A urinary tract infection UTI is an infection involving the kidneys, ureters, bladder, or urethra. These are the structures that urine passes through before being eliminated from the body.
The upper urinary tract is composed of the kidneys and ureters. Infection in the upper urinary tract generally affects the kidneys – pyelonephritis causing fever, chills , nausea and vomiting. The lower urinary tract consists of the bladder and the urethra. Infection in the lower urinary tract can affect the urethra (urethritis) or the bladder cystitis.
These infections are much more common in girls and women than in boys and men younger than 50 years of age. The following people may be at increased risk of urinary tract infection: