Kawasaki disease

One challenge in diagnosing Kawasaki disease is distinguishing it from other childhood diseases that have similar symptoms, such as some viral infections, including measles, adenovirus, enterovirus and Epstein-Barr virus—as well as illnesses caused by bacterial toxins, such as scarlet fever, toxic shock syndrome or bacterial infection of the lymph nodes in the neck.

A prolonged high fever (at least four days), along with several other symptoms, must be present for your child’s doctor/NP/PA to consider Kawasaki disease as the cause of hisillness—and other illnesses need to be ruled out. To arrive at a diagnosis, your child’s doctor will start by taking a full medical history and conducting a thorough physical exam. Diagnostic tests may include:

• electrocardiogram (ECG or EKG): a test that records the electrical activity of the heart and shows abnormal rhythms (arrhythmias or dysrhythmias)
   
• echocardiogram (cardiac ultrasound): a diagnostic tool that uses sound waves to produce a moving picture of the heart and heart valves in order to:
  • measure the coronary arteries
  • evaluate the structure and function of the heart muscle and heart valves
     
• complete blood count (CBC): a measurement of the size, number and maturity of blood cells in a specific volume of blood; detects elevation in the numbers of white blood cells, which normally multiply in the presence of infection
   
• erythrocyte sedimentation rate (ESR, “sed rate”) and/or c-reactive protein (CRP): non-specific markers of inflammation in the blood
   
• urinalysis: testing of a urine sample for protein, red blood cells or white blood cells; helps rule out other diseases

Observations and lab results that can support a diagnosis of Kawasaki disease include:

• extreme irritability
• inflammation of the joints (arthritis)
• elevated white blood cell count
• elevated liver function tests
• signs of inflammation in the blood and urine
• anemia

Incomplete Kawasaki disease

It is possible to have Kawasaki disease without showing all of these signs. Such cases are called “incomplete” (or atypical) Kawasaki disease. Infants younger than 6 months are most likely to have incomplete Kawasaki disease, and infants have the highest risk for developing coronary artery injury.