Efficacy of commercial cleansing procedures in eliminating Cryptosporidium parvum oocysts from bivalves.

SHELLFISH is one of the most important aquaculture products of Portugal yielding approximately 5,000 tons/yr (Direcção Geral das Pescas, www.dg-pescas.pt, July 2006). Seafood is an excellent natural resource which is common in the Portuguese diet and is in high demand by tourists. Some shellfish are consumed raw or undercooked. Several legal regulatory steps are in place that control processes from production to sale to ensure consumption of uncontaminated live bivalves (Diário da República, Decreto-Lei #293/98, 18 September; Despacho extracto #18 940/ 2005, 2 série, 12 July). According to Portuguese law, the location and classification of bivalve production areas are based on several criteria such as indicators of bacterial contamination. However, parasite indicators are not currently evaluated. Bivalves from production areas classified as A do not need further cleansing. Those collected from B areas can only be eaten if they undergo a cleansing procedure before commercialization. If collected from C areas, intense cleansing or cooking in industrial factories is required before human consumption. The environmental quality of the collection sites vary according to the effectiveness of sewage treatment in rural areas and to discharge centers in urban areas of the country. Cryptosporidum parvum is an enteric zoonotic parasite that is often discharged into rivers and seas by rain and sewage treatment effluents. Bivalves can concentrate oocysts in their gills and digestive glands during feeding, thus the aim of this study was to evaluate the efficiency of the process for removing bacteria from commercial bivalves in removing Cryptosporidium from bivalves consumed in Portugal.