Adenovirus detection in shellfish and urban sewage in Morocco (Casablanca region) by the polymerase chain reaction.

Human enteric viruses are largely excreted in faeces. These resistance of these viruses in the environment makes their faecal-oral transmission easier. Filter feeder organisms such as the mussels are bio-accumulators of viruses contaminating their aquatic environment. Thus, undercooked shellfish consumption involves sanitary risks. Thirty samples of mussels (Mytilus sp.), were tested, half were from an aquaculture origin, the others were from an area more exposed to faecal pollution. Fifteen sewage samples from this last area were also examined. Viruses were extracted from the digestive tissue by direct elution method in a glycine/NaCl pH 9.5 buffer followed by PEG 8000 precipitation. The PEG pellets were used for DNA extraction by proteinase K and phenol/chloroform. The molecular characterization, by PCR using specific adenovirus primers revealed that shellfish growing on Mohammedia (a town in the Casablanca outskirts) littoral are contaminated whereas those chosen from aquaculture and bought in the central market were not contaminated.