Hepatitis A virus detection by RT-qPCR in shellfish samples from three Moroccan Atlantic coastal areas: Dakhla, Oualidia, and Moulay Bousselham.

This comparative study assessed hepatitis A virus (HAV) contamination in shellfish harvesting areas in Morocco, and the correlations between viral contamination and rainfall. To this aim, HAV contamination was evaluated in 156 shellfish samples collected at three Moroccan coastal areas (52 samples/area): Dakhla (class A), Oualidia (class B), and Moulay Bousselham (class C). Samples were collected monthly between March 2018 and March 2019, and included oysters from different farms at the Oualidia and Dakhla coastal areas, and wild mussels at the Moulay Bousselham lagoon. HAV was detected by RT-qPCR in 24/156 (15.38%) samples: 16/145 (11.03%) mussel (Mytillus galloprovincialis) and 8/156 (5.13%) oyster (Crassostea gigas) samples. The 16 mussel-positive samples (16/52) were collected at Moulay Bousselham, and the eight oyster-positive samples (8/52) were collected at Oualidia, and none at Dakhla (class A). The highest HAV contamination rate was recorded at Moulay Bousselham lagoon (class C) (30.77%), while it did not exceed 8% at Oualidia (class A). A nonsignificant, positive correlation between HAV-positive samples and mean rainfall was observed. The important HAV presence in bivalve mollusks from the Oualidia and Moulay Bousselham lagoons indicate the need of viral surveillance of bivalve mollusks and of improving wastewater quality to enhance shellfish safety.