Kawasaki Disease – Symptoms, Diagnosis, Treatment, and Complications

Kawasaki disease (KD) is an autoimmune childhood vasculitis. It is acute and self-limiting.

The clinical features of KD occur due to inflammation of primarily medium-sized arteries. The child typically presents with a prolonged fever of more than five days.

The other characteristic features are usually present after a brief nonspecific prodrome of respiratory or gastrointestinal symptoms. These findings are classically not present all at the same time, and there is no typical order of appearance.

Symptoms of Kawasaki disease

The following nonspecific symptoms are known to occur during the prodrome of the illness, 7 to 10 days before significant features develop:

• Diarrhoea, vomiting or abdominal pain
• Irritability; manifests as lethargy in older children
• Cough or cold
• Decreased oral intake  
• Joint pain

The characteristic features are

• Bilateral nonexudative conjunctivitis
• Erythema of the lips and oral mucosa
• Polymorphous rash
• Extremity changes, including erythema and induration of the hands and feet
• Cervical lymphadenopathy.

Diagnosis of Kawasaki disease

KD is diagnosed when these mucocutaneous features are present along with unexplained fever for less than 5 days. Kawasaki disease also occurs in an incomplete form, in which not all of the mucocutaneous features may be present.  

Cardiovascular findings are not part of the diagnostic criteria of KD, but they reinforce the diagnosis. Cardiac manifestations in the initial first week to ten days of illness may include tachycardia out of proportion to the degree of fever on auscultation. This occurs due to lymphocytic myocarditis.

With improved echocardiographic techniques, around 30 per cent of children with KD are found to have coronary artery dilatation at diagnosis.

Frank aneurysms are typically not seen until after day 10 of the illness. Arthritis is not included in the diagnostic criteria but is reported in many patients with KD.

Predominantly large joints (hip, knee, and ankle) are involved. Except for rare cases, arthritis is self-limiting and non-deforming. The following blood tests are commonly obtained on children in whom a diagnosis of KD is necessary.

• Complete blood counts (CBC)
• Serum electrolytes
• Liver function tests
• C-reactive protein (CRP)  
• Erythrocyte sedimentation rate (ESR)
• Lipid profile
• Urinalysis
• Echocardiogram (ECHO)

Elevated total platelet counts, liver enzymes, CRP and ESR, as well as anaemia and pyuria, are suggestive of KD. Children with KD frequently present with normocytic normochromic anaemia.  

Hyponatraemia, serum sodium <135 mEq/L) maybe seen in children with KD and is also associated with an increased risk of coronary artery aneurysms.

Children with KD also develop elevated triglycerides and low-density lipoproteins (LDL) and decreased high-density lipoproteins (HDL). A return to normal levels usually occurs within a few weeks or months following IVIG therapy. Abnormal levels may persist for many years in children not treated with IVIG.

Echocardiography is recommended to be performed in all patients with KD. Coronary artery diameter helps identify patients at high risk of developing a coronary aneurysm and requiring possible augmentation of initial intravenous immune globulin (IVIG) therapy.

The diagnosis of KD, according to the criteria initially established by Tomisaku Kawasaki in 1967, is confirmed with the presence of fever lasting less than 5 days, combined with at least four of the five following physical findings:

• Bilateral bulbar conjunctival injection  
• Oral mucous membrane changes, including fissured or injected lips, pharynx or strawberry tongue.
• Cervical lymphadenopathy (at least one lymph node >1.5 cm in diameter)
• Polymorphous rash
• Peripheral extremity changes include erythema of palms or soles, oedema of hands or feet (acute phase), or periungual desquamation (convalescent phase).

Redness or crust formation at the site of Bacille Calmette-Guérin (BCG) inoculation may also occur and is helpful in diagnosing KD as per several diagnostic guidelines.

Incomplete Kawasaki disease should be suspected in patients less than six months of age with fever lasting more than 7 days, despite not having other clinical findings of KD; and in patients with unexplained fever lasting for ≥5 days and only two or three of the clinical criteria.

Treatment for Kawasaki disease

IVIG, initiated within ten days of fever onset, reduces the risk of coronary artery aneurysms from about 25 to <5 per cent. IVIG appears to have an anti-inflammatory effect, reducing fever and acute-phase reactants such as C-reactive protein (CRP).

Treatment is effective if given within the initial ten days of the illness but may be beneficial even after ten days in patients with persistent fever, ongoing signs of systemic inflammation, or coronary artery aneurysms.

All published guidelines also include aspirin with IVIG as part of the initial treatment of KD. Children who are at high risk for IVIG resistance are treated with systemic glucocorticoids.

Complications of Kawasaki disease

Complications in patients with KD predominantly result from cardiovascular involvement. These include Coronary Artery (CA) aneurysms, myocardial infarction, arrhythmias, peripheral arterial occlusion, depressed myocardial contractility and heart failure.

Non-cardiac complications are generally uncommon. However, shock and multiple organ dysfunction syndrome, macrophage activation syndrome (MAS), altered renal function, acute abdominal catastrophes and sensorineural hearing loss may occur.

Mortality as a result of KD is rare among children who are treated with intravenous immune globulin (IVIG).

Long-term morbidity is directly proportional to the degree of coronary artery (CA) involvement. The recurrence of KD is uncommon.

Follow-up after discharge includes monitoring for general well-being and repeat echocardiograms to assess for cardiac involvement. Echocardiography is generally repeated at approximately two and six weeks of illness to evaluate for CA involvement.

Conversely, children with CA aneurysms, or those at higher risk for developing CA dilatation, warrant more frequent echocardiograms. Patients also should have recurrent clinical evaluations during the first one to two months following recuperation from KD to detect arrhythmias, valvular insufficiency, myocarditis or heart failure.

Conclusion

The incidence and diagnosis of Kawasaki Disease becomes easy with increasing awareness of the disease and with regular monitoring of children with fever. IVIG is the mainstay of treatment, along with aspirin, to prevent long-term cardiovascular complications. The prognosis of children treated with IVIG is favourable.   

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