Foodborne Trematodiases

Foodborne trematodiases is a neglected tropical disease affects at least 56 million people in the world, who live in lesser developed countries. There are four types of Foodborne trematode infections: Clonorchiasis, Fascioliasis, Opisthorchiasis, and Paragonimiasis. People can become infected by consuming raw fish, vegetables, or other kinds of food that contain the parasite larvae. They are most prevalent in East Asia and South America. The result of contracting these infections are severe liver and lung diseases. There are medicines available to combat these diseases.


All types of Foodborne trematode infections are helminthic. Which means that they are infections that are caused by worms entering the human the human body. These types of worms are trematodes, which means that are flat worms.  

Table 1. Epidemiological characteristics of foodborne trematodiases
Disease Infectious agent Acquired through consumption of Natural final hosts of the infection
Clonorchiasis Clonorchis sinensis Fish Dogs and other fish-eating carnivores
Opisthorchiasis Opisthorchis viverrini,

O. felineus

Fish Cats and other fish-eating carnivores
Fascioliasis Fasciola hepatica,

F. gigantica

Aquatic vegetables Sheep, cattle and other herbivores
Paragonimiasis Paragonimus spp. Crustaceans (crabs and crayfish) Cats, dogs and other crustacean-eating carnivores

The table from the WHO shows the different forms and their infectious agents.


Clonorchiasis, raw fish infection.

Opisthorchiasis, raw fish infection.


Paragonimiasis, infection from Crustaceans. 



The hosts of all of these are both humans and animals. However, the cycle for all of these diseases begin with a freshwater snail. Later, the second hosts for clonorchiasis and opisthorchiasis are freshwater fish, the hosts for paragonimiasis are crustaceans, and fascioliasis does not require a second intermediate host — but sheep, cattle, and other herbivores have all known to be hosts of it. For all four of these infections, the final host is always a mammal, many times a human. Humans become infected when they consume the second intermediate host that contain larval forms of the infection. However, in the case of fascioliasis, when the larvae is consumed along with the aquatic vegetables that they are attached to is the way humans become infected.

Transmission cycle of the infections. echinococcus_lifecycle


The different locations where the four different infections are endemic reflect the region and the kinds of foods they take in and domestic animals they have, among other factors.

Locations of where the most infections happen around the world.

Symptoms and Prevention

The four infections all cause some kinds of symptoms, some in similar ways and in some different ways. For clonorchiasis and opisthorchiasis, adult worms lodge themselves inside the smaller bile ducts inside the liver. This causes inflammation and fibrosis in the surrounding tissues, this causes cholangiocarcinoma which is a fatal king of bile duct cancer. In fascioliasis, adult worms lodge themselves in the larger bile ducts of the liver, and in the gall bladder. This causes inflammation, fibrosis, blockages, colic pains and jaundice. Sometimes, liver fibrosis and anaemia occur. In paragonimiasis, the worms end up in the lung tissue. Here, they cause tuberculosis. Sometimes, these worms can move, the most severe locations they can migrate to are parts of the brain.

These infections can be prevented by using drugs that can expel the worms from the body. Also, treating food correctly and carefully during preparation.

Screen Shot 2017-02-09 at 7.26.05 PM.png

Table from the WHO on treatment.

All information taken from the WHO and the CDC


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