Federal regulators have received reports of 25 people falling ill and recalled 13 million pounds of raw almonds supplied by Paramount Farms in California.

The size of the recall announced this past week is likely to grow as federal investigators continue to identify distributors and repackagers of almonds that originated from Paramount, which grows its almonds in the heart of California’s Central Valley.

The recall covers millions of packages sold under a variety of brand names across the country as well as almonds shipped to eight countries. The FDA has received reports of salmonella enteritidis, a type of food poisoning, in at least six states so far.

No fatalities have been reported.

The industry has spent about $4 million to improve manufacturing and agricultural practices and has been examining technologies, including pasteurizing the almonds with low heat or gas, to prevent salmonella contamination.

Heat, which can come from any kind of cooking, roasting or commercial processing of almonds, is usually sufficient to kill bacteria, experts said. Blue Diamond, a cooperative that represents about two-thirds of California’s almond growers, began pasteurizing their almonds three years ago after the last outbreak.

Paramount Farms has not pasteurized raw almonds in the past, but two weeks ago it began to use a gas method of pasteurization for all of its raw almonds.

California accounts for 100 percent of U.S. almond production and expects production to grow by at least 50 percent over the next five years. California also produces about 80 percent of the world’s almonds.

Scientifically, it is possible to treat the almonds, then return them to the marketplace. That was done after the 2001 outbreak, although in that case, most of the almonds had been shipped in bulk and had not yet made it to smaller packages.

It is not known yet if the recalled almonds will be treated and returned to store shelves.