Alaria canis

Allaria canis is a digenean trematode of wild canids, which reaches a length of 2.5 - 6 mm × 0.5 -2 mm. It lives in the small intestine and reaches prevalence rates of up to 30%. See Fig. 1

Fig. 1

Life cycle of Alaria canis (A. americana). 1 The adults (2.5–4.2 mm long) live in the anterior third of the small intestine of the final hosts (canids). 2 The operculate eggs are unembryonated when laid. 3 Larvae (miracidia) hatch in about 2 weeks after reaching water. 4 Miracidia swim actively and enter several species of helisomid snail (first intermediate host), inside which mother sporocyst and daughter sporocyst are produced. The latter give rise to cercariae. 5 The furcocercous cercariae leave the snail during daylight hours and swim to the water surface, where they hang upside down. 6 If tadpoles (as intermediate hosts of the second type) pass by, the cercariae penetrate the skin. In about 2 weeks the cercariae become transformed into mesocercariae (6.1, 6.2 show surface view). 7–9...