Five of the illnesses (2 mother-newborn pairs and a newborn) were related to pregnancy and all patients are Hispanic.
Further investigation is needed to determine the source of the patients’ illnesses, including whether they relate to food products that tested positive for Listeria, said the US Centers for Disease Control and Prevention (CDC).
Detection in Virginia
The Virginia Department of Agriculture and Consumer Services (VDACS) and the Virginia Division of Consolidated Laboratories (DCLS) detected Listeria monocytogenes in cheese produced by Roos Foods Inc. of Kenton, Delaware.
It was isolated from a sample of Cuajada en Terron (Fresh Cheese Curd) manufactured by Roos Foods and collected by VDACS food safety inspectors at Mega Mart, a retail store in Manassas, Virginia.
Seven people have been sickened in Maryland and one death was reported in California.
Pulsed-field gel electrophoresis (PFGE) is being used alongside whole genome sequencing. The 5 isolates already sequenced are closely related, said the CDC.
Available information shows illness dates range from 1 August to 27 November 2013.
All patients in Maryland reported consuming soft or semi-soft Hispanic-style cheese and shopped at different locations of the same food store chain, said the CDC.
Brands produced by Roos Foods include: Santa Rosa de Lima, Amigo, Mexicana, Suyapa, La Chapina and La Purisima Crema Nica.
Presumed positive
As part of an ongoing investigation, testing of cheese products by the Maryland Department of Health and Mental Hygiene (DHMH) is presumptively positive for Listeria bacteria.
While confirmatory testing is underway, DHMH advises consumers not to eat any cheese products made by Roos Foods, or foods that have been made with these cheeses.
The DC Department of Health (DOH) advised district residents not to purchase or consume Roos cheese products.
No lot or date coding information has been identified; but as a measure of precaution district food safety officials pulled the products from shelves.
Any individuals who purchased the product should not consume and should discard any remaining portions, said the agency.