Khloe Kardashian -- Contracts Staph Infection at Lamar's Bedside

Khloe Kardashian contracted a serious staph infection at the hospital where Lamar Odom is laid up, and it's so bad she's had to cancel a portion of her book tour.

Lamar has been hospitalized at Cedars-Sinai Medical Center in L.A. for a month, and Khloe has been a frequent visitor.

We're told Khloe has a lesion on her leg which became incredibly painful. She developed a high fever, swollen glands. She's also sweating profusely with intermittent chills.

One very connected source tells TMZ, "It's so scary. She's so sick."

Khloe cancelled several appearances for her book promotion, tweeting, "I'm sick & dr's orders are that I need to lay low until we narrow down what's wrong."