Patient Age and the Seasonal Pattern of Onset of Kawasaki's Disease

Kawasaki Disease-Associated Cytokine Storm Syndrome

Kawasaki disease (KD) is a hyperinflammatory syndrome manifesting as an acute systemic vasculitis characterized by fever, nonsuppurative conjunctival injection, rash, oral mucositis, extremity changes, and cervical lymphadenopathy. KD predominantly affects young children and shares clinical features and immunobiology with other hyperinflammation syndromes including systemic juvenile idiopathic arthritis (sJIA) and multisystem inflammatory syndrome in children (MIS-C). Cytokine storm syndrome (CSS) is an acute complication in ~2% of KD patients; however, the incidence is likely underestimated as many clinical and laboratory features of both diseases overlap. CSS should be entertained when a child with KD is unresponsive to IVIG therapy with recalcitrant fever. Early recognition and prompt institution of immunomodulatory treatment can substantially reduce the mortality and morbidity of CSS in KD. Given the known pathogenetic role of IL-1β in both syndromes, the early use of IL-1 blockers in refractory KD with CSS deserves consideration.

Seasonality and geographical distribution of Kawasaki disease among Black children in the Southeast United States

Introduction

Kawasaki Disease (KD) is a leading cause of pediatric acquired heart