A novel Salifa–Saprolegnia association

During the period from December 2006 to March 2007, about 1000 freshwater leeches, Salifa delicata, were collected from Al-sont canal, adjacent to Assiut city, Egypt. In the laboratory, 96% of Salifa delicata showed signs of oomycotal infection (cotton–wool like appearance radiating out in whorled pattern) and died within 3 days. Direct microscopy and culture proved Saprolegnia hypogyna to be the pathogen. Histopathological studies showed necrotic lesions, destruction of cuticle, epidermis, dermis, muscle layers, botryoidal tissue and even the gut with the oomycete hyphae penetrating the damaged tissues. To the best of the authors’ knowledge, this represents the first record of a novel association between the leech, Salifa delicata, and the oomycete, Saprolegnia hypogyna, but the second report on the histopathology of saprolegniasis within leeches.