Which factor contributed to surveillance challenges during the 2015 HPAI outbreak due to movement via wild waterfowl?

• A. Rapid detection in domestic poultry only
• B. There was no need for depopulation
• C. Carrier state in wild waterfowl hindered surveillance
• D. Domestic poultry farms had robust biosecurity

Answer: (C)

Asymptomatic carriage in wild waterfowl is the key factor. Wild ducks, geese, and other waterfowl can harbor avian influenza and shed the virus without showing illness, so they move long distances during migration while remaining seemingly healthy. This silent carriage enables the virus to be carried along flyways and introduced into new regions well before detection, making surveillance across wildlife and poultry difficult. During the 2015 HPAI outbreak, the clear warning signs weren’t always present in wild populations, so early detection lagged because surveillance programs tend to emphasize domestic flocks or visibly sick/dead wildlife rather than testing healthy wild birds. The result is a gap between virus movement through wildlife and the ability of authorities to trace and contain it, which is why the carrier state in wild waterfowl best explains the surveillance challenges in this outbreak.