlands H1N1, H1N2, H3N2 None [222] Norway A(H1N1)pdm09 None [223][224]…”

“…Few days later, the farmer and the veterinarian both developed the influenza-like symptoms. The farmer was later diagnosed with A(H1N1)pdm09 virus [199].…”

Virus persistence in pig herds led to successive reassortment events between swine and human influenza A viruses, resulting in the emergence of a novel triple-reassortant swine influenza virus

“…Based on genetic similarity, it seemed unlikely that the triple reassortant virus was introduced in toto thanks to importations. The Mpdm segment acquired by the H1 av N2 virus during the second reassortment could have been provided by a H1N1pdm virus, either subsequent to a human-to-swine transmission during the 2013–2014 seasonal epidemic or from a swine-to-swine transmission as this virus also circulates in pigs in France and other European countries [3, 9, 22]. What is obvious is that the Mpdm gene did not originate from a H1N1pdm strain belonging to the swine-divergent H1N1pdm lineage that was recently identified in pigs in France [9].…”

“…That is why this study recalls the necessity to improve the management of influenza infections inside holdings to avoid swIAV persistence, e.g., by the export of consecutive piglet batches which was identified as the most efficient measure to limit recurrent swIAV infection in farrow-to-finish pig farms [30]. Finally, biosecurity measures should include actions aimed at reducing IAV interspecies transmissions, e.g., to limit the entry of ILI’s people, to encourage the use of protective mask and gloves, and to provide pig industry workers the annual influenza vaccine [22].…”