Adhesion of Cercaria (Larva of Helminth Parasites) to Host by Lectins- carbohydrates bonds as a Model for Evaluation of Schistosoma Entrance Mechanisms in Cercarial Dermatitis

Abstract

Background: Cercariae (larva of helminth parasites) are covered by a thick glycocalyx coat, which serves as an osmotic pro­tection during their free existence, and contain carbohydrates conjugated as glycoproteins, glycolipids and mu­co­polysaccharides. Although, limited studies have been made on life cycle of cercariae from fresh water snails, however, car­bo­hydrate studies on cercariae have not been done in Iran so far. This study was made to determine the cercariae speci­fica­tions from Lymnaea gedrosiana and evaluation of surface carbohydrates as receptors for host lectins in a host-parasite rela­tionship system as a model in human schistosomiasis including cercarial dermatitis in Khuzestan Province.

Methods: For this purpose, snails were collected from Dezful region in Khuzestan Province and cercariae were obtained by shed­ding method and identified by valuable keys. Experimental infection was established in the Culex pipiens (Culicidae mos­quitoes) larvae for further identification and mode of adhesion. To detect the mode of adhesion, surface carbohydrates of cercariae were detected by lentil (Lens culinaris) lectins.

Results: Examined snails were infected with xiphidiocerceria of trematodes and metacercariae were obtained from Culex pipiens. Also, Mannose monosaccharides- CH2OH (CHOH) 4CHO - were detected particularly on the glands of cercariae.

Conclusion: Adhesion of cercariae to their host by lectins-carbohydrates bonds is the first stage of host-parasite relation­ship. This phenomenon could be happened for animal schistosome's cercaria in cercarial dermatitis.