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Kawasaki disease is a short illness of early childhood in which blood vessels throughout the body become inflamed. It causes several days of high fever along with a rash, red eyes, red lips and swollen hands and feet. The illness itself passes, but in some children the inflammation weakens the coronary arteries — the vessels supplying the heart muscle — and they can balloon out into an aneurysm. Treatment given within the first ten days greatly reduces that risk, which is why recognising it early matters more than almost anything else about it.
Definition
Kawasaki disease is an acute vasculitis — an inflammation of blood vessels — that affects medium-sized arteries, with a particular tendency to involve the coronary arteries. It occurs almost entirely in children, most often under five years of age.1 It was first described in Japan in 1967 by the paediatrician whose name it carries.2
It is now the leading cause of acquired heart disease in children in Australia and other high-income countries, having overtaken acute rheumatic fever in most of the population.1,11 Rheumatic heart disease remains far more common in Aboriginal and Torres Strait Islander communities, so the two conditions are not interchangeable in a Central Queensland setting.
The cause is not known. The pattern of the illness — seasonal peaks, occasional geographic clusters, an age range that spares the first few months of life — points to an infectious or environmental trigger acting on a genetically susceptible child, but no organism has been consistently identified.1
Pathophysiology
Detailed pathological study has shown that the arterial damage occurs in three linked processes rather than one.5
Necrotising arteritis
In the first two weeks, neutrophils destroy the wall of the artery from the inside outwards. This is a self-limited process — it stops within roughly a fortnight — but any aneurysm that forms does so during this window.5 It is the reason the treatment deadline is measured in days.
Subacute and chronic vasculitis
A second process, driven by lymphocytes and other immune cells, begins in the same period but can continue for months or years. It affects the arteries that were damaged initially.5
Luminal myofibroblastic proliferation
Smooth-muscle-derived cells then proliferate inside the vessel, progressively narrowing it. This is the process behind the late narrowing and blockage that can occur years after the original illness, and it explains why a child who recovers well still needs long-term cardiology follow-up if the arteries were involved.5,10
Symptoms
The illness is defined by fever lasting five days or more together with the principal clinical features:1
- Red eyes without discharge (bilateral conjunctival injection).
- Changes to the lips and mouth — cracked red lips, a strawberry-red tongue, a diffusely red throat.
- Rash, variable in appearance, usually over the trunk.
- Changes to the hands and feet — swelling and redness of the palms and soles early, followed in the second or third week by peeling skin, often starting around the fingertips.
- A swollen neck gland, usually a single node on one side and often the least reliable of the features.
Children are typically very irritable — more so than the temperature alone would explain — and this is one of the details parents and clinicians remember most.
Incomplete Kawasaki disease describes a child with prolonged fever but too few of the features to meet the full criteria. It is more common in infants under one year, who are also at the highest risk of coronary complications, so a prolonged unexplained fever in a baby warrants specific consideration of the diagnosis rather than watchful waiting.1
Diagnosis
There is no blood test that confirms Kawasaki disease. The diagnosis is clinical, made against published criteria and supported by investigations that raise or lower suspicion.1
- Blood tests show marked inflammation — a high CRP and ESR, anaemia, and a rising platelet count in the second week. Low albumin and low sodium are associated with more severe disease.1
- Echocardiography is performed at diagnosis and repeated during follow-up. Coronary artery dimensions are reported as a Z-score — how far the measurement sits from the expected size for a child of that body surface area — because absolute millimetres are meaningless in a growing child.1,8
- Exclusion of other causes of prolonged fever, including viral illnesses, scarlet fever and drug reactions.1
Since 2020, a similar multisystem inflammatory illness in children has been recognised following SARS-CoV-2 infection. It overlaps with Kawasaki disease but tends to affect older children, more often causes heart-muscle dysfunction and shock, and is managed differently.12
Management
Treatment is urgent, hospital-based, and highly effective when given in time.
