According to a report today by the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP) and a risk assessment statement issued by the European Centre for Disease Control and Prevention (ECDC), health officials in Germany are now investigating a cluster of E. coli O104:H4 infections at a German school located in western Germany’s North Rhine-Westphalia state, Kreis Praderborn.

Health authorities reported that 4 individuals have become infected since late June. Three of those individuals later developed hemolytic uremic syndrome (HUS). However, importantly, ECDC noted that after a preliminary screening at the school, 22 of 30 children, 3 kitchen workers, 4 workers in the childcare center, and 3 staff members of a catering company at the school had asymptomatic E. coli O104:H4 infections.

According to CIDRAP’s report, this development is cause for concern:

The ECDC said the possibility that the strain has a longer incubation may mean that a low infectious dose is involved, which might increase the likelihood of person-to-person spread or foodborne transmission from infected people. Though person-to-person spread of the disease has occurred in the outbreak, it doesn’t seem to be playing an important role. So far person-to-person spread has not sparked outbreaks at daycare centers, schools, or nursing homes.

New findings about the asymptomatic infections, along with a lower but continuing level of new cases and clusters, suggest that Europe’s E coli outbreak is in a transition phase, from a sprout-focused event to one that is driven by contaminated seeds that may still be on the market or in households, along with new foodborne transmission vehicles and person-to-person transmission, the ECDC said.

ECDC is continuously monitoring the E. coli outbreak and publishes a daily epidemiological update which includes the most recent numbers of HUS and non-HUS cases reported by EU Member States. So far the ECDC has received 3,848 reports of E. coli O104:H4 infections, including 763 with HUS and 44 deaths, not including the United States.