The pathology of intracranial angiostrongylosis in rats.

Abstract Rats infected with third-stage larvae of Angiostrongylus cantonensis were killed at various periods after infection and the concentration of larvae in different parts of the central nervous system was determined. Some of the rats were examined histologically. Shortly after infection, larvae migrated in high concentrations from the spinal cord to the telencephalon, and lesions and eosinophilic infiltrations were found in the muscles and in and around many nerves. This process suggests that some of the larvae migrated along the nerves into the spinal cord and subsequently into the brain. In the brain, granulomas appeared around cast skins and dead parasites 5 days after infection. The entrance of the parasites into the subarachnoid space at 10 to 12 days after infection was accompanied by plasmocytic infiltration in the dural walls of cerebral sinuses and in arachnoid villi near the ostia of cerebral veins. These veins and the subarachnoid space became dilated. Large duroarachnoid herniae protruded into the extracranial veins. Inflammatory infiltrations formed epidurally around the spinal nerve roots and optic nerves. The worms left the cranial cavity by entering ruptured cerebral veins. The existence of arachnoid villi in rats has been demonstrated. The pathogenesis of intracranial angiostrongylosis in rats is discussed.