Roseola, also known as sixth disease, is an infectious disease caused by certain types of human herpes viruses. Most infections occur before the age of three. Symptoms vary from absent to the classic presentation of a fever of rapid onset followed by a rash. The fever generally lasts for three to five days, while the rash is generally pink and lasts for less than three days. Complications may include febrile seizures, with serious complications being rare.It is caused by human herpesvirus 6 (HHV-6A, HHV-6B) or human herpesvirus 7 (HHV-7). Spread is usually through the saliva of those who are otherwise healthy. However, it may also spread from the mother to baby during pregnancy. Diagnosis is typically based on symptoms and does not need to be confirmed with blood tests (PCR or antigen). Low numbers of white blood cells may also be present.Treatment includes sufficient fluids and medications to treat the fever. Nearly all people are infected at some point in time. Males and females are affected equally often. The disease may reactivate in those with a weakened immune system and may result in significant health problems.The disease was first described in 1910 while the causal virus was determined in 1988. The name "sixth disease" comes from its place on the standard list of rash-causing childhood diseases, which also includes measles (first), scarlet fever (second), rubella (third), Dukes disease (fourth, but is no longer widely accepted as distinct from scarlet fever), and erythema infectiosum (fifth).
Risk is increased in the following situations:
Mechanical: any structural abnormalities in the urinary tract, vesicoureteral reflux (urine from the bladder flowing back into the ureter), kidney stones, urinary tract catheterization, ureteral stents or drainage procedures (e.g., nephrostomy), pregnancy, neurogenic bladder (e.g., due to spinal cord damage, spina bifida or multiple sclerosis) and prostate disease (e.g., benign prostatic hyperplasia) in men
Constitutional: diabetes mellitus, immunocompromised states
Behavioral: change in sexual partner within the last year, spermicide use
Positive family history (close family members with frequent urinary tract infections)

Diagnosis
Laboratory examination
Analysis of the urine may show signs of urinary tract infection. Specifically, the presence of nitrite and white blood cells on a urine test strip in patients with typical symptoms are sufficient for the diagnosis of pyelonephritis, and are an indication for empirical treatment. Blood tests such as a complete blood count may show neutrophilia. Microbiological culture of the urine, with or without blood cultures and antibiotic sensitivity testing are useful for establishing a formal diagnosis, and are considered mandatory. Imaging studies
If a kidney stone is suspected (e.g. on the basis of characteristic colicky pain or the presence of a disproportionate amount of blood in the urine), a kidneys, ureters, and bladder x-ray (KUB film) may assist in identifying radioopaque stones. Where available, a noncontrast helical CT scan with 5 millimeter sections is the diagnostic modality of choice in the radiographic evaluation of suspected nephrolithiasis. All stones are detectable on CT scans except very rare stones composed of certain drug residues in the urine.