Occurrence and Control
E-Book, Englisch, 482 Seiten
ISBN: 978-1-78242-350-8
Verlag: Elsevier Reference Monographs
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)
Provides an overview of the occurrence, transmission, and control of parasites in the food chainExplores the different types of foodborne parasites and the dynamics of parasite transmission in different food sourcesHighlights prevention and control methods to ensure the safety of the food chain
Autoren/Hrsg.
Weitere Infos & Material
1 Introduction to foodborne parasites
A.A. Gajadhar Canadian Food Inspection Agency, Saskatoon, SK, Canada Abstract
Parasites transmitted by food are increasingly recognized as a global threat to food safety and trade. Phylogenetically and biologically, parasites represent one of the most diverse groups of pathogens. Unlike bacteria and viruses, they are typically endowed with structural and functional attributes that facilitate their survival, replication, and transmission in the food web. These characteristics, in addition to the globalization of the food supply, the increasing trend of consuming fresh, ready-to-eat food, the general lack of knowledge of parasites, and the paucity of practical diagnostic and effective control methods have all led to the understanding that foodborne parasites are among the most neglected global pathogens affecting humans. Basic information to inform readers about foodborne parasites is an essential introductory step to understanding the occurrence and control of these parasites and their importance to consumers, the industry, and its regulators. Keywords Food safety Foodborne Parasites Pathogens Neglected diseases Socio-economic impact. 1.1 Introduction
A safe food supply is essential to the survival of humankind. As people have multiplied and technology has advanced, the food supply has evolved from a base of local consumer production to large-scale integrated production and distribution practices. Consumers, particularly those in urban regions, are largely unaware of the origin and processing of their food. Similarly, most producers are unaware of the variety of potential public health hazards that are transmissible by food. Both consumers and producers rely on government regulations and oversight for guidance and protection. Although information regarding foodborne hazards is widely available from many sources, especially regarding hazards such as bacteria and chemical residues, there is limited information on foodborne parasites. This is becoming an urgent matter as the food supply web is now global and expertise in parasitology in developed countries has waned. This complacency has been driven primarily by improved hygiene standards and the increasingly effective control of zoonotic parasites in food animals in those regions. This chapter introduces the diversity and unique characteristics of foodborne parasites, the food vehicles by which they are transmitted, and their significance to consumers. A ranking of these foodborne parasites by various socioeconomic factors and information relevant to their control are presented. The world’s population currently exceeds 7 billion consumers living in regions where foodborne parasites are endemic or where there is risk of infection from imported food. Yet, relatively little is known about parasites, and their identity and characteristics are often confused with those of bacteria and viruses. Parasites are eukaryotic organisms that are classified within diverse taxa ranging from single-cell protozoa to complex hermaphroditic helminths. Foodborne parasites that are prevalent globally or regionally include the flagellated protozoon Giardia, the coccidian protozoa Cryptosporidium and Toxoplasma, the roundworms (nematodes) Trichinella and Anisakis, the tapeworms (cestodes) Taenia and Echinococcus, and the flukes (trematodes) Opisthorchis, Clonorchis, and Fasciola. The diversity of their structural and life-cycle characteristics that are employed in astounding strategies for survival, transmission, host adaptation, and replication makes parasites difficult to control but also fascinating to study. 1.2 Parasites transmitted by food
Human parasitic infections originate from many sources and are acquired by various modes of transmission. Oral transmission via food and water represents the most common route of infection. Because food is produced globally in a wide range of microenvironments, and because it originates from a variety of aquatic or terrestrial animals and plants, there is a diverse range of strategies for parasite survival, replication, and transmission. A list of various food products and examples of the parasites they transmit is provided in Table 1.1. Although many waterborne parasites such as Giardia and Entamoeba have simple, direct life cycles, foodborne parasites often have life cycles that involve multiple stages and various host species that exploit both the exogenous and endogenous environments and food habits of consumers. Generally, meatborne parasites replicate and attain infectivity in protective structures such as cysts within muscle, established during the animal’s development (Table 1.1). Examples include Toxoplasma gondii, Sarcocystis hominis, and Trichinella spiralis. Other parasites such as Giardia and Cryptosporidium can infect consumers by contaminating surfaces of ready-to-eat fruits and vegetables. Table 1.1 Food groups and products that can serve as transmission vehicles for parasites capable of infecting consumers Animals: aquatic Amphibians (frogs) Alaria americana
Spirometra spp. Metacercaria
Plerocercoid Crustaceans (crab, shrimp, etc.) Anisakidae Larva (L3) Paragonimus spp. Metacercaria Freshwater fish Alaria Americana
Clonorchis sinensis Metacercaria
Metacercaria Diphyllobothriidae Plerocercoid Heterophyidae Metacercaria Metrochis spp. Metacercaria Opisthorchis spp. Metacercaria Marine fish Anisakidae Larva (L3) Diphyllobothriidae Plerocercoid Heterophyidae (brackish water) Metacercaria Shellfish Cryptosporidium spp. Oocyst Giardia duodenalis Cyst Toxoplasma gondii Oocyst Animals: terrestrial Beef Sarcocystis hominis Tissue cyst Taenia saginata Cysticercus Toxoplasma gondii Tissue cyst Dairy products Toxoplasma gondii Tachyzoite Cryptosporidium spp. Oocyst Game meat Alaria americanum
Toxoplasma gondii Metacercaria
Tissue cyst Trichinella spp. Larva (L1) Horse Toxoplasma gondii
Trichinella spp. Tissue cystLarva (L1) Pork Paragonimus spp.
Sarcocystis suihominis Metacercaria
Tissue cyst Taenia solium Cysticercus Toxoplasma gondii Tissue cyst Trichinella spp. Larva (L1) Reptiles Alaria Americana
Spirometra spp.
Trichinella spp. Metacercaria
Plerocercoid
Larva (L1) Small ruminants Toxoplasma gondii Tissue cyst Snake Spirometra spp. Plerocercoid Animals: birds Chicken Toxoplasma gondii Tissue cyst Water fowl (geese, ducks) Toxoplasma gondii Tissue cyst Plants: aquatic Fresh produce Fasciola spp. Metacercaria Fasciolopsis buski Metacercaria Plants: terrestrial Fresh produce (berries, leafy greens, etc.) Ascaris spp. Egg Balantidium coli Cyst Cryptosporidium spp. Oocyst Cyclospora cayetanensis Oocyst Echinococcus granulosus Egg Echinococcus multilocularis Egg Entamoeba histolytica Cyst Giardia duodenalis Cyst Taenia solium Egg Toxocara...
