Emergence of Shiga toxin 1 genes within Shigella dysenteriae type 4 isolates from travelers returning from the Island of Hispañola.

Shiga toxins are produced by Shigella dysenteriae type 1 and certain strains of Escherichia coli. Three cases of Shiga toxin-producing S. dysenteriae type 4 were identified among travelers to the island of Hispañola between 2002 and 2005. Clinical and public health practitioners should be aware of this newly identified strain.