MONDAY, Aug. 23 (HealthDay News) -- There may be more recalls of eggs potentially tainted by salmonella, the head of the U.S. Food and Drug Administration said Monday.

"We may see some additional sort of sub-recalls over the next couple of days, maybe even weeks, as we better understand the network of distribution of these eggs that are contaminated," agency director Dr. Margaret Hamburg told NBC's Today show.

At least 550 million eggs have been recalled so far, according to federal officials.

Hamburg also believes that new laws are needed to expand the FDA's enforcement from a mostly reactive stance on food safety to a more "preventive approach."

Appearing on the network morning news programs, Hamburg said the FDA is taking the salmonella outbreak "very, very seriously." But, she added, Congress should pass pending legislation that would give her agency greater enforcement power, including new authority over imported food, the Associated Press reported.

"We need better abilities and authorities to put in place these preventive controls and hold companies accountable," Hamburg said.

She also offered some practical advice for consumers, urging them to avoid runny, over-easy "egg yolks for mopping up with toast."

During a press conference Monday afternoon, federal officials said they have received nearly 2,000 reports of salmonella infections in people in about 22 states, a number they predicted would continue to grow in the coming weeks. Between Aug. 19 and 23, the U.S. Centers for Disease Control and Prevention received an additional 40 reports of infections, though those have not yet been confirmed as linked to the egg recall.

The actual number of people infected may be considerably higher, since not everyone who gets ill with salmonella seeks medical attention, officials said. Some estimates put the actual number of those sickened at 30 to 38 times the number reported, said Dr. Christopher R. Braden, acting director of the CDC's Division of Foodborne, Waterborne and Environmental Diseases.

Potential sources of salmonella contamination can include rodents, shipments of contaminated chicks or tainted feed, Hamburg said.

On Saturday, it was reported that the two Iowa farms linked to the disease outbreak -- Wright County Egg and Hillandale Farms -- share suppliers of chickens and chicken feed. Jewanna Porter, a spokeswoman for the egg industry, said the company Quality Egg supplies young chickens and feed to both Wright County Egg and Hillandale Farms. The two share other suppliers, she said, but she did not name them, the AP reported.

The egg industry has consolidated in recent years, meaning there are fewer, bigger businesses controlling much of the nation's egg supply. Further complicating matters, the salmonella outbreak has focused attention on a potential difficulty with federal inspection of egg farms. The FDA oversees inspections of shell eggs, while the Agriculture Department is charged with inspecting other egg products, the news service said.

On Friday, Hillandale Farms of New Hampton, Iowa, said it was voluntarily recalling 170 million shell eggs produced since April that were sent to 14 states in the Midwest and West because there have been laboratory-confirmed cases of Salmonella enteritidis associated with some of the eggs.

Hillandale said the eggs covered by its recall were distributed to grocery distribution centers, retail grocery stores and food-service companies that service or are located in Arkansas, California, Iowa, Illinois, Indiana, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, Texas, and Wisconsin.

The eggs were distributed under the following brand names: Hillandale Farms, Sunny Farms, and Sunny Meadow in 6-egg cartons, dozen-egg cartons, 18-egg cartons, 30-egg packages, and 5-dozen cases. Loose eggs were packaged under the following brand names: Wholesome Farms and West Creek in 15 and 30-dozen tray packs, Hillandale said in a news release.

Last Wednesday, Wright County Egg, the other Iowa company at the center of the massive recall, dramatically broadened its nationwide recall to 380 million eggs.

"We don't have an evidence other farms are involved in this outbreak, but the FDA is continuing to investigate," Hamburg said Monday.

Wright County Egg products were distributed to wholesalers and food-service companies nationwide under multiple brand names: Lucerne, Albertson, Mountain Dairy, Ralph's, Boomsma's, Sunshine, Hillandale, Trafficanda, Farm Fresh, Shoreland, Lund, Dutch Farms and Kemps.

Additional recalls would probably involve eggs from the batches that were already identified as possibly tainted, but were sold to wholesalers and repackaged or rebranded by other sellers, according to FDA officials.

The outbreak, which apparently began in May, started several weeks before the July introduction of new federal safety rules intended to reduce the risk of salmonella in eggs, federal officials said.

At Monday's press conference, officials said consumers should not worry about eggs from the two Iowa farms that are contained in processed foods such as cake mix or cookies. Those eggs would have been pasteurized before being incorporated into those products, which would have killed salmonella.

In healthy people, salmonella, a food-borne bacteria, can cause fever, abdominal cramps and diarrhea and usually lasts four to seven days. However, contamination can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems.

The FDA advises consumers to:

  • Toss recalled eggs or return them to the store for a refund.
  • See a doctor if you think you are ill after eating recalled eggs.
  • Keep eggs refrigerated at all times.
  • Throw out cracked or dirty eggs.
  • Wash hands, utensils and preparation surfaces with soap and water after contact with raw eggs.
  • Cook eggs until both the white and the yolk are firm and eat promptly after cooking.
  • The FDA also warned consumers not to keep eggs warm or at room temperature for more than two hours, and not to eat raw eggs or restaurant dishes made with raw, undercooked or unpasteurized eggs.

    Eating undercooked eggs should also be avoided, especially by young children, the elderly and people with weakened immune systems or debilitating illness, the agency added.

    Harmful bacteria such as salmonella are the most common cause of foodborne illnesses, according to federal health officials.

    More information

    For the latest information on the salmonella outbreak, visit the U.S. Food and Drug Administration.