Amphistomiasis

Amphistomiasis is a parasitic disease of livestock animals, more commonly of cattle and sheep, and humans caused by immature helminthic flatworms belonging to the order Echinostomida. The term amphistomiasis is used for broader connotation implying the disease inflicted by members of Echinostomida including the family Paramphistomidae/Gastrodiscidae (to be precise, the species Gastrodiscoides hominis); whereas paramphistomiasis is restricted to that of the members of the family Paramphistomidae only. G. discoides and Watsonius watsoni are responsible for the disease in humans, while most paramphistomes are responsible in livestock animals, and some wild mammals. In livestock industry the disease causes heavy economic backlashes due to poor production of milk, meat and wool.

Signs and symptoms

Symptoms include:

Physical weakness, emaciation or lethargy

Foul smell of faeces, greasy consistency and scour or diarrhoea

Anorexia, refusal to eat food

Dehydration and frequent drinking of water

Submaxillary oedema (bottle jaw) and pale mucous membrane

Intestinal bleeding (haemorrhagic enteritis) with anaemia and low blood protein (hypoproteinaemia)

Damage to the bile duct, and liver cirrhosis

In humans (specifically gastrodiscoidiasis) symptoms include diarrhoea, fever, abdominal pain, colic, and an increased mucus production. Large amounts of eggs can cause tissue reactions in the heart or mesenteric lymphatics, which may lead to death. Mortality among native Assamese children is attributed to this infection.

Cause

Amphistomiasis in farm and wild mammals is due to infection of paramphistomes, such as the species of Paramphistomum, Calicophoron, Cotylophoron, Pseudophisthodiscus, etc. These are essentially rumen flukes, of which Paramphistomum cervi is the most notorious in terms of prevalence and pathogenicity. Infection occurs through ingestion of contaminated vegetables and raw meat, in which the viable infective metacercaria are deposited from snails, which are the intermediate hosts.