- Intravenous immunoglobulin (IVIG), a single infusion of 2 g/kg, ideally within ten days of fever onset and as soon as the diagnosis is made. This is the treatment that changed the natural history of the disease: it reduces the rate of coronary artery aneurysms from around a quarter of untreated children to under five per cent.3,4
- Aspirin, at anti-inflammatory dose during the acute illness and then at low antiplatelet dose until the coronary arteries are confirmed normal.1
- Additional treatment for resistant disease. Roughly one child in six has persisting or recurrent fever after the first infusion. Options include a second dose of IVIG, corticosteroids, or infliximab.1,6,7 In children identified as high risk at the outset, adding corticosteroids to first-line IVIG reduces coronary abnormalities.6
- Echocardiographic follow-up, with the schedule set by whether and how much the coronary arteries were affected.1
Treatment after day ten is still given if the child is still febrile or has evidence of ongoing inflammation — a late diagnosis is not a reason to withhold it.1
Co-morbidities and complications
- Coronary artery aneurysms, the complication that defines the condition's seriousness. They are graded by Z-score, and giant aneurysms (Z-score ≥10) carry the highest long-term risk of clot formation, narrowing and myocardial infarction.1,8,9
- Myocarditis and valve regurgitation during the acute illness, usually transient.1
- Kawasaki disease shock syndrome — a small number of children present with low blood pressure and require intensive care.1
- Late coronary narrowing, developing years afterwards in vessels that were previously aneurysmal, through the proliferative process described above.5,10
Children whose coronary arteries remain normal throughout are not currently considered to carry a meaningfully increased long-term cardiac risk, although the question of subtler vascular effects remains open.10
Medications
Listed here so that families recognise what has been prescribed and why. Prescribing decisions sit with the treating paediatric cardiology team.
- IVIG — the definitive acute treatment.3,4
- Aspirin — anti-inflammatory then antiplatelet. Kawasaki disease is one of the few situations in which aspirin is deliberately given to a young child, and families are usually advised about influenza and varicella vaccination in that context.1
- Corticosteroids or infliximab — for resistant disease or for children stratified as high risk at presentation.6,7
- Anticoagulation, typically warfarin or low molecular weight heparin alongside aspirin, for children with large or giant aneurysms in whom clot formation is the principal danger.1,9
- Beta blockers and statins are used selectively in those with significant persisting coronary disease.1
Prognosis
For the great majority of children treated promptly, the outlook is excellent and there is no lasting heart involvement.1 Prognosis is determined almost entirely by what happened to the coronary arteries, and this is why follow-up is stratified by maximum Z-score rather than by how unwell the child seemed.1,8
Aneurysms that are small or moderate frequently remodel and return to normal calibre within one to two years, and risk falls with them.8 Giant aneurysms behave differently. They rarely resolve, and three decades of follow-up show a continuing risk of thrombosis, stenosis and cardiac events into adult life, requiring lifelong cardiology care.9,10
Recurrence of the illness itself is uncommon.1
Living with it
For most families the illness is a frightening fortnight followed by an ordinary childhood. Peeling fingers and fatigue can persist for some weeks, and irritability often outlasts the fever.
Where the coronary arteries were affected, three practical questions tend to matter more than any other:
- What sport is allowed? Children with normal coronary arteries need no restriction at all. Restriction applies to those with persisting aneurysms, and particularly to children on anticoagulation, for whom contact and collision sports are usually avoided because of bleeding risk rather than cardiac risk.1
- What happens at adolescence? Cardiovascular risk factors matter more in someone with a damaged coronary artery than in their peers, so smoking, blood pressure, weight and activity are followed more closely.1,10
- Who looks after them as an adult? Transition from paediatric to adult cardiology is a recognised weak point. Adults who had Kawasaki disease as children may present with cardiac symptoms to clinicians unaware of the history, so a written record of the diagnosis and the peak Z-score is genuinely useful to keep.10
Role of the physiotherapist
Most children who have had Kawasaki disease need no physiotherapy at all, and it would be misleading to suggest otherwise. Acute care is medical, and a child whose coronary arteries stayed normal simply returns to normal activity.
