Mixtures of viruses that attack inflammatory bowel disease–causing bacteria in mice also survive the digestive tract and are well-tolerated in humans, a study finds.

Studies point to the life-saving record of fecal transplants for patients infected with C. diff, despite a recent death. Doctors are now testing the procedure for other conditions.

The second phase of the Human Microbiome Project reports on microbial composition in prediabetes, inflammatory bowel disease, and pregnancy.