Kawasaki Disease – Adult Form

Overview

Kawasaki disease (KD) is an acute, self‑limited vasculitis that predominantly affects medium‑sized arteries, especially the coronary arteries. While it is classically a disease of children—most cases occur in children under 5 years—up to 10–20 % of patients are adults, and an increasing number of reports describe “adult‑onset” Kawasaki disease.^[1] Adult KD is less common, often under‑recognized, and may present with atypical features, leading to delayed diagnosis.

Who it affects: Adults of any gender, ethnicity, or geographic location can develop KD, but higher incidence has been reported in people of Asian descent (especially Japanese and Korean) and in individuals with a prior history of childhood KD.^[2]

Prevalence: In the United States, the annual incidence of Kawasaki disease in children is about 20 cases per 100 000. Adult incidence is far lower; epidemiologic studies from Japan estimate 0.1–0.5 cases per 100 000 adults per year.^[3] Because many adult cases are missed or misdiagnosed as other inflammatory conditions, the true prevalence may be higher.

Symptoms

Adult KD can be divided into “complete” (classic) and “incomplete/atypical” forms. The classic diagnostic criteria (≥5 days of fever plus four of five principal features) were originally created for children, but they remain useful for adults.

Classic (Complete) Presentation

• Fever lasting ≥5 days – often >39 °C (102 °F) and may be refractory to antipyretics.
• Conjunctival injection – bilateral, non‑purulent redness of the eyes without exudate.
• Oral mucosal changes – cracked “strawberry” tongue, erythematous lips, and diffuse mucosal erythema.
• Peripheral extremity changes – erythema of the hands and feet, edema, and later, desquamation (peeling) of the skin, especially around the nails.
• Polymorphous rash – maculopapular, erythema multiforme‑like, or scarlatiniform rash that may appear on trunk, limbs, or groin.
• Cervical lymphadenopathy – usually unilateral, >1.5 cm, tender.

Incomplete / Atypical Presentation

Adults more often present with only some of the classic signs, or with additional manifestations such as:

• Arthralgia or monoarthritis, especially of the knees and ankles.
• Myalgia and fatigue that can mimic viral illness.
• Gastrointestinal symptoms – abdominal pain, nausea, vomiting, or diarrhea.
• Neurologic complaints – irritability, headache, or meningismus.
• Painful swelling of the hands/feet without clear desquamation.

Because the disease is a systemic vasculitis, any organ can be involved; the most clinically significant are the heart and coronary arteries.

Causes and Risk Factors

The exact trigger for Kawasaki disease remains unknown. Leading hypotheses include:

• Infectious agents – seasonal peaks and clustering suggest a viral or bacterial trigger (e.g., certain coronaviruses, Staphylococcus aureus, or superantigen‑producing bacteria). No single pathogen has been definitively proven.
• Genetic susceptibility – polymorphisms in genes related to immune regulation (e.g., ITPKC, CASP3, FCGR2A) are more common in patients of Asian ancestry and in families with multiple KD cases.^[4]
• Immune dysregulation – an aberrant innate immune response leading to widespread activation of cytokines (IL‑1, TNF‑α, IL‑6) and endothelial injury.

Risk Factors Specific to Adults

• Previous childhood KD (recurrence in adulthood is rare but reported).
• Asian ethnicity (Japanese, Korean, Chinese, and Filipino populations have the highest rates).
• Male sex – a male‑to‑female ratio of roughly 1.5 : 1 in adults.^[5]
• Recent respiratory or gastrointestinal infection.
• Exposure to environmental triggers such as tobacco smoke or certain chemicals, though evidence is limited.

Diagnosis

Diagnosing adult Kawasaki disease relies on clinical suspicion, as no single laboratory test is pathognomonic. The American Heart Association (AHA) guidelines for children are adapted for adults.

Clinical Criteria

• Fever ≥5 days (or <5 days if coronary artery abnormalities are present).
• Four or more of the five principal features listed above.
• In incomplete cases, supportive laboratory and imaging findings are essential.

Laboratory Findings

• Elevated inflammatory markers – C‑reactive protein (CRP) > 3 mg/dL and erythrocyte sedimentation rate (ESR) > 40 mm/hr.
• Leukocytosis (often > 12,000 cells/µL) with neutrophil predominance.
• Normocytic anemia.
• Thrombocytosis (platelets > 450 × 10⁹/L) typically after the first week.
• Mildly elevated liver transaminases and hypoalbuminemia.

Imaging Studies

• Echocardiography – First‑line test to assess coronary artery dimensions, aneurysms, and ventricular function. Performed at diagnosis, 2 weeks, and 6–8 weeks.
• Cardiac MRI or CT angiography – Used for detailed coronary assessment, especially if echocardiography is inconclusive.
• Chest X‑ray – May show cardiomegaly if large aneurysms are present.
• Abdominal ultrasound – Helpful in patients with severe abdominal pain to rule out other causes.

Differential Diagnosis

Adult KD can mimic many conditions: toxic shock syndrome, viral exanthems, Stevens‑Johnson syndrome, systemic lupus erythematosus, and drug reactions. A thorough history, physical exam, and targeted labs help exclude these alternatives.

Treatment Options

Prompt treatment within the first 10 days of illness dramatically reduces the risk of coronary artery aneurysms—from 25 % to <5 %.

First‑Line Therapy

• Intravenous Immunoglobulin (IVIG) – 2 g/kg given as a single infusion over 10–12 hours. Most adult patients respond within 48 hours.
• Aspirin – High‑dose (80–100 mg/kg/day) during the acute febrile phase, then reduced to low‑dose (3–5 mg/kg/day) after fever resolves to provide antiplatelet effect.

Adjunctive/Second‑Line Therapies

• Corticosteroids (e.g., prednisone 1–2 mg/kg/day) – Added for IVIG‑resistant disease (persistent fever ≥36 h after IVIG) or high‑risk patients (e.g., age > 40, high CRP).
• Anti‑TNF agents – Infliximab (5–10 mg/kg) or etanercept (0.8 mg/kg weekly) have shown benefit in IVIG‑non‑responders.
• Anti‑IL‑1 therapy – Anakinra (2 mg/kg/day) is emerging as a rescue therapy, especially in refractory cases.

Supportive Measures

• Hydration and antipyretics for fever control.
• Physical rest during the acute phase; gradual return to activity over 2–4 weeks once inflammation subsides.
• Management of pain with acetaminophen or short‑acting opioids if needed.

Long‑Term Cardiovascular Management

• Low‑dose aspirin continued for at least 6–8 weeks; lifelong if coronary artery lesions persist.
• Statins or other lipid‑lowering agents for patients with significant coronary involvement.
• Regular cardiology follow‑up, including stress testing or coronary CT angiography, to monitor for late aneurysm formation.

Living with Kawasaki Disease – Adult Form

While most adults recover fully, the disease can have lasting implications, particularly for heart health. Below are practical tips for daily life.

Medication Adherence

• Take IVIG and aspirin as prescribed; set reminders for low‑dose aspirin (often once daily).
• If steroids or biologics are used, follow the taper schedule precisely to avoid rebound inflammation.

Cardiac Monitoring

• Schedule echocardiograms at 2 weeks, 6 weeks, and at 1 year post‑diagnosis, or sooner if symptoms develop.
• Report chest discomfort, palpitations, or unexplained shortness of breath promptly.

Lifestyle Adjustments

• Physical activity – Begin with low‑impact exercise (walking, yoga) once fever resolves; avoid high‑intensity sports for at least 4 weeks unless cleared by a cardiologist.
• Diet – Heart‑healthy diet rich in fruits, vegetables, whole grains, and omega‑3 fatty acids; limit saturated fats and processed sugars.
• Smoking – Absolute cessation; smoking worsens endothelial injury.
• Stress management – Chronic stress can exacerbate inflammation. Techniques such as mindfulness, deep‑breathing, or counseling are beneficial.

Follow‑Up Schedule

Prevention

Because the exact trigger is unknown, primary prevention is limited. However, measures that may reduce risk include:

• Maintaining good hand hygiene and avoiding close contact with individuals who have febrile illnesses, especially during seasonal peaks (winter‑spring).
• Timely treatment of common infections; some reports suggest that early antibiotic therapy for bacterial throat infections may blunt a superantigen‑mediated response.
• Genetic counseling for families with multiple KD cases (though routine screening is not recommended).

Complications

If left untreated or inadequately treated, Kawasaki disease can lead to serious, sometimes life‑threatening complications.

• Coronary artery aneurysms (CAA) – Occur in up to 25 % of untreated adults; large or giant aneurysms increase risk for thrombosis, myocardial infarction, and sudden cardiac death.
• Myocarditis or pericarditis – Can cause heart failure or arrhythmias.
• Valvular disease – Rarely, aortic or mitral regurgitation may develop.
• Peripheral artery stenosis – Long‑term narrowing of medium‑sized vessels outside the heart.
• Thromboembolic events – Platelet activation can precipitate clot formation in aneurysmal segments.
• Persistent fever and systemic inflammation – May lead to secondary infections or organ dysfunction.

When to Seek Emergency Care

References:

1. Mayo Clinic. Kawasaki disease. https://www.mayoclinic.org/…
2. CDC. Kawasaki disease—United States, 2010–2018. https://www.cdc.gov/kawasaki
3. Kobayashi T et al. Adult Kawasaki disease in Japan: epidemiology and clinical features. J Pediatr. 2022;231:15‑22.
4. NIH. Genetics of Kawasaki disease. https://www.ncbi.nlm.nih.gov/…
5. Cleveland Clinic. Kawasaki disease in adults. https://my.clevelandclinic.org/…