In Reply.—Dr O'Donovan raises an interesting question concerning the possible interaction of viruses and bacteria in diarrheal disease. Presumably, he is alluding to bacteriophages, since he uses the analogy to phage-induced toxin production by Corynebacterium diphtheriae. This is an unlikely postulate. Gyles et al1 have demonstrated that heat-stable and heat-labile toxin production by Escherichia coli is plasmid mediated, the so-called Ent plasmid.
The "largely unrewarding search for pathogenic enteroviruses" of years past has reaped a bountiful harvest in the past two years with numerous reports from all over the world of orbiviruses (also called rotaviruses or duoviruses) in substantial numbers of children with acute diarrheal disease. In the largest study to date, Davidson et al2 identified duoviruses in 52% of 378 children with diarrhea and in none of 116 control children. The Norwalk agent and other viruses are less common causes.