Kawasaki Disease

Kawasaki disease ( KD ) is seen worldwide First reported in 1961 by Dr Tomisaku Kawasaki in Japan Seen predominantly in Northeast Asian countries like Japan , S Korea , China and Taiwan where it happens 10-30 times more commonly than in the US or Europe More common in boys Severe cardiac complications are also more significantly over represented in boys Most common cause of acquired heart disease during childhood in most industrialized nations In the UK the disease is seen rarely with an incidence estimated to be 8 per 100 000 children under 5 yrs of age – more common in Asian children from Japan 100 % cases in children , more than 85 % of children are younger than 5 with peak incidence at 18-24 months ( some papers quote a peak incidence at 10-11 months ) Low incidence in 1st 6 months Seasonability- peak incidence in winter and spring months Predisposing factors have been reported inconsistently

Etiology- Etiology is not clear the disease is generally self limiting It is assumed from epidemiology and clinical presentation that an infectious cause is likely but it is not known if the cause is a single unknown agent or groups of closely related agents Rowley et al ( 2018 ) have proposed that KD pathogenesis involves an RNA virus that usually causes asymptomatic infection but KD in a subset of genetically predisposed children Several theories have been postulated as
- immune mediated – bacterial or other toxins actings as superantigens leading to nonselective T cell activation
- role of innate immune system
- impaired immune regulation
- genetic predisposition to respond to multiple triggers in a common pathway

What happens small and medium vessel vasculitis arteries in multiple tissues and organs can be affected during the acute febrile phase ( systemic inflammatory disease ) coronary arteries are particularly susceptible to damage leading cause of acquired heart disease in the developed world coronary artery aneurysms ( CAA ) or coronary artery dilatation can happen within 6 weeks of the onset of illness cardiac complications can happen in 15-25 % of patients if KD is not treated on time pericarditis and myocarditis result from subacute / chronic inflammation which is usually concentrated around coronary arteries children who develop CAA are at increased risk of
- coronary artery thrombosis
- myocardial infarction
- sudden death Other complications include
- macrophage activation syndrome ( 2ary haemophagocytic lymphohistiocytosis )
- SIADH case fatality is < 0.1 % in Japan.

Rare but serious 
cause which can be
 difficult to diagnose from
 other self limiting febrile
 illnesses. No diagnostic
 test for KD. Diagnosis
 is made by 
identifying principal
 clinical
 findings and 
excluding other
 clinically
 similar entities
 with 
known causes
. Fever ( typically high
 39 to 40 degrees ) persisting for atleast 5 days and presence of atleast 4 of
 the following 5 principal features- Erythema and cracking of lips , strawberry tongue , and / or erythema of oral and pharyngeal mucosa , Bilateral bulbar conjunctival injection without exudate , Rash : maculopapular , diffuse erythroderma , or erythema multiforme like rash , Erythema and edema of the hands and feet in acute phase and / or periungual desquamation in subacute phase , Cervical lymphadenopathy ( > 1.5 cm dia ) , usually unilateral.

Clinical features may not all be present at a single point of time and establishing an early diagnosis may not be possible – important to keep KD in the differentials and safety netting

Discussion – The diagnosis of KD can be challenging even for experienced pediatricians. Missing the diagnosis can have serious consequences for the young person. In such a scenario have a low threshold for contacting your local PAU and remember that studies have shown diverse disease patterns and changes of KD symptoms , signs and laboratory findings over decades. Incomplete KD- can be suspected if there is high level of suspicion in children presenting with some of the KD features and evidence of systemic inflammation Many experienced paediatricians who have treated many patients with KD may establish the diagnosis with 3 d of fever in rare cases
 Treatment can be commenced before 5 days in such cases by experts
 Studies have shown that most KD cases would be diagnosed in secondary care and KD is a challenging and difficult diagnosis to make in primary care
 A GP may only see once case within their working lifetime and most children may present initially with only a rash or fever

Differentials – Streptococcal infection as scarlet fever , toxic shock syndrome Staphylococcal infection Viral infections as
- measles
- rubella
- roseola infantum
- EBV infection
- influenza A & B
- adenovirus Mycoplasma pneumonia If epidemiological risk factors present 
- Rocky Mountain spotted fever
- other rickettsial infections
- Leptospirosis. hypersensitvity syndrome as Steven- Johnson syndrome and drug hypersensitivityaseptic meningitis mercury poisoning autoimmunre disorders such as systemic juvenile idiopathic arthritis.

under the guidance of specialist paediatric units involves using intravenous immunoglobulin together with aspirin aim is to reduce inflammation and arterial damage and to prevent thrombosis follow ups can include
- repeat echocardiograms

cardiac imaging is critical part of the evaluation of all suspected KD patients 

- ecg
- serology
- cardiology input
- decision about vaccinations
- addressing any potential complications
- decisions on long term follow up.

References

1. Diagnosis, Treatment, and Long-Term Management
   of Kawasaki Disease A Scientific Statement for Health Professionals From the American Heart
   Association AHA SCIENTIFIC STATEMENT Circulation. 2017;135:e927–e999. DOI: 10.1161/CIR.0000000000000484 April 25, 2017 e927
2. Recognising Kawasaki disease in UK
   primary care: a descriptive study using the Clinical Practice Research Datalink Abigail Moore, Anthony Harnden and Richard Mayon-White British Journal of general practice, August 2014
3. Reality of Kawasaki disease epidemiology
   Gi Beom Kim, MD, PhD
   Department of Pediatrics, Seoul National University Children’s Hospital, Seoul National University College of Medicine, Seoul, Korea Reality of Kawasaki disease epidemiology
   Gi Beom Kim, MD, PhD
   Department of Pediatrics, Seoul National University Children’s Hospital, Seoul National University College of Medicine, Seoul, Korea
4. The Epidemiology and Pathogenesis
   of Kawasaki Disease
   Anne H. Rowley* and Stanford T. Shulman*
   Department of Pediatrics, Northwestern University Feinberg School of Medicine, The Ann & Robert H. Lurie Children’s
   Hospital of Chicago, Chicago, IL, United States Frontiers in Pediatrics Dec 2018
5. Kawasaki’s Disease – Guidelines for the Diagnosis and
   Management April 2016 Alder Hey Children’s NHS Foundation Trust
6. Kawasaki disease: a comprehensive review
   Kamleshun Ramphul1
   , Stephanie Gonzalez Mejias2
   Arch Med Sci Atheroscler Dis. 2018; 3: e41–e45.

   Published online 2018 Mar 21. doi: 10.5114/amsad.2018.74522
   PMCID: PMC6374576 PMID: 30775588
7. Kawasaki Disease Clinical Guideline
   November 2, 2016 Dell children medical center of central texas