Fecal examination. The presence and the intensity of OV infection were determined by FECT with slight modification from the previous protocol [4, 5] as described below. Briefly, two grams of fresh feces were transferred from the sample into a tube containing 7 mL of 10% formalin. The samples were thoroughly homogenized and strained through two layers of gauze into the 15 mL centrifuge tube. The strained suspension was centrifuged at 2,500 rpm for 5 min and the supernatant was poured out. Ten mL of 0.85% saline were added to the tube and then mixed, followed by the addition of 3 mL of ethyl acetate to aid in the extraction of fat from the stool. The suspension was then centrifuged at 2,500 rpm for 5 min and resulted sediment was fixed with 1 mL of 10% formalin. The final fecal suspension was examined two time per sample by the same microscopist using a compound microscope at 40X with the results combined to calculate the number of eggs per gram of feces (EPG).