TABLE 60.5 FEVER AND JOINT PAIN Usually febrile at presentation Septic arthritis (bacterial) Osteomyelitis Gonococcal arthritis Acute rheumatic fever Juvenile idiopathic arthritis (systemic onset subcategory) Subacute bacterial endocarditis Serum sickness Kawasaki disease May or may not be febrile at presentation Leukemia Mycobacterial arthritis Postinfectious (reactive) arthritis Lyme disease Systemic lupus erythematosus Inflammatory bowel disease Joint involvement with Lyme disease has two distinct patterns In early localized or disseminated disease, the child may develop episodic migratory polyarthritis, affecting mainly large joints However, more typically at this stage, the child has polyarthralgia without signs of joint inflammation Weeks to months (mean to weeks) after the tick bite, half of untreated children develop a monoarthritis, usually of the knee The joint is significantly swollen but only mildly painful, and patients are usually afebrile at this stage and without a history of trauma A recent study of children in a Lyme-endemic area found that an absolute neutrophil count