Parasitic females of Strongyloides papillosus as a pathogenetic stage for sudden cardiac death in infected lambs.

The present study was aimed at elucidating the responsibility of parasitic females for sudden cardiac death following Strongyloides papillosus infection in calves. A preliminary experiment demonstrated a percutaneous infection with S. papillosus infective larvae to cause sudden cardiac death in lambs as in calves, indicating lambs could serve as a model to study fatal stronglyloidiasis in calves. Parasitic females of S. papillosus were inoculated into the duodenum of lambs. Lambs given live worms developed continuous sinus tachycardia immediately after inoculation, and died of sudden cardiac arrest by ventricular fibrillation through a phase of the disease identical to the case of percutaneous larval infection. The lambs had high fecal egg counts at the time of death. Inoculation of homogenized worms did not produce fatal arrhythmias. These results demonstrate that live parasitic females of S. papillosus in the small intestine are responsible for cardiac dysfunction regardless of the presence or absence of migratory larvae.