Penetration Enzymes of Schistosome Cercariae.

The infective process during which schistosome cercariae invade the skin of vertebrate hosts includes several aspects about which our knowledge is incomplete. These aspects concern changes in the relationship of the cercariae to the snail host in which they developed, in penetrated vertebrate host skin, and in the invading parasite itself. In order better to understand the infective process, data have been accumulated and analyzed under the following headings 1 the infective process - fluctuations in snail-cercaria relations 2 the infective process - the rotifer problem 3 morphological fine structural changes as cercariae transform to schistosomules and 4 antigenicity of secreted cercarial preacetabular enzyme.