GALT, IOWA — Wright County Egg is in the process of recalling approximately 228 million eggs. The company has recalled eggs produced by their farms because they have the potential to be contaminated with Salmonella.

The recalled eggs are sold under the Lucerne, Albertson, Mountain Dairy, Ralph’s, Boomsma’s, Sunshine, Hillandale, Trafficanda, Farm Fresh, Shoreland, Lund, Dutch Farms and Kemps brand names.

Since May 2010, the Centers for Disease Control and Prevention, Atlanta, has identified a nationwide, four-fold increase in the number of Salmonella Enteritidis (S.E.) isolates through PulseNet, the national subtyping network made up of state and local public health laboratories and federal food regulatory laboratories. The C.D.C. received reports of approximately 200 S.E. cases every week during late June and early July. Normally, the C.D.C. has received an average of some 50 reports of S.E. illness each week for the past five years. Many states have also reported increases of this pattern since May 2010, according to the agency.

Epidemiologic investigations conducted by public health officials in California, Colorado, and Minnesota have revealed several restaurants or events where more than one person ill with this type of S.E. has eaten.

Preliminary information from the investigations suggests shell eggs are the likely source of infections.

The F.D.A. and C.D.C. conducted a traceback investigation and found many of the restaurants received shell eggs from Wright County Egg. The F.D.A. is currently conducting an investigation at the firm in Iowa. The investigation involves sampling, records review and looking for potential sources of contamination, such as feed.