Avian Influenza Virus Surveillance in South-Central Spain Using Fecal Samples of Aquatic Birds Foraging at Landfills

Abstract

Aquatic wild birds have been intensively studied to better understand their role in avian influenza virus (AIV) maintenance and spread. To date, AIV surveillance has primarily focused on natural aquatic environments where different bird species aggregate and viral survival is enhanced. However, artificial habitats such as landfills are attracting substantial numbers of wild birds, AIV reservoir species included. The use of landfills as a predictable food source has significantly influenced population size, migratory traits, and feeding behavior of white storks (Ciconia ciconia) and black-headed gulls (Chroicocephalus ridibundus) among others. Considering the proximity of landfills to urban settlements and frequently poultry-farms, targeted monitoring of AIV in bird species that forage at landfills but are known to also frequent urban and agricultural habitats could be a useful means for monitoring of AIV, especially during periods of bird aggregation. During the wintering season 2014–2015, the prevalence of AIV in five avian species at two landfills in South-Central Spain was explored by rRT-PCR and species related temporal variation in AIV prevalence determined. We collected and tested 1,186 fresh fecal samples from white storks (N = 689), cattle egrets (Bubulcus ibis, N = 116) and mixed flocks of gulls (N = 381) as well as cloacal and oral swabs from five birds found dead. Seven samples contained AIV, five from gulls and one each from a stork and a cattle egret. Overall, AIV prevalence was 0.60%. No significant temporal variation was observed in AIV prevalence. Prevalence differed significantly among the sampled taxonomic groups, being highest in gulls (1.31%). H16N3 subtype was detected from a cattle egret and H11N9 subtype from a white stork, whereas gulls harbored both subtypes in addition to H11N3 subtype. H16 subtype detection in a cattle egret evidences its host range may not be restricted to gulls. Our results indicate that wild birds foraging at landfills may carry different LPAIV subtypes.

A Review of Avian Influenza A Virus Associations in Synanthropic Birds

“…While these studies suggest at least a low-level prevalence of IAVs in cattle egrets in the wild, we only found one experimental study that evaluated infection dynamics. In that study [ 31 ], six cattle egrets were experimentally inoculated with an HP H5N1 virus. While all individuals were highly susceptible and either died or were euthanized, only a low level of viral RNA shedding was observed, and none of the five contact chickens became infected.…”

A literature review of the use of environmental sampling in the surveillance of avian influenza viruses

“…ES was found to be comparable to that of LBS in several contexts (Grillo et al, 2015;Pannwitz et al, 2009;Vergne et al, 2019), while less sensitive in others Mellor et al, 2018;Sonnberg et al, 2012;Tracey, 2010). Furthermore, the use of environmental faecal sampling in the surveillance of LPAIV is well supported by the literature (Baek et al, 2010;Barbara et al, 2017;Gaidet et al, 2007;Lebarbenchon et al, 2010;Perez-Ramirez et al, 2010). In particular, when fresh faecal samples were collected immediately, they were found to have similar (Perez-Ramirez et al, 2010) or higher detection rates than oropharyngeal swabs (Busquets et al, 2010) and cloacal swabs (Chen et al, 2014;Latorre-Margalef, Avril, Tolf, Olsen, & Waldenstrom, 2016).…”

“…Several other examples highlight the effectiveness of ES used either on its own (for low pathogenic AIV (LPAIV)) in wild bird surveillance (Baek et al., 2010; Barbara et al., 2017; Perez‐Ramirez, Gerrikagoitia, Barral, & Hofle, 2010; Piaggio et al., 2012), or as a component (for HPAIV) (Bevins et al., 2014; Haynes et al., 2009; Khan et al., 2018) of large‐scale risk‐based surveillance systems in both high‐ (Deliberto et al., 2009; Grillo et al., 2015; Piaggio et al., 2012; Preskenis, Ladman, & Gelb, 2017) and low‐resourced (Gaidet et al., 2007; Gerloff et al., 2014; Khan et al., 2018; Ofula et al., 2013; Tun Win et al., 2017) settings, where broad‐scale surveillance proves logistically challenging (Grillo et al., 2015).…”

“…Various limitations of ES methods in wild bird surveillance were also identified in the literature. ES may potentially result in the loss of species‐specific information on the virus shedding source, limiting its utility in taxonomic‐level analyses (Barbara et al., 2017; Grillo et al., 2015; Pannwitz et al., 2009). However, this potential disadvantage has largely been overcome, with studies utilizing fresh faecal samples mitigating this through the use of mitochondrial DNA barcoding for host bird species identification (Ge, Chai, et al, 2017; Kang et al., 2010, 2011; Lee et al., 2010; Onuma et al., 2017), collecting samples from single species flocks (Ghersi et al., 2009; Kou et al., 2009; Pawar et al., 2012), through the observation and species identification of the individual host immediately prior to defecation and sample collection (Ge, Chai, et al, 2017; Haynes et al., 2009; Kang et al., 2010; Pannwitz et al., 2009; Ye et al., 2016) and/or by observation of faecal morphology (Ge, Chai, et al, 2017; Ge, Yao, et al, 2017; Hansbro et al., 2010; Pannwitz et al., 2009; Ye et al., 2016).…”

“…(47/327) (Terregino et al, 2007), 28% (214/759) (Piaggio et al, 2012), 43.4% (153/352) (Onuma et al, 2017) up to 66.67% (4/6) (Barbara et al, 2017) among RT-PCR-positive environmental samples. It is noteworthy that when ES with high virus content (CT values < 30) were cultured the rate of isolation was high (Horm et al, 2016).…”