New data on Perkinsus mediterraneus in the Balearic Archipelago: locations and affected species

Perkinsus spp. Occurrence in South America: A review

Marine mollusk production is increasing worldwide, and this trend is being evidenced in South American countries, where several species of bivalves are produced, exploited, and traded. This activity brings benefits either for the ecosystem, as it is a less impactful and polluting than other aquaculture practices, and to coastal human communities, as it provides food and income. However, emergence of outbreaks by pathogens is a major concern and can put an entire developing sector at risk. Perkinsosis is a disease caused by Perkinsus spp. protozoans that affect mollusks worldwide. In this review we provide information on Perkinsus spp. among bivalves from South America. Infections by these parasites were only reported to date among coastal Atlantic bivalves of Argentina, Uruguay, and Brazil. The vast majority of cases and studies are reported from Brazil. We comprehensively review those results here. Finally, we suggest some considerations for future investigations that may expand our knowledge of these parasites.

Development and validation of a specific real-time PCR assay for the detection of the parasite Perkinsus olseni

Perkinsus olseni is a protozoan parasite that infects a wide variety of molluscs worldwide, causing economic losses in the aquaculture sector. In the present study, a quantitative PCR (qPCR) assay was developed for the detection and quantification of P. olseni in clam gill tissue and hemolymph (Ruditapes philippinarum and R. decussatus), and the results were compared with those of the standard diagnostic methods recommended by the O.I.E. (World Organisation for Animal Health): Ray's fluid thioglycollate culture method (RFTM), a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay and histopathology. The efficiency, sensitivity and reproducibility of the newly described qPCR assay were also determined. The highest prevalence was detected using the qPCR assay, and the strongest linear correlation was obtained between the RFTM infection levels and the threshold cycle (Ct) number from the gill tissue. Although better results were obtained from gill than from the hemolymph in the qPCR assays, especially with lower infection levels of the parasite, a significant linear correlation was observed between Ct values from the gill and hemolymph. The qPCR assay that was developed in this study showed high sensitivity, specificity and reproducibility for the detection and quantification of P. olseni.