Kawasaki disease is an acute febrile vasculitis that occurs in early childhood. It is recognized worldwide, although the greatest number of cases is in Japan. The most notable symptom is prolonged fever with abrupt onset and greater irritability than would be expected given the degree of fever. Non specific symptoms, such as irritability, vomiting, cough, diarrhea, weakness, abdominal pain and joint pain precede the onset of fever for a few days.
The clinical course is divided into three stages – acute, subacute and convalescent. The acute phase begins with an abrupt onset of fever and lasts 7-14 days. The fever tends to peak to 102-104* F and is not responsive to antibiotics and antipyretics. Most of the classic manifestations of Kawasaki disease, such as anterior uveitis, nonexudative bilateral conjunctivitis, perianal erythema, strawberry tongue and lip fissures, myocarditis and pericarditis, and lymphadenopathy occur during this stage. The mucocutaneous changes and lymphadenopathy are most evident during this stage but erythema and edema of the hands and feet may develop later. The diagnosis of Kawasaki disease is made in this stage.
The subacute phase stage begins when the fever has come down and lasts until week 4-6. This stage is characterized by desquamation of the digits, thrombocytosis, and the most dangerous consequence of Kawasaki disease – the development of coronary artery aneurysms. The risk for sudden death is highest in the subacute phase.
The convalescent phase usually occurs within 3 months of presentation and is marked by complete resolution of clinical signs of the illness. Acute phase reactants and other lab abnormalities begin to return to baseline levels. However, cardiac abnormalities may still be present. While smaller coronary artery aneurysms tend to resolve on their own, larger aneurysms may expand and cause a myocardial infarction.
The diagnosis of Kawasaki disease is based on clinical findings. The diagnostic criteria according to the American Heart Association is fever lasting longer than 5 days and 4 of the following 5 clinical findings:
- Reddening of plasma and soles followed by desquamation
- Polymorphous rash
- Strawberry tongue, erythema or fissuring of the lips
- Nonexudative conjunctivitis
- Nonpurulent cervical lymphadenopathy, usually unilateral
There is no specific laboratory test to diagnose Kawasaki disease but acute-phase reactants such as ESR, CRP and alpha-1 antitrypsin levels are almost universally elevated at first and return to baseline 6-10 weeks after the onset of the illness. Levels of antineutrophil cytoplasmic antibodies, antiendothelial cell antibodies, antinuclear antibody and rheumatoid factors are all within the reference range. Culture tests and rapid antigen tests are negative. These tests can help narrow the differential diagnosis.
The treatment goal of Kawasaki disease is to prevent coronary artery aneurysms and to relieve symptoms. Full doses of IVIG are administered and the patient is monitored closely. Although Aspirin is contraindicated in pediatric populations, it is recommended for Kawasaki disease. High dose aspirin is used in the beginning of treatment, followed by lower dose aspirin for its antiplatelet effects. Kawasaki disease that is resistant to IVIG may benefit from intravenous plus corticosteroid therapy or infliximab infusion.
Patients must be monitored within 1 week of hospital discharge and have a repeat echocardiograph 21-28 days after the onset of fever. If baseline echos and echos at 3-4 weeks do not show any evidence of coronary aneurysms, further testing is usually not indicated. Patients with coronary aneurysms should remain on aspirin until the abnormalities resolve.