Myocardial and pancreatic necrosis induced by rocio virus, a new flavivirus

Rocio virus, the etiologic agent of an epidemic of human encephalitis in Sao Paulo State, Brazil, produced a severe, generalized infection in suckling hamsters. Of the non-neural organs, heart and pancreas were most severely affected. Focal necrosis was apparent in the heart 48 hr after intracerebral inoculation, and by 72 hr it was widespread. Virus particles were seen within cisternae in both the myocardial fibers and the smooth musculature of small blood vessels. The pancreas exhibited minimal changes at 48 hr but within 72 hr there was extensive necrosis, with both exocrine and endocrine portions of the organ severely affected. Virus particles were found mostly within the acinar cells where frequently they were sequestered in the zymogen granules, and within the beta cells in the islets. They were also seen in vacuoles in unmyelinated nerve fibers supplying the pancreas.