Acute visceral cysticercosis by Taenia hydatigena in lambs: ultrasonographic findings

Cysticercosis by Cysticercus tenuicollis is a metacestode infection caused by the larval stage of Taenia hydatigena, an intestinal tapeworm of dogs and wild canids. The mature cysticerci are usually found on the omentum, mesentery, peritoneum and less frequently on the pleura and pericardium. The migrating larvae can be found mostly in the liver parenchyma causing a traumatic hepatitis in young animals. Most infections are chronic and asymptomatic, and they are diagnosed at abattoir. The acute form of infection is unusual in sheep and reports of death in lambs are scanty. In March 2018 fifteen female replacements lambs from a flock of 100 individuals, 4 months old, weighing from 15 to 20 kg, presented anorexia, lethargy, weakness, neurological signs and death. Twelve of them underwent hepatic ultrasonography. The ultrasound examination was performed with a portable ultrasound unit equipped with two multifrequency linear and microconvex transducers. Examinations were performed on standing or left lateral recumbent animals. The liver was visualized by placing the probe caudally to the last right rib or between the right intercostal spaces. Bi-dimensional ultrasonography evidenced the following alterations: hepatomegaly, rounded and irregular liver margins, irregularity of both visceral and diaphragmatic surfaces. Along the visceral surface several animals presented cystic structures (∼0,7 cm) characterized by thick and hyperechoic walls containing a hyperechoic mural branching component surrounded by anechoic fluid. Hepatic parenchyma appeared diffusely heterogeneous and crossed by numerous, irregular, anechoic tracts ranging from 1 to 2 cm in length and 0,1 to 0,2 cm in width. In some animals intraparenchymal cysts of ∼0,3 cm were visualized. These cysts contained a point-like hyperechoic structure surrounded by anechoic fluid. A suspected diagnosis of acute traumatic hepatitis secondary to parasitic migration was made. The diagnosis was subsequently confirmed by the autoptic examination and molecular characterization of isolates. Our results evidenced that hepatic ultrasonography is a valuable method to perform an intra-vitam diagnosis of acute cysticercosis in lambs.