A chimeric Shiga toxoid according to the invention contains an enzymatically-inactivated StxA subunit and a native StxB subunit. This hybrid Shiga toxoid induces the production of broadly cross-reactive species of antibodies against Shiga toxin following immunization. The StxA subunit is modified so that it is enzymatically inactive. The invention thus encompasses the Shiga toxoid or fragments thereof and the nucleic acid sequence of the Shiga toxoid or fragments thereof. The invention further encompasses the production of a Shiga toxoid, the production of antibodies using the Shiga toxoid and methods of productions, and an immunogenic composition containing the Shiga toxoid.