Aim Kawasaki disease (KD) is an acute self-limiting vasculitis predominantly affecting infants and children aged 6 months to 5 years with a peak at age 9–11 months. It is the most common cause of acquired heart disease in young children. The authors sought to determine the factors associated with diagnosis and outcome in infants of less than 6 months of age.

Method The clinical and laboratory data of seven KD patients aged 6 month or under identified between 2000 and 2009 were reviewed.

Results The mean age at diagnosis was 4 months (9 weeks–6 months); five were male, two female. Five were Caucasian, two Asian. Three had fever for more than 7 days before diagnosis (5–21 days). On presentation five patients had raised white cell counts (9.5–27.4× 10⁹) and all had elevated C-reactive protein (48–259 mg/l). By day 9 of illness, all had high platelets (515–1058×10⁹). Four presented as incomplete KD with <4 classical features. Treatment for all patients was initially intravenous immunoglobulin (IVIG) and high dose aspirin. All patients developed cardiac abnormalities. One patient was refractory to IVIG and subsequent high-dose methyl prednisolone with fevers persisting until a single dose of infliximab (5 mg/kg) was given. Regression of coronary artery abnormalities was seen in all patients at long-term follow-up.

Conclusion Despite treatment with IVIG, all of the infants in this cohort developed coronary artery abnormalities, a distinct difference from the expected figure of 5% with IVIG treatment. Over half presented with incomplete KD. The authors highlight the importance of early recognition and prompt treatment of KD in this young age group who are notably more difficult to diagnose but possibly at greater risk of coronary involvement.