The diagnosis of Kawasaki disease cannot be made by a single test. There is no true diagnostic laboratory test available. A physician will make the diagnosis after carefully examining the child searching for evidence of at least four of the five clinical features, reviewing a laboratory workup and eliminating the possibilities of other diseases that can cause similar symptoms. Kawasaki disease can be diagnosed as classic or typical when a child has had a fever and at least four of the clinical features in combination with changes in the laboratory blood tests, such as an elevated erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) tests.
However, a diagnosis of atypical or incomplete Kawasaki disease can also be made if a child has a fever plus fewer than four of the clinical features, together with other criteria. This is often extremely difficult to diagnose and may result in overdiagnosis or underdiagnosis of Kawasaki disease.
The following are the main features of Kawasaki disease:
- Fever and irritability often occur first in Kawasaki disease. The fever fluctuates from moderate (101–3° F) to high (104° F). The fever can continue to rise and fall for as long as three weeks if not treated.
- Rash usually develops early in the illness on the chest, back, diaper area and abdomen. In some cases, the rash may spread to the face, arms and legs. Often bright red in appearance, the rash usually consists of poorly defined spots and blotches of various sizes, but sometimes has other appearances.
- Swelling and redness in the hands and feet may occur. Occasionally, swollen and painful joints (knees, hips, ankles or fingers) or a stiff neck will develop. Skin peeling beginning around the fingernails or toenails may occur around 14–21 days.
- Blood-shot eyes may develop, as well as sensitivity to light. There is usually no drainage from the eyes.
- Irritation and inflammation of the lips may develop, and they appear red, dry, swollen or cracked. The inside of the mouth may become more red than usual. The tongue may be coated, slightly swollen and red and is often described as a “strawberry tongue.”
- Swelling of the lymph glands in the neck may be seen, usually limited to one side of the neck. This is the least common of the major clinical features of Kawasaki disease.
Other complaints can include abdominal pain, vomiting, diarrhea, cough, listlessness and irritability.
Therapy requires that your child be hospitalized for intravenous immunoglobulin (IVIG) treatment administered through an IV. IVIG is given with high doses of aspirin early in the illness. After the start of IVIG and aspirin therapy, a large majority of children show improvement within 24 hours. Fever resolves, rash fades and lymph nodes return to their original size. In some children, joint pain and swelling persist after other symptoms have disappeared. If your child experiences prolonged fever, a second dose of IVIG or other medications may be recommended, which usually causes the fever to subside. Your child will be ready for discharge when the fever subsides for 24 hours.
Around the 14th day of illness, your child’s aspirin dose is lowered; this therapy thins the blood slightly to prevent small clots from forming and potentially sticking to the walls of the coronary arteries. Two to three weeks after the first symptoms appear, your child may experience peeling of the skin around the fingernails, toenails, hands and feet. In younger children, the skin may also peel in the diaper area. Some children may develop lines or ridges on the fingernails and toenails, which is known as Beau's lines. This is another common characteristic of Kawasaki disease and is only visible until the nails grow out.
Most children with Kawasaki disease are able to return to their normal activity after discharge from the hospital. A child's temperament, as well as eating and sleeping habits, may take longer to return to normal. Children will be monitored by our team for a minimum of one year following the onset of illness, with follow-up outpatient visits. Children with heart complications will require more frequent or prolonged follow-up care.