Exo-alpha-sialidase that catalyzes the hydrolytic cleavage of the terminal sialic acid (N-acetylneuraminic acid, Neu5Ac) of a glycan moiety in the catabolism of glycolipids, glycoproteins and oligosacharides. Efficiently hydrolyzes gangliosides including alpha-(2->3)-sialylated GD1a and GM3 and alpha-(2->8)-sialylated GD3. Hydrolyzes poly-alpha-(2->8)-sialylated neural cell adhesion molecule NCAM1 likely at growth cones, suppressing neurite outgrowth in hippocampal neurons. May desialylate sialyl Lewis A and X antigens at the cell surface, down-regulating these glycan epitopes recognized by SELE/E selectin in the initiation of cell adhesion and extravasation. Has sialidase activity toward mucin, fetuin and sialyllactose.