Eurytrema pancreaticum is a trematode flatworm with sheep, goats and pigs as major final hosts. It affects also camels and donkeys, occasionally cattle and also humans. It does not affect dogs or cats.
It is found in Asia and South America. Prevalence varies on local conditions: prevalence can be high in endemic regions.
Other less abundant related species are Eurytrema coelomaticum and Eurytrema ovis.
The disease caused by Eurytrema pancreaticum is called eurytrematosis.
Are animals infected with Eurytrema pancreaticum contagious for humans?
NO. If livestock is infected with pancreas flukes, they are not directly contagious for humans, neither through contact, nor when consuming meat, milk or blood of contaminated animals, nor through the feces. Humans become infected through accidental ingestion of infected locusts (see below under life cycle), not by ingesting adult flukes or their eggs.
Final location of Eurytrema pancreaticum
Predilection site of pancreas flukes are the pancreatic ducts. Occasionally it is found also in the bile ducts and in the small intestine.
Anatomy of Eurytrema pancreaticum
Adult Eurytrema pancreaticum has the flat body and the oval shape typical for most flukes. It is smaller than liver flukes, ~16 mm long and ~8 mm wide. It has 2 prominent suckers, the oral sucker and the larger ventral sucker. As other flukes they have no external signs of segmentation. The mouth ends in the pharynx, a muscular tube that allows sucking. The digestive system is blind (i.e. without anus: the only opening is the mouth) and not linear, as in most animals, but branched, ending in several blind ducts (called coeca). Pancreas flukes are simultaneous hermaphrodites, i.e. they have both male and female reproductive organs.
The eggs have an oval shape and are quite small (~30x45 micrometers) and operculated (i.e. with a cap-like cover).
Eurytrema pancreaticum has an indirect life cycle with two intermediate hosts. The first intermediate host is always a terrestrial snail of various species (e.g. Bradybaena spp, Cathaica spp.). Several locust (e.g. Conocephalus spp) species act as second intermediate host.
The eggs of infected animals leave the final host through its feces. The vector snails become infected in the environment and produce cercariae through two generations of sporocysts. Mature cercariae leave the snails and are ingested by the locusts where they continue development to metacercariae. The final hosts, (typically sheep, goats and pigs) become infected after eating the locusts while grazing. Digested locusts release the infective metacercariae that migrate to the pancreatic duct. Humans can be infected by accidental ingestion of locusts.
Symptoms and diagnosis of Eurytrema pancreaticum
Most infections are benign and cause only mild symptoms if at all. Nevertheless the pancreatic duct may be inflamed and enlarged. In heavy infections the duct can be occluded and the pancreatic tissues can be damaged as well. This can lead to more or less severe gastrointestinal disturbances (e.g. vomiting, flatulence, diarrhea, constipation, etc.) depending on the number of flukes. Such disturbances can result in production losses (reduced weight gains and feed conversion, decreased milk production, etc.).
Diagnosis is done by egg detection in the feces or by identification of the flukes after necropsy.
Prevention and control of Eurytrema pancreaticum
The most important preventative measure is to keep the snail population as low as possible. The snails that act as intermediate hosts are terrestrial but need humidity for development and survival. Effective drainage or anything else that keeps the pastures dry will reduce the snail population.
There are very few anthelmintics with a label claim against Eurytrema pancreaticum. There are reports on effective control with albendazole (7.5 mg/kg for sheep, 10 mg/kg for cattle) and praziquantel (20 mg/kg 2 days).
Chemical control of the snails with molluscicides (i.e. snail killers) such as copper sulphate, sodium pentachlorophenate, niclosamide, etc. can make sense for very specific purposes, e.g. for treating places where livestock congregates (water holes, feeding areas, salt licks, shade trees, etc) to keep them free of snails. However, trying to eradicate snails from a property is hopeless and useless. It is virtually impossible to treat every place where they can survive and they reproduce extremely quickly. Cleaned pastures would become re-infested very fast. In addition, it would be too expensive compared with the rather benign effects of pancreas flukes on livestock and very harmful for the environment. In fact, such molluscicides (mainly niclosamide) are approved only in a few countries as an aid in the prevention of human schistosomiasis (also called bilharziosis or snail fever).
For similar reasons, trying to eliminate the locusts that act as intermediate hosts of Eurytrema pancreaticum is not advisable either. Using insecticides for this purpose is not indicated, both for economic and ecologic reasons. Whatever insecticide spread on the pastures would kill numerous beneficial arthropods as well.
There are so far no vaccines against pancreas flukes. To learn more about vaccines against parasites of livestock and pets click here.
Biological control of pancreas flukes (i.e. using their natural enemies) is so far not feasible.
You may be interested in an article in this site on medicinal plants against external and internal parasites.
Ask your veterinary doctor! If available, follow more specific national or regional recommendations or regulations for pancreas fluke control.
Resistance of Eurytrema pancreaticum
So far there are no reports on resistance of Eurytrema species to flukicides.
This means that if a flukicide fails to achieve the expected efficacy, chance is very high that either the product was unsuited for the control of pancreas flukes, or it was used incorrectly.