Salmonella continued its spread across the United States, with more than 1,000 people infected so far, the Center for Disease Control and Prevention (CDC) announced on Wednesday. (File Photo) Photo Gallery>>>

    LOS ANGELES, July 9 (Xinhua) -- Salmonella continued its spread across the United States, with more than 1,000 people infected so far, the Center for Disease Control and Prevention (CDC) announced on Wednesday.

    The CDC urged people to remain on high alert against the worst food borne outbreak in at least a decade.

    It listed raw jalapeno and serrano peppers as suspected source that caused the disease initially linked to raw tomatoes.

    But certain raw tomatoes - red round, plum and Roma - remain a chief suspect, the CDC said, stressing again that all consumers should avoid them unless they were harvested in areas cleared of suspicion.

    The most vulnerable are the elderly, people with weak immune systems and infants, the agency said.

    Raw jalapenos caused some of the illnesses, CDC said, concluding investigations of two clusters of sick people who ate at the same restaurant or catered event.

    But jalapenos cannot be the sole culprit - because many of the patients insist they did not eat hot peppers or foods that contain them, CDC food safety chief Dr. Robert Tauxe said.

    In some clusters of illnesses, jalapenos "simply were not on the menu," Tauxe said. "We are quite sure that neither tomatoes nor jalapenos explain the entire outbreak at this point ... We're presuming that both of them have caused illness."

    The outbreak is not over yet, or even showing any sign of slowing with about 25 to 40 cases being reported a day for weeks now, to a total of 1,017 known cases since the outbreak began on April 10, said Tauxe.

    Illnesses now have been reported in 41 states, the CDC said, while acknowledging that there may be 30 to 40 others that go undiagnosed or unreported.