SAN ANSELMO, CA - OCTOBER 09: Packages of Foster Farms chicken are for sale in a cooler at a grocery store on October 9, 2013 in San Anselmo, California. The U.S. Department of Agriculture is threatening to shutter three Foster Farms chicken processing plants in California after nearly 300 people in 17 states have become sick due to an outbreak of salmonella. (Photo by Justin Sullivan/Getty Images)
A truck enters the Foster Farms processing plant on Thursday, Oct. 10, 2013, in Livingston, Calif. The plant is one of three California poultry processing plants linked to a salmonella outbreak that has sickened 278 people across the country. The Agriculture Department said that Foster Farms has until Thursday to tell the USDA how it will fix the problem. Sampling by USDA in September showed that raw chicken processed by those facilities included strains of salmonella that were linked to the outbreak. (AP Photo/Rich Pedroncelli)
A feed truck is sprayed by Foster Farms employee George Lezama before entering a sterile area at one of the company's farms April 13, 2006 in Merced, Calif. "Biosecurity" is the buzzword du jour at chicken, turkey and egg operations across the country. A bird flu pandemic sweeping through flocks in Southeast Asia and beyond has spurred American commercial farmers to tighten defenses against threats. (AP Photo/Ben Margot)
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LIVINGSTON, Calif. (AP) - Federal health officials say a salmonella outbreak linked to Foster Farms chicken isn't over and has now infected 524 people in 25 states and Puerto Rico.
The Centers for Disease Control and Prevention released the updated numbers on Wednesday. The agency reported in January that the outbreak appeared to be over. It has been going on since March 2013.
The CDC noted an uptick in illnesses in February.
The outbreak led to a public health alert from the U.S. Department of Agriculture for raw chicken packaged at three Foster Farms facilities in California.
Though no one has died, the CDC says the outbreak strains have been resistant to several commonly prescribed antibiotics.
Foster Farms says it has implemented a salmonella control program that has reduced the prevalence of salmonella in its products.