Food-Borne Trematodiases

Abstract

SUMMARY An estimated 750 million people are at risk of infections with food-borne trematodes, which comprise liver flukes (Clonorchis sinensis, Fasciola gigantica, Fasciola hepatica, Opisthorchis felineus, and Opisthorchis viverrini), lung flukes (Paragonimus spp.), and intestinal flukes (e.g., Echinostoma spp., Fasciolopsis buski, and the heterophyids). Food-borne trematodiases pose a significant public health and economic problem, yet these diseases are often neglected. In this review, we summarize the taxonomy, morphology, and life cycle of food-borne trematodes. Estimates of the at-risk population and number of infections, geographic distribution, history, and ecological features of the major food-borne trematodes are reviewed. We summarize clinical manifestations, patterns of infection, and current means of diagnosis, treatment, and other control options. The changing epidemiological pattern and the rapid growth of aquaculture and food distribution networks are highlighted, as these developments might be associated with an elevated risk of transmission of food-borne trematodiases. Current research needs are emphasized.

Human liver flukes

“…Splenomegaly is a rare finding (23) . Acute symptoms seem to occur more frequently in O. felineus infections than in C. sinensis and O. viverrini, and fever is sometimes seen (7) .…”

“…An estimated 10 million people are infected worldwide, 80% of whom reside in Thailand (7) . A study in Thailand showed O. viverrini infection rates ranging between 2 and 71% in different districts (15) .…”

“…It has a worldwide distribution and is a common zoonosis throughout Eurasia and parts of South America and Africa (5) . Previous estimates suggest between 2·4 and 17.0 million people are infected worldwide (7) . Cattle and sheep herders are at higher risk and, in endemic areas, infection is more common in children (5) .…”

“…Fasciola cercariae encyst (as metacercariae) on aquatic vegetation such as the watercress, water lotus, water caltrop, water chestnut, or water lily (7) and infection of the definitive or incidental (human) host is acquired from eating contaminated plants. Dandelion leaves, lettuce, spearmint, algae, corncob, alfalfa, spinach, broccoli, morning glory have also been described as vectors in human infection (5,7) . Metecercariae are also found on water surfaces, and use of contaminated water for drinking, or washing food or kitchen utensils may result in human infection (7) .…”

“…Dandelion leaves, lettuce, spearmint, algae, corncob, alfalfa, spinach, broccoli, morning glory have also been described as vectors in human infection (5,7) . Metecercariae are also found on water surfaces, and use of contaminated water for drinking, or washing food or kitchen utensils may result in human infection (7) . Outbreaks have also been seen in chewers of Khat, a narcotic leaf which may become contaminated by water used to keep it fresh during transport (8) .…”