TABLE 1.

Summarized applicability of environmental sampling as compared to live bird sampling in the surveillance of avian influenza viruses

Environmental sampling	Live bird sampling (cloacal or oropharyngeal swab)
Flexible; easy to adapt sample size, timing, frequency, location, and can be applied across value and supply chains and in a number of contexts (Jennelle et al., 2016; Pannwitz et al., 2009)	Less flexible; contingent on presence and number of birds (live, hunter‐killed birds, post‐mortality events or otherwise) when wild bird sampling
Acceptable to traders and stall vendors in live bird markets (Indriani et al., 2010; Vergne et al., 2019; Zeynalova, Guliyev, Vatani, & Abbasov, 2015)	Potential for reduced willingness of persons in live bird markets (traders, stall vendors, etc.) to participate due to perceived disruption of business operations, trading and selling activities (Bui et al., 2019; Indriani et al., 2010)
Cost‐effective; simple and rapid procedure, minimal training, equipment required, and easily scalable to increase sample size at minimal cost (Deliberto et al., 2009; Deliberto et al., 2009; Gaidet et al., 2007; Grillo et al., 2015; Grillo et al., 2015; Lebarbenchon et al., 2010; McLean et al., 2007; Onuma et al., 2017; Pannwitz et al., 2009; Pannwitz et al., 2009; Stallknecht et al., 2012; Tracey, 2010)	Additional financial, technical, and logistical implications associated with bird trapping or capture and invasive and labour‐ and time‐intensive sample (oropharyngeal, cloacal, blood) collection (Pawar et al., 2012; Tracey, 2010)
Bird welfare; does not require trapping, capture or handling of birds (Bui et al., 2019; Zeynalova et al., 2015)	Requires stressful trapping or capture and handling of birds, invasive sampling procedures, disruption of wild bird communities (Pannwitz et al., 2009)
Safer; reduced potential for virus aerosolization) (Indriani et al., 2010; Zeynalova et al., 2015)	Risk of virus aerosolization and infection for sample collectors and bystanders (Indriani et al., 2010)
Loss of individual‐level data (for example, host species, host age, host condition)	Allows for the collection of individual‐level data, and corresponding epidemiological analyses
Markets: Smaller number of samples required to detect virus if sites recognized to be highly contaminated are sampled	Large number of samples required to detect virus if present at low prevalence.
Positive result may reflect infection in birds at an earlier time depending on type of sample collected	Represents situation in birds at the time of sample collection