Identification of Schistosoma mansoni, S. rodhaini, S. bovis, S. haematobium, and S. intercalatum cercariae using segmentation analysis.

Cercariae of five species of schistosomes identified with certainty were fixed in boiled alcohol and mounted in glycerol-alcohol mixture. The cercarian body (Cbl) and tail-furcae lengths (Ctl) were measured, the values of which were treated using a computer. Even mean values allowed partly identification of the present species, the segmentation analysis gave better informations for separating any cercaria taken at random, with a given probability (p). Thus, five classes (A, B, C, D, E) have been established: class A: Cbl > 139 microns and Ctl, > 236 microns, p = 0.59 to be considered as S. bovis; class B: Cbl > 139 and Ctl < 236, p = 0.86 to be considered as S. haematobium; class C; Cbl < 114 microns, p = 0.75 to be considered as S. intercalatum; class D: 114 < Cbl < 125 microns, p = 0.57 to be considered as S. mansoni; class E: 125 < Cbl < 139 microns, p = 0.57 to be considered as S. rodhaini. Two groups of schistosome have been established on basis of cercarian morphometry with S. intercalatum, S. mansoni and S. rodhaini from one side, S. haematobium and S. bovis to the other side.