Induction of congenital hydrocephalus in hamsters with attenuated and natural strains of mumps virus.

The abilities of a low-passage strain and of a live, attenuated vaccine strain of mumps virus to induce congenital hydrocephalus in hamsters were tested by intraamniotic inoculation on the 10th day of pregnancy. Examination of term fetuses and neonates, with cytoplasmic inclusions, cytopathic effects, and specific immunofluorescence used as indicators, demonstrated an oronasal portal of entry for both strains. The vaccine strain appeared to be more pathogenic; it spread primarily into the respiratory tract and hence to the central nervous system. Inclusions were observed as long as 21 days after inoculation. Hydrocephalus and ependymal involvement, potentially capable of producing aqueductal stenosis, were observed in 19 of 81 animals studied 11-29 days after inoculation.