Oocyst Counting

The number of oocysts per gram (OPG) of faecal samples were counted on days 19 to 28 (5–14 D postinnoculation [PI]), by using the modified McMaster counting chamber technique of Hodgson (1970). The faecal samples were kept in separate airtight plastic bags. A suspension of 10% (w/v) faeces in saturated salt solution was prepared. The samples were shaken, and 1 mL of the suspension was mixed with 9 mL of saturated salt solution. Specific amount of the suspension was put on the McMaster chamber, and the number of the oocysts was counted under 10× magnitude using a light microscope (Peek and Landman, 2003).