(USA TODAY) -- A national outbreak of salmonella in eggs has sickened hundreds of people since May and appears to be ongoing, experts at the Centers for Disease Control and Prevention say. The outbreak has been tracked to in-shell eggs from Wright County Egg in Galt, Iowa, which has launched a recall.
The Associated Press estimates the total number of eggs recalled at 228 million.
Eggs from the company were sold under multiple brand names: Lucerne, Albertson, Mountain Dairy, Ralph's, Boomsma's, Sunshine, Hillandale, Trafficanda, Farm Fresh, Shoreland, Lund, Dutch Farms and Kemps. They were distributed nationwide. The recall was launched Aug. 13.
The recall covers eggs in their shells packed between May 16 and Aug. 13. They come in cartons ranging from six to 18 eggs and are marked with plant numbers P-1026, P-1413 and P-1946. The eggs should be returned for a refund and not consumed.
The type of salmonella causing the outbreak, salmonella enteritidis, is the most common form. The normal level of laboratory-confirmed cases nationally for this specific type is about 50 cases per week. When that jumped to 200 cases a week in June, public health workers realized they had a problem, says Casey Barton Behravesh, a veterinary epidemiologist with the CDC. Many states had reported increases since May.
Completely cooking eggs reduces the amount of salmonella bacteria in the eggs. Each case of laboratory-confirmed salmonella usually represents 30 cases that were not reported, public health research shows. So the number of people sickened in this outbreak could be in the thousands.
"This certainly has the potential to be a very large outbreak both given the apparent number of reported cases so far and also the fact that many of these eggs may still be in consumer refrigerators," says Caroline Smith DeWaal, food safety director of the Center for Science in the Public Interest.
CDC is not reporting deaths or hospitalizations in the outbreak because it's difficult to determine if they are related to eggs from Wright County Egg or are part of the expected "background" level of cases from other sources, Behravesh says.
The Food and Drug Administration currently has teams on site at Wright County Egg, says Food and Drug Administration spokeswoman Patricia El-Hinnawy.
Salmonella can cause fever, abdominal cramps and diarrhea and usually lasts four to seven days.