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Kawasaki disease (KD), an acute febrile illness of childhood,
was described in Japan in 1967 by Dr. Tomasaku Kawasaki as the mucocutaneous
lymph node syndrome.1 A vasculitis of medium-sized vessels,
KD has a predilection for the coronary arteries, and 20% to
25% of untreated children develop coronary artery aneurysms.
Fortunately, a regimen of intravenous immunoglobulin and aspirin
reduces the incidence of coronary artery abnormalities to less than 5%.2 Nonetheless,
KD is a leading cause of acquired heart disease in children in North
America and Japan. Furthermore, the etiology of KD remains elusive,
impeding the development of targeted therapy and diagnostic testing.
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Epidemiology
and Specific Populations at Risk
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The Japanese Ministry of Health has collected epidemiologic data on
Kawasaki disease (KD) since 1970 with nationwide surveys every 2
years. In total, over 225,000 cases of KD were reported in Japan
between 1970 and 2006.3-5 In addition to endemic disease,
3 epidemics of KD occurred in Japan in 1979, 1982, and 1986, with an
incidence of 196.1 KD cases per 100,000 children less than 5 years
of age in 1982, the most severe of the epidemics. Interestingly,
there have been no recent epidemics, but recent surveys have revealed
an increase in the incidence of KD.4,5 The incidence of
KD in Japan from 2005 to 2006 was 184.6 per 100,000 in children
younger than 5 years of age.3 The highest incidence of
KD was in children younger than 1 year of age, with a peak incidence
of 6 to 8 months, and cardiac abnormalities occurred most commonly
in infants and in children older than 4 years.3
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In the United States, Holman et al6 reported a hospitalization
rate for Kawasaki disease (KD) in the United States in 2000 as 17.1
per 100,000 children less than 5 years of age, with a median age
at admission of 2 years. Children of Asian and Pacific Islander
heritage had the highest hospitalization rate at 39 per 100,000
children. A subsequent study of KD in Hawaiian children revealed
an incidence higher than the national findings, with an incidence
of 45.2 per 100,000 children less than 5 years of age from 1996
to 2001.7 Furthermore, that study revealed a striking discrepancy
amongst ethnicities in patients less than 5 years of age, with an
incidence of 35.3 per 100,000 white children and 70.9 per 100,000
Asian and Pacific Islander children residing in Hawaii. The incidence
of KD in Japanese Americans living in Hawaii was 197.7 per 100,000
children, higher than the incidence in Japan during the last epidemic. Siblings
of patients with KD may be at higher risk for developing the disease,8 and
parents of affected children in Japan are twice as likely to have
a history of KD themselves.9 These findings are consistent
with the hypothesis that KD results from unidentified environmental triggers
in genetically susceptible hosts.
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Risk factors for poor ...