SPEED OF SKIN PENETRATION AND INITIAL MIGRATION ROUTE OF INFECTIVE LARVAE OF SCHISTOSOMA-HAEMATOBIUM IN MERIONES-UNGUICULATUS

The kinetics of skin penetration of Schistosoma haematobium (Bilharz, 1852) (Trematoda, Schistosomdtidae) cercariae is reported for the firs t time, Meriones unguiculatus (Rodent, Gerbillidae) being used as expe rimental model. It has been demonstrated that the cercariae a cross th e epidermis of their hosts either directly or through hair follicles c uls-de-sac from 3 to 5 min. The corresponding schistosomulae slide int o the superficial part of the dermis or move along the base of hair fo llicles. Six minutes after, schistosomulae are found in the lumen of l ymphatic vessels running alongside blood capillaries. One hour post-in festation, the dermis presents acute inflammatory reaction with edema, infiltration of neutrophil and eosinophil leukocytes. Conversely, dil ated blood capillaries do not contain any schistosomula. Thus, the ini tial migration path of infective larvae of S. haematobium in M. unguic ulatus is lymphatic.