Intestinal Flukes

Food-borne intestinal flukes are highly diversified, consisting of at least 74 species with diverse global distribution. Taxonomically, they include 28 species of heterophyids, 23 species of echinostomes, and 23 species of miscellaneous groups (Chai and Jung 2020). Of the intestinal flukes, Fasciolopsis buski is the most common, followed by Heterophyes heterophyes, Metagonimus yokogawai, and Echinostoma ilocanum. Gastrodiscoides hominis, Phaneropsolus bonnei, and Prosthodendrium molenkampi rarely cause human intestinal infections ( http://emedicine.medscape.com/article/219662-overview ). More than 70 species of fish, including both freshwater and marine species, are intermediate hosts susceptible to invasion by metacercariae and can thus potentially infect food. These are a variety of freshwater and brackish-water fish and snails, reptiles (amphibians and certain snakes), aquatic plants, and insects. There is a wide variety of reservoir hosts for these flukes, including fish-eating birds and wild and domestic mammals, especially cats, dogs, and pigs. Human fondness for raw or lightly prepared fish foods is the primary human risk factor and is responsible for the wide geographical distribution of human infections. An estimated 40–50 million people get infected by intestinal flukes, and nearly 600 million are at risk the world over, especially in Asia and also in Europe, Africa, the Near East, and North and South America (FAO/WHO 2014).