Allergy to IXIARO and BIKEN Japanese encephalitis vaccines.

We describe an allergic reaction to both mouse brain-derived BIKEN and Vero cell-derived IXIARO Japanese encephalitis (JE) vaccines in a single traveler. In the absence of the stabilizers and murine proteins in the BIKEN vaccine, a common factor in both vaccines is likely to be responsible, possibly JE virus antigen itself.