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Hundreds of millions of people, particularly those who live in rural areas or deprived urban settings in the developing world, are at risk of acquiring foodborne trematodiasis and schistosomiasis.1-3

Foodborne trematodiasis include clonorchiasis, paragonimiasis, fascioliasis, and opisthorchiasis. These and schistosomiasis all belong to the subclass of Digenea, class of Trematoda, phylum of Platyhelminthes. The taxonomy of Platyhelminthes is shown in eFigure 335.1. Digeneans, also known as flatworms, are characterized by dorsoventral flattening, presence of an oral sucker and often a ventral sucker, and lack of a circulatory system.4Figure 335-1 shows, by means of scanning electron microscopy, the head portion of an adult Clonorchis sinensis (a liver fluke), clearly depicting some of the typical features of the Digeneans.

eFigure 335.1.

Taxonomy of Platyhelminthes.

Figure 335-1.

Scanning electron microscopic image of the head portion of an adult Clonorchis sinensis fluke (OS, oral sucker; VS, ventral sucker).


The endemic regions of the world, global burden and at risk populations for infection with clonorchiasis, fascioliasis, fasciolopsiasis, opisthorchiasis, paragonimiasis, and schistosomiasis are summarized in Table 335-1.3,5-10

Table 335-1. Schistosomiasis and Foodborne Trematodiasis

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