There have been reported cases of Enterobacter sakazakii infections due to contaminated infant formula in only a few developed countries. It is likely that there is a significant underreporting of infections in all countries. The absence of reports is probably due to a lack of awareness of the problem rather than an absence of illness. In general, the limitations of current surveillance systems in most countries would add to the explanation for the lack of reported cases. Since infant formula is widely used, the presence of Enterobacter sakazakii in infant formula and its potential effects in infants could well be a significant public health problem in most countries.