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DIN Standards Committee Food and Agricultural Products

Overview

Cryptosporidium spp. and Giardia duodenalis (syn. G. lamblia, G. intestinalis) are protozoan parasites that can cause enteric illness in humans. Both organisms are characterized by a robust transmission stage, the Cryptosporidium oocyst and the Giardia cyst, which can survive for extended periods in most environments (desiccation has a killing effect). Since these transmission stages (referred to as oocysts), are highly resistant to chemical and physical processes, including chlorine at concentrations used to treat drinking water, and to disinfectants used on produce, the absence of vegetative bacteria on fresh produce as indicators of fecal contamination does not necessarily indicate the absence of oocysts. No practical method exists to culture Cryptosporidium spp. and Giardia duodenalis for the purpose of detection, and therefore, in order to detect contamination with these parasites, direct removal of the (oo)cysts from the food sample must be performed, followed by visualization of the (oo)cysts by microscopy. This International Standard specifies a method that is applicable for the detection and enumeration of Cryptosporidium oocysts and Giardia cysts on or in food products that are described herein as fresh leafy green vegetables and berry fruits. With suitable controls, it may also be applicable for the examination of other fresh produce. The method serves the purpose of consumer health protection. The microscopy descriptions are for Cryptosporidium spp. oocysts and Giardia duodenalis cysts of size ranges which include those species (Cryptosporidium) or assemblages (Giardia) known to be pathogenic to humans. not suitable for the determination of the species or genotypes/assemblages of Cryptosporidium oocysts and Giardia cysts. The method will detect all species and genotypes/assemblages that are known to be pathogenic for humans and also others that are not. For further identification, molecular typing assays are required. However, these cannot be reliably performed if process positive controls have been spiked into the samples, as the result of molecular typing assays will be obfuscated. This method does not allow the determination of viability or infectivity of any Cryptosporidium oocysts and Giardia cysts which may be present. The committee responsible for this standard is NA 057-01-06 AA "Mikrobiologische Lebensmitteluntersuchung einschließlich Schnellverfahren" ("Microbiological analysis of foodstuffs including rapid method") at DIN.

Document: references other documents

Responsible national committee

NA 057-01-06-03 AK - Parasites  

Responsible european committee

CEN/TC 463 - Microbiology of the food chain