. At each sampling point, 25 g of sample was added to 225 mL of sterile 0.1% peptone water and stomached (Seward 400) for 1 min at 260 strokes per min. Serial dilutions were prepared using 0.1% peptone water, and 100 μl aliquot plated onto Salmonella-Shigella agar (Acumedia) in duplicate. Colonies were counted after 36–48 h incubation at 35 °C