Federal officials are investigating a new outbreak of Listeria infections and have initiated testing in two other investigations.

The new Listeria monocytogenes outbreak has sickened at least 15 people, but the Food and Drug Administration has not yet identified a food source for the pathogen. In keeping with its usual process, the FDA has not released any information about the patients, such as age, and has not reported wher they live.

As of April 12 the FDA had not begun traceback efforts or initiated any on-site inspections or sample testing in relation to the new outbreak of Listeria monocytogenes infections.

In another outbreak, also caused by Listeria, the FDA is reporting that a food source has not been identified, but it has begun on-site inspection of an unnamed company. The agency has begun sample collection and testing, but it has not reported what is being tested. The patient count in the outbreak remains at 17.

In a third investigation into reports of “adverse events,” the FDA reports that the patient count has increased to 38, up from the 31 reported a week ago. Although the agency is not revealing what the “adverse events” are or what food is involved, it has begun traceback efforts. The agency has also begun sample collection and analysis, but is not reporting what is being tested.

The agency also has ongoing investigations into an outbreak of norovirus infections traced to raw oysters from British Columbia, Canada, and an outbreak of Salmonella Saintpaul infections from an unknown source.  The norovirus outbreak traced to the oysters has sickened more than 100 people in the United States and more than 300 in Canada.

The FDA is also continuing to investigate an outbreak of cronobacter infections linked to infant formula made by Abbott Nutrition that has sickened four babies with two deaths under investigation.

The table below shows information about outbreak investigations being managed by FDA’s CORE Response Teams. The investigations are in a variety of stages. Some outbreaks have limited information with active investigations ongoing, others may be near completion. The table below has been abbreviated to show only active investigations.

The Food and Drug Administration will issue public health advisories for outbreak investigations that result in “specific, actionable steps for consumers — such as throwing out or avoiding specific foods — to take to protect themselves,” according to the outbreak table page.

Not all recalls and alerts result in an outbreak of foodborne illness. Not all outbreaks result in recalls.

Outbreak investigations that do not result in specific, actionable steps for consumers may or may not conclusively identify a source or reveal any contributing factors, according to CORE’s outbreak table page. If a source(s) and/or contributing factors are identified that could inform future prevention, FDA commits to providing a summary of those findings, according to CORE officials.

Click here to visit the FDA page that has a complete list of outbreak investigations and links to outbreak information.