Kawasaki Disease

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KD is a vasculitis of unknown etiology that is characterized by multisystem involvement and inflammation of small to medium-sized arteries with resulting aneurysm formation.

The cause of the illness remains unknown, but clinical and epidemiologic features strongly support an infectious origin.
One hypothesis is that a ubiquitous agent causes Kawasaki disease and that symptomatic illness occurs only in genetically predisposed hosts.
The infrequent occurrence of the illness in infants younger than 4 mo may be due to passive maternal antibody, and the virtual absence of cases in adults may be due to widespread immunity.

Can affect children of all races, but more common among children of Asian descent.
Most common in children younger than age 5, with a peak between ages 2 and 3 years, and is rare in children older than age 7.
A seasonal variability has been described with a peak between February and May

Kawasaki disease causes a severe vasculitis of all blood vessels but predominantly affecting the medium-sized arteries, with predilection for the coronary arteries.
In the acute or subacute stages - edema of endothelial and smooth muscle cells with intense inflammatory infiltration of the vascular wall, initially by polymorphonuclear cells but rapidly changing to macrophages, lymphocytes, and plasma cells. IgA plasma cells are prominent in the inflammatory infiltrate.
In the most severely affected vessels, inflammation involves all three layers of the vascular wall, with destruction of the internal elastic lamina. The vessel loses its structural integrity and weakens, resulting in dilatation or aneurysm formation.
Thrombi may form in the lumen and obstruct blood flow.
In the healing phase, the lesion becomes progressively fibrotic, with marked intimal proliferation, which may result in stenotic occlusion of the vessel over time. Those are the major factors leading to coronary disease.

The clinical course of KD can be divided into three phases, each with its own unique manifestations. Aneurysmal involvement of the coronary arteries is the most important manifestation of KD.

Acute Phase

(1 to 2 weeks)
Sudden onset of a high, hectic fever (≥40°C) without an apparent source.
The onset of fever is followed by conjunctival erythema; mucosal changes, including dry, cracked lips and a strawberry tongue; cervical lymphadenopathy; and swelling of the hands and feet. The conjunctivitis is bilateral and nonsuppurative.
A rash, which can vary in appearance, occurs in 80% of children with KD and may be particularly accentuated in the inguinal area and on the chest.
Extreme irritability is prominent, especially in infants.
Abdominal pain and hydrops of the gallbladder, CSF pleocytosis, and arthritis, particularly of medium-sized to large joints, can arise.
Carditis in the acute phase may be manifested by tachycardia, shortness of breath, or overt congestive heart failure. Giant coronary artery aneurysms, which are rare but occur most commonly in very young children, can appear during this phase.

Subacute Phase

Lasts until about the fourth week
Gradual resolution of fever (if untreated) and other symptoms. Desquamation of the skin, particularly of the fingers and toes, appears at this point.
The platelet count, previously normal or slightly elevated, increases to a significant degree (often >1 million/mm3).
This phase heralds the onset of coronary artery aneurysms, which usually appear in the subacute and convalescent phases, and pose the highest risk of sudden death.

Convalescent Phase

The convalescent phase begins with the disappearance of clinical symptoms and continues until the ESR returns to normal, usually 6 to 8 weeks after the onset of illness.
Beau lines of the fingernails may appear during this phase.

Blood cultures
Urine cultures
Chest x-ray.
In the acute phase parameters are elevated, including WBC count, platelet count, and the ESR, which can be profoundly elevated (often >80 mm/hr).
A lumbar puncture-may show pleocytosis.
Tests of hepatobiliary function may be abnormal. Greatly elevated platelet counts develop during the subacute phase.
Two-dimensional echocardiograms, usually during the acute phase, at 2 to 3 weeks, and at 6 to 8 weeks. More frequent echocardiograms and, potentially, coronary angiography are indicated for patients who develop coronary artery abnormalities.

Criteria for Diagnosis of Kawasaki Disease

Fever of ≥5 days' duration associated with at least 4* of the following 5 changes

Bilateral nonsuppurative conjunctivitis
One of more changes of the mucous membranes of the upper respiratory tract, including

pharyngeal injection,
dry fissured lips,
injected lips, and
“strawberry” tongue

One or more changes of the extremities, including

peripheral erythema,
peripheral edema,
periungual desquamation, and
generalized desquamation

Polymorphous rash, primarily truncal
Cervical lymphadenopathy >1.5 cm in diameter

Disease cannot be explained by some other known disease process.

A diagnosis of Kawasaki disease can be made if fever and only 3 changes are present in conjunction with coronary artery disease documented by two-dimensional echocardiography or coronary angiography.

IV immunoglobulin (IVIG) is the mainstay of therapy. A single dose of IVIG (2 g/kg over 12 hours) results in rapid defervescence and resolution of clinical illness in most patients and more importantly reduces the incidence of coronary artery aneurysms in patients with KD.
Aspirin - initially given in anti-inflammatory doses (80 to 100 mg/kg/day q 6 hourly) in the acute phase.
When the fever has resolved for at least 48 hours, the dose of aspirin is decreased to antithrombotic doses (3 to 5 mg/kg/day as a single dose). This dose is continued through the subacute and convalescent phases, usually for 6 to 8 weeks, until follow-up echocardiography fails to show the presence of coronary artery aneurysms.
Approximately 3% to 5% of children with KD initially fail to respond satisfactorily to IVIG therapy. Most of these patients respond to retreatment with IVIG (2 g/kg over 12 hours).
Corticosteroids may have a role during the acute phase if active carditis is apparent and for children with persistent fever after two doses of IVIG.

Coronary artery thrombosis
Peripheral artery aneurysm
Coronary artery aneurysms
Myocardial infarction
Myopericarditis
Congestive heart failure
Hydrops of gallbladder
Aseptic meningitis
Irritability
Arthritis
Sterile pyuria (urethritis)
Thombocytosis (late)
Diarrhea
Pancreatitis
Peripheral gangrene

Infectious
Scarlet fever
Epstein-Barr virus
Adenovirus
Meningococcemia
Measles
Rubella
Roseola infantum
Staphylococcal toxic shock syndrome
Scalded skin syndrome
Toxoplasmosis
Leptospirosis
Rocky Mountain spotted fever
Inflammatory
Juvenile rheumatoid arthritis (systemic onset)
Polyarteritis nodosa
Behçet syndrome
Hypersensitivity
Drug reaction
Stevens-Johnson syndrome (erythema multiforme)

IVIG reduces the prevalence of coronary artery disease from 20% to 25% in children treated with aspirin alone to 2% to 4% in children treated with IVIG and aspirin.
Other than the risk for persistent coronary artery aneurysms, KD has an excellent prognosis.
Risk factors for development of coronary artery aneurysms include

Prolonged fever,
Prolonged elevation of inflammatory parameters such as the ESR,
Age younger than 1 year,
Male gender.

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