The recall of more than half-a-billion eggs in a salmonella scare, one of the largest egg recalls in American history, is spreading, sickening nearly 1,300 people and severely hurting the country’s $6 billion egg industry.

As authorities investigates the egg recall and the related salmonella outbreak, 18 states including Arkansas, California, Iowa, Illinois, Indiana, Kansas, Minnesota, Missouri, Nebraska, Ohio, Texas, Wisconsin and Michigan are now affected.

Michigan is the latest to join the ranks with its Department of Agriculture saying that eggs associated with the national recall have been distributed in the state.

The current outbreak began in May and was traced to two Iowa farms, the Food and Drug Administration (FDA) said.

One of them, Wright County Egg, has recalled 380 million eggs; the other, Hillandale Farms, recalled 170 million eggs.

The recall of 550 million eggs is another blow to the nation’s $6-billion egg industry, the Los Angeles Times reported.

“I don’t know what’s caused this current situation, or what the tie is between the outbreaks in these two farms, but we need to find out,” said Howard Magwire, a vice president of the national trade group United Egg Producers.

FDA Commissioner Margaret Hamburg said new federal regulations that took effect in July could have prevented the recall.

The new regulations went into effect July 9, requiring egg producers with more than 3,000 hens to take measures designed to prevent the spread of Salmonellosis, an infection caused by Salmonella bacteria. Most people who get infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps, 8 to 72 hours after infection.

As many as 1,300 cases of salmonella poisoning have been reported after the two Iowa farms recalled more than a half-billion eggs, U.S. media reports said.

“We believe that had these rules been in place at an earlier time, it would have very likely enabled us to identify the problems on this farm before this kind of outbreak occurred,” Hamburg was quoted as saying by CNN.

Supporters of a long-stalled bill to bolster the safety of America’s food supply are hoping the egg-linked salmonella outbreak will give them momentum to pass their bill in the Senate as early as next month.

The bipartisan bill would give new powers and resources to the FDA to crack down on risky food suppliers in the U.S. and abroad. It would boost the agency’s ability to track suspected foods and remove them from stores faster.