Where a cardiorespiratory physiotherapist has a role, it is in the minority with persisting coronary involvement, and in adults carrying the consequences of a childhood illness:
- Turning a cardiology restriction into a practical activity plan. Families are frequently given a limitation without being told what their child can do. Translating a restriction into specific, safe, enjoyable activity is a physiotherapy task, and inactivity carries its own long-term cardiovascular cost.1
- Supervised exercise for those cleared for it. Where cardiology has permitted exercise but the family is anxious, a monitored programme is often what restores confidence — the same principle applied in paediatric cardiac populations more broadly.11,12
- Exercise assessment in adults with a history of Kawasaki disease and residual coronary disease, as part of ordinary cardiac rehabilitation.10
- Advice on return to sport after anticoagulation changes, which is a decision made with the cardiologist and not independently.
We do not clear a child for sport. That decision belongs to the treating paediatric cardiologist, and we work from their written advice. What we can do is make the permitted activity happen.
- Cardiorespiratory Rehabilitation — supervised exercise for those cleared for it, and a way back to confidence after a cardiac scare
- Physiotherapy Assessment — an activity plan built from your cardiologist's written advice
- Functional Capacity Assessments — objective documentation of exercise capacity where it is needed for a plan or a return to work
Acute Kawasaki disease is treated in hospital, and most children need nothing from us afterwards. Where we help is the part families are often left holding: turning a cardiologist's restriction into activity a child can actually do, and rebuilding exercise confidence in older patients with residual coronary disease. We work from your cardiologist's written advice — we do not clear anyone for sport.
Part 1 · References
- McCrindle BW, Rowley AH, Newburger JW, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: a scientific statement for health professionals from the American Heart Association. Circulation 2017;135(17):e927–e999.
- Kawasaki T. Acute febrile mucocutaneous syndrome with lymphoid involvement with specific desquamation of the fingers and toes in children. Arerugi 1967;16(3):178–222.
- Newburger JW, Takahashi M, Burns JC, et al. The treatment of Kawasaki syndrome with intravenous gamma globulin. N Engl J Med 1986;315(6):341–347.
- Newburger JW, Takahashi M, Beiser AS, et al. A single intravenous infusion of gamma globulin as compared with four infusions in the treatment of acute Kawasaki syndrome. N Engl J Med 1991;324(23):1633–1639.
- Orenstein JM, Shulman ST, Fox LM, et al. Three linked vasculopathic processes characterize Kawasaki disease: a light and transmission electron microscopic study. PLoS One 2012;7(6):e38998.
- Kobayashi T, Saji T, Otani T, et al. Efficacy of immunoglobulin plus prednisolone for prevention of coronary artery abnormalities in severe Kawasaki disease (RAISE study): a randomised, open-label, blinded-endpoints trial. Lancet 2012;379(9826):1613–1620.
- Burns JC, Best BM, Mejias A, et al. Infliximab treatment of intravenous immunoglobulin-resistant Kawasaki disease. J Pediatr 2008;153(6):833–838.
- Friedman KG, Gauvreau K, Hamaoka-Okamoto A, et al. Coronary artery aneurysms in Kawasaki disease: risk factors for progressive disease and adverse cardiac events in the US population. J Am Heart Assoc 2016;5(9):e003289.
- Tsuda E, Hamaoka K, Suzuki H, et al. A survey of the 3-decade outcome for patients with giant aneurysms caused by Kawasaki disease. Am Heart J 2014;167(2):249–258.
- Gordon JB, Kahn AM, Burns JC. When children with Kawasaki disease grow up: myocardial and vascular complications in adulthood. J Am Coll Cardiol 2009;54(21):1911–1920.
