A PCR-Based Assay for Detection of Hematodinium sp. in Sediment and Water from the Maryland Coastal Bays

Hematodinium sp. is a parasitic dinoflagellate that infects the blue crab Callinectes sapidus and other crustaceans of economic importance. Using real-time PCR based methodology, we can now detect Hematodinium parasites in various crab tissues down to as little as 10 parasites per sampled tissue. This method will enable us to understand infection progress through the parasitic life cycle. One important question that remains is to understand the mode of initial parasite infection. Crab-to-crab direct transmission has been posited as one likely route. We also sought to discover a potential environmental reservoir through analysis of various ecological sites within the Maryland Coastal Bays, as transmission through dinospores has been posited as one potential mode of transmission. Sediment samples were collected and analyzed using primers that are specific to the Internal Transcribe Spacer region of  Hematodinium sp. We report here the discovery of  Hematodinium DNA in sediment from the junction between northern Chincoteague Bay and southern Newport Bay. This Q-PCR result was confirmed through direct cloning of a PCR fragment and comparison with genomic sequence deposited within Genbank.  Ongoing studies will seek to confirm this result, and to further understand the biological and environmental factors related to this potential “hot spot” for a putative mode of disease transmission.