Fascioloides magna

Fascioloides magna, also known as giant liver fluke, large American liver fluke or deer fluke, is trematode parasite that occurs in wild and domestic ruminants in North America and Europe. Adult flukes occur in the liver of the definitive host and feed on blood. Mature flukes measure in length × in width, and have an oval dorso-ventrally flattened body with oral and ventral sucker. The flukes are reddish-brown in colour and are covered by tegument. As with other digenean trematodes, the life cycle includes intramolluscan phase in snails. The parasite is currently distributed in wild ruminants in North America and Europe, including Austria, Canada, the Czech Republic, Croatia, Germany, Hungary, Italy, Poland, Serbia, Slovakia, and the United States. Fascioloides magna is essentially of North American origin but the parasite was introduced into Europe with imported game animals at the second half of the 19th century. In spite of being native to North America the fluke was first described in Italy. In 1875, Bassi observed massive deaths of red deer in the Royal Park (now La Mandria Regional Park) near Torino, Italy. The signs were similar to well known fasciolosis in sheep. He named it Distomum magnum. The author believed that the parasite was introduced into the park in wapiti imported from the United States in 1865. Most workers did not accept Bassi’s species because of his poor description. From 1882 to 1892, the fluke was recorded from different areas of the United States and described separately by many authors. Later, Stiles (1894) pointed out that the American findings are identical with species described previously by Bassi. Stiles made a complete morphological description of the adult fluke and named it Fasciola magna (Bassi 1875) Stiles 1894. In 1917, Ward showed that owing to the lack of the distinct anterior cone and the fact that vitellaria are confined to the region ventral to the intestinal branches, he established a new genus Fascioloides and rename it to Fascioloides magna (Bassi 1875) Ward 1917.