The patient count in an outbreak of infections from Listeria monocytogenes is increasing as the Food and Drug Administration continues to look for a cause.

As of March 27, the outbreak had sickened 30 people, up from 28 a week ago. The FDA has not reported the age range of the patients or wher they live. There are likely at least 60 patients in the outbreak because of the number of patients who go undetected. 

The Centers for Disease Control and Prevention says that for every patient who is confirmed in a Listeria outbreak there is another who goes undetected because some do not seek medical attention and others are not specifically tested for Listeria.

The FDA has begun a site inspection and sample testing but has not reported what location is being inspected or what it is sampling. The agency first reported the outbreak on March 13.

In other outbreak news, the FDA has adjusted the number of patients in an outbreak of infections caused by Salmonella Newport. The agency is now reporting that 35 people have been sickened in the outbreak. The FDA first reported the outbreak on Feb. 20.

The agency has declared the outbreak over without having identified a source of the pathogen. There are likely many more outbreak patients who have gone undetected. The CDC reports that for every patient confirmed in a Salmonella outbreak there are 29 who are not detected because some do not seek medical attention and others are not specifically tested for Salmonella.

For a Listeria outbreak first reported on Jan. 15, the FDA has closed its investigation. There were 36 confirmed patients in the outbreak. The FDA initiated traceback, site inspection and sample testing but it did not report what food it traced or sampled. The agency also did not report what location it inspected.

For another outbreak of Listeria infections the patient count remains steady at three. The source of the pathogen has not yet been found. The FDA first reported the outbreak on March 5. The agency has initiated traceback, site inspection and sample testing but has not reported what food is being traced or what location is being inspected. The agency has also not reported what food it is testing.