(CNN) -- Federal public health officials are investigating a salmonella outbreak that has infected 22 people in 10 states, the Centers for Disease Control and Prevention announced Friday.

The infections are linked to the consumption of raw alfalfa sprouts, the CDC said.

California-based Caldwell Fresh Foods is recalling all alfalfa sprouts manufactured under three of its brands because they may be contaminated with salmonella, the company said Friday. Caldwell said its alfalfa sprouts have been associated with the outbreak.

There have been no deaths reported from the outbreak, but four of those infected have been hospitalized, Caldwell Fresh Foods said in a statement Friday.

CDC is collaborating the U.S. Food and Drug Administration and with state public health officials to investigate the salmonella outbreak, the CDC said in a statement Friday.

One of those infected was an infant hospitalized in Oregon, an Oregon Department of Health official told CNN. The baby had been eating alfalfa sprouts, said Paul Cieslak, manager of the state health department's communicable disease section.

CDC is collaborating with the U.S. Food and Drug Administration and state public health officials to investigate the strain, called Salmonella Newport, the CDC said in a statement Friday.

The initial investigation traced the implicated raw alfalfa sprouts to a single sprout processor in California, the CDC said, though it did not name Caldwell Fresh Foods directly. The CDC did not respond to requests for comment on Friday.

Eleven of those sickened are in California, Caldwell Fresh Foods said, with the most recent known illness beginning on May 2.

The company, which said it voluntarily issued the recall, distributed the alfalfa sprouts under its Caldwell Fresh Foods, Nature's Choice and California Exotics brands.

The alfalfa sprouts were distributed to various restaurants, delicatessens and retailers across the country, Caldwell Fresh Foods said. In California, Caldwell products are sold at Trader Joe's and Wal-Mart stores, among others.

Salmonella infections linked to the outbreak have also been identified in Arizona, Colorado, Idaho, Illinois, Missouri, New Mexico, Nevada, Oregon and Wisconsin, the CDC said.

The first illness linked to the outbreak began on March 1, the agency said.

Most people infected with salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection, the CDC said. The illness usually lasts four to seven days.

Although most people recover without treatment, infants, the elderly and those with weakened immune systems can develop severe illness that can cause death unless the person is treated promptly with antibiotics, the CDC said.

Illnesses that occurred since May 2 might not yet be reported because it takes an average of two to three weeks from when a person becomes ill until the salmonella infection is reported, the CDC said.

CNN's Greg Morrison contributed to this report.