Introduction
Outbreaks of influenza A viruses (IAV) have caused considerable harm to
the animal and human health with several global socio-economic impacts
(McLeod, Morgan, Prakash, & Hinrichs, 2005). Wild aquatic birds such as
the Anseriformes and Charadriiformes are the major natural reservoirs of
IAV, except H17 and H18 subtypes detected in bats (Munster et al., 2007;
Tong et al., 2013). In addition to its natural reservoir circulation,
IAV can cross the species barrier and infect a wide range of hosts
including, canids, equids, humans, poultry, and swine (Joseph, Su,
Vijaykrishna, & Smith, 2017).
Wild waterfowl migration has a dominant role in the global influenza
virus spread (Franklin et al., 2019; Ren et al., 2016). Every year, low
pathogenic avian influenza (LPAI) outbreaks among waterfowl occur during
migration when contact rates among waterfowl populations are high (van
Dijk et al., 2014). Indeed, migratory wild birds are associated with
intra- and intercontinental dissemination of IAV as well as the
geographic dispersion of IAV subtypes in wild bird species and poultry
residents (Fourment, Darling, & Holmes, 2017; Humphreys et al., 2020).
The wildlife – livestock interface represents a significant source of
disease in domestic flocks (Wang, Jiang, Jin, Tan, & Xu, 2013). Some
production practices such as free-range farming may increase the
likelihood of contact among wild and domestic populations, and represent
a critical factor for persistence and transmission of IAV (Cappelle et
al., 2014). Likewise, backyard systems are considered suitable areas for
influenza surveillance due to the complex interactions between swine,
poultry, humans, and wild animals (Hamilton-West et al., 2012;
Jimenez-Bluhm et al., 2018).
Previous research has provided some insights into the dynamic of IAV at
the wildlife –livestock interface (Wiethoelter, Beltrán-Alcrudo, Kock,
& Mor, 2015). Phylogenetic analyses have revealed high sequence
homology among IAV circulating in pigs, poultry, and wild birds
(Bergervoet et al., 2019; Osbjer et al., 2016). Ecological and
phylogeographical analyses have shown that migratory waterfowl, domestic
ducks, free‐ranging animals, and agroecosystems are crucial in the
maintenance and viral spread (Wei, Lin, & Xie, 2015). Serological and
molecular studies of IAV have evidenced the viral circulation in
backyard farms situated close to “el Yali”, one of the most important
wetlands in South America (Bravo-Vasquez et al., 2016).
The Lerma marshes constitute a critical surveillance area where wild
ducks, backyard poultry, backyard pigs, and humans co-occur in time and
space. Some molecular studies in wild ducks and their environment have
been conducted in this Natural Protected Area (Cuevas-Domínguez et al.,
2009; Ornelas-Eusebio, Obregón-Ascencio, Chávez-Maya, &
García-Espinosa, 2015; Ramírez-Martínez, Loza-Rubio, Mosqueda,
González-Garay, & García-Espinosa, 2018). Nevertheless, the aims of
these studies were no centered on the interrelation among diverse
species, and a persistent gap in knowledge about IAV dynamics in the
wildlife – livestock interface remains in the region. Therefore, this
study performed molecular and phylogenetic characterization of IAV in
wild ducks, backyard swine, and backyard poultry at this interface of
Central Mexico.