Parents are being warned about a potentially life-threatening condition in which an infant's intestines wind up twisted.

The Food and Drug Administration says it's seeing cases involving children who've been vaccinated against rotavirus. But it's unclear if the new vaccine is to blame for nearly 30 new cases. Experts say the condition can occur spontaneously.

Still, there's extra concern because eight years ago, an earlier rotavirus vaccine was pulled because it was linked to the intestine condition.

The FDA says it wants to hear about any other cases, so it can better assess the risks from the shots. But the vaccine's co-inventor insists it's a small number of cases, and he says that suggests there's nothing wrong with the shots.

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