*2.1. Sample Collection*

Chicken (*n* = 152) and duck (*n* = 154) carcasses were purchased from 18 wet markets throughout Korea during the summer (June–August, in 2014) and winter seasons (December in 2014 to February in 2015) (Figure 1). Three to ten samples for both chicken and duck carcasses were collected per market and per visit, and each market was visited twice for summer and winter. The samples were placed in a cooler on ice and transported to a laboratory. They were analyzed within 24 h.

**Figure 1.** The locations of wet markets for poultry samples collected in Korea.
