Must be centrifuged at 7000 g for 10 minutes, Trypomastigotes of Trypanosoma cruzi, Trypanosoma brucei rhodesiense, Trypanosoma brucei gambiense Trophozoites of Naegleria and Parastrongylus larvae must be within 20 minutes since trypomastigotes perish and the morphology and motility of Naegleria trophozoites are affected within the time period