EXCYSTATION RATES AND INFECTIVITY OF SPOROCYSTS OF SARCOCYSTIS-CRUZI EXPOSED TO DIFFERENT TREATMENTS AND STORAGES

The effect of some chemical and anatomical factors on the excystabilit y and infectivity in cell culture of sporocysts of Sarcocystis cruzi w as investigated. A significantly (P < 0.001) higher excystation rate ( ER) occurred when sodium bicarbonate was added to the excysting fluid at concentrations between 0.075 and 0.3 M. Sporocysts collected from d ifferent dogs had different ER. In contrast, although not uniformly di stributed along the intestinal lumen, the sporocysts collected from th e different tracts of the intestine showed similar ER. The period of s torage did not affect the excystability of the sporocysts; howe ver, i t influenced the pattern of growth of the sporozoites in cell culture. Sporozoites excysted from sporocysts stored for approximately 2 years grew slower and produced significantly fewer merozoites compared to t hose excysted from sporocysts stored for 5-7 months. (C) 1997 Elsevier Science B.V.