Histopathology of CNS and nasal infections caused by Trichobilharzia regenti in vertebrates

In bird infections caused by Trichobilharzia regenti, the central nervous s ystem (CNS) represents probably the main route to the nasal cavity, where m aturation of the parasite occurs. However, in an abnormal mouse host, devel opment is incomplete and is accompanied by a strong affinity of the parasit e to the CNS. In order to explain pathological changes caused by the parasi te, a histological study of cross-sections from the CNS and nasal cavity wa s performed. In the CNS of duck and mouse, immature flukes were found. Cros s-sections showed parasites located either in meninges or in matter of vari ous parts of the spinal cord and brain. In the spinal cord, the submeningea l location led to a strong inflammatory reaction around the schistosomula a nd resulted in eosinophilic meningitis. In the white and gray matter of the spinal cord and in the white matter of the brain, a cellular infiltration of spongy tissue surrounded the immature parasites; and we observed dystrop hic and necrotic changes of neurons, perivascular eosinophilic inflammation in the spinal cord and brain, and cell infiltration around the central can al of the spinal cord. T. regenti adults and eggs were detected in the nasa l mucosa of infected ducklings; and aging of the eggs resulted in various h ost reactions, ranging from focal accumulation of cells to the formation of granulomas. Histopathological changes may explain symptoms described previ ously for prepatent and patent phases of infections caused by T. regenti, i .e., neuromotor abnormalities in birds and mammals and hemorrhages/petechia e in birds, respectively.