- Saundankar J, Yim D, Itotoh B, et al. The epidemiology and clinical features of Kawasaki disease in Australia. Pediatrics 2014;133(4):e1009–e1014.
- Whittaker E, Bamford A, Kenny J, et al. Clinical characteristics of 58 children with a pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2. JAMA 2020;324(3):259–269.
Clinical evidence
Part 1 covers the same condition without the technical detail. What follows is the evidence base behind it, written for clinicians — the literature, the reasoning and the gaps.
For clinicians: this summary supports clinical reasoning and is not a protocol. Check current guidelines and local policy before applying it, and read it alongside the key references and guidelines directory.
Framing. Kawasaki disease is a self-limited medium-vessel vasculitis of unknown aetiology, described in Japan in 1967 and now the leading cause of acquired paediatric heart disease in high-income settings.1,2 Australian surveillance data give an incidence of roughly 10 per 100,000 children under five, lower than Japanese rates but with the same age distribution and the same relationship between delayed treatment and coronary outcome.11 The AHA scientific statement remains the reference standard for diagnosis, risk stratification and long-term management, and is the document to work from.1
Diagnosis rests on criteria that were never designed to be sensitive
The classical criteria — fever ≥5 days plus four of five principal features — were derived to define a syndrome, not to catch every case, and incomplete presentations account for a substantial and rising proportion of diagnoses.1 The clinically important asymmetry is that infants under twelve months are both the most likely to present incompletely and the most likely to develop coronary aneurysms.1,8 The AHA algorithm for incomplete disease uses supplementary laboratory criteria and echocardiography to lower the threshold to treat in exactly this group.1
Coronary dimensions must be expressed as body-surface-area-adjusted Z-scores; absolute measurements systematically under-recognise dilatation in small children.1,8
IVIG: the size of the effect, and the ten-day window
Immunoglobulin was shown to reduce coronary abnormalities in the mid-1980s, and the single 2 g/kg infusion was established as superior to divided dosing in 1991.3,4 The reduction — from roughly 25% of untreated children to under 5% treated — is among the larger treatment effects in paediatrics.1,3,4
The ten-day figure is not arbitrary. Histopathology shows that necrotising arteritis is complete within approximately the first two weeks, so the aneurysm-forming process is finished before late treatment can act.5 The corollary matters clinically: treatment beyond day ten is still indicated in the presence of persistent fever or ongoing inflammation, because the second and third pathological processes continue.1,5
Resistant disease and primary intensification
Approximately 10–20% of patients have persistent or recrudescent fever after initial IVIG, and this group carries a materially higher risk of coronary involvement.1 RAISE demonstrated that adding prednisolone to primary IVIG in patients stratified as high risk reduced coronary artery abnormalities, though the risk scores used were derived and validated in Japanese cohorts and perform less well elsewhere.6 Infliximab has been studied for IVIG resistance with evidence of reduced inflammation and acceptable safety.7 The unresolved question is patient selection rather than drug efficacy — there is no well-performing risk score for non-Japanese populations, which is the principal barrier to primary intensification being used more widely.1,6
Long-term outcome is a function of maximum Z-score
Risk stratification and follow-up intensity are driven by peak coronary Z-score rather than by acute severity.1,8 Small and medium aneurysms regress to normal lumen diameter in a substantial proportion within one to two years, though remodelled vessels retain histological abnormality.8 Giant aneurysms (Z ≥10) behave as a separate category: three-decade Japanese follow-up documents continuing thrombotic and stenotic events into adulthood, and these patients require lifelong specialist care.9
Adults presenting with ischaemic events attributable to childhood Kawasaki disease are described and are likely to be under-recognised, because the history is frequently unknown to the treating clinician.10
Physical activity: the evidence is largely extrapolated
There is no Kawasaki-specific trial of exercise training. Recommendations derive from paediatric cardiology consensus on activity in congenital and acquired heart disease, which supports participation for the large majority and reserves restriction for defined haemodynamic or arrhythmic risk.1 For the clinician the practical points are that restriction in this population is usually driven by anticoagulation and bleeding risk rather than by ischaemic risk, and that children with normalised coronary arteries require no restriction at all.1 Where restriction applies, stress testing with myocardial perfusion assessment informs it.1
Overlap with SARS-CoV-2-associated multisystem inflammation
MIS-C shares features with Kawasaki disease but differs epidemiologically and clinically — older median age, higher rates of gastrointestinal presentation, myocardial dysfunction and shock, and more marked lymphopenia.12 It should be treated as a distinct diagnosis rather than a Kawasaki variant, though the acute immunomodulatory approach overlaps.12
What we do not know
- The aetiology. Six decades after description, no trigger has been established, which constrains both prevention and diagnostic testing.1
- Reliable risk stratification outside Japan. Existing scores do not transfer, so primary intensification cannot be targeted confidently in Australian practice.1,6,11
- Whether angiographically normalised arteries are functionally normal. Remodelled vessels show persistent intimal abnormality, and the long-term significance is unsettled.8,10
- Whether structured exercise alters long-term cardiovascular outcome in this population. Plausible and untested; current advice is extrapolated from wider paediatric cardiac practice.1
- Optimal transition to adult services, which is repeatedly identified as a failure point without an evidence-based model to replace it.10
References for the clinical evidence summary
- McCrindle BW, Rowley AH, Newburger JW, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: a scientific statement for health professionals from the American Heart Association. Circulation 2017;135(17):e927–e999.
- Kawasaki T. Acute febrile mucocutaneous syndrome with lymphoid involvement with specific desquamation of the fingers and toes in children. Arerugi 1967;16(3):178–222.
- Newburger JW, Takahashi M, Burns JC, et al. The treatment of Kawasaki syndrome with intravenous gamma globulin. N Engl J Med 1986;315(6):341–347.
- Newburger JW, Takahashi M, Beiser AS, et al. A single intravenous infusion of gamma globulin as compared with four infusions in the treatment of acute Kawasaki syndrome. N Engl J Med 1991;324(23):1633–1639.
- Orenstein JM, Shulman ST, Fox LM, et al. Three linked vasculopathic processes characterize Kawasaki disease: a light and transmission electron microscopic study. PLoS One 2012;7(6):e38998.
- Kobayashi T, Saji T, Otani T, et al. Efficacy of immunoglobulin plus prednisolone for prevention of coronary artery abnormalities in severe Kawasaki disease (RAISE study): a randomised, open-label, blinded-endpoints trial. Lancet 2012;379(9826):1613–1620.
- Burns JC, Best BM, Mejias A, et al. Infliximab treatment of intravenous immunoglobulin-resistant Kawasaki disease. J Pediatr 2008;153(6):833–838.
- Friedman KG, Gauvreau K, Hamaoka-Okamoto A, et al. Coronary artery aneurysms in Kawasaki disease: risk factors for progressive disease and adverse cardiac events in the US population. J Am Heart Assoc 2016;5(9):e003289.
- Tsuda E, Hamaoka K, Suzuki H, et al. A survey of the 3-decade outcome for patients with giant aneurysms caused by Kawasaki disease. Am Heart J 2014;167(2):249–258.
- Gordon JB, Kahn AM, Burns JC. When children with Kawasaki disease grow up: myocardial and vascular complications in adulthood. J Am Coll Cardiol 2009;54(21):1911–1920.
- Saundankar J, Yim D, Itotoh B, et al. The epidemiology and clinical features of Kawasaki disease in Australia. Pediatrics 2014;133(4):e1009–e1014.
- Whittaker E, Bamford A, Kenny J, et al. Clinical characteristics of 58 children with a pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2. JAMA 2020;324(3):259–269.
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