Coexistence of two species of haplosporidian parasites in a population of the marine amphipod Parhyale hawaiensis with evidence for parasite phagocytosis and transmission mode.

The amphipod parhyale hawaiensis live hiding underneath stones and shingles along the shore line in supra-littoral zone of sharm el-nagha site,hurghada city,red sea. the collected specimens of p. hawaiensis are infected with two protozoan parasites,urosporidium sp. and haplosporidium sp. which invade many organs of both females and males. the life cycle of the parasites was described in addition to their histopathological effects on host's tissues. the study showed some evidence for the defense reaction of the host as engulfing and degraded stages of parasites by granulocytes. the two parasite species coexist at different prevalence's in one host population and bi-infected individuals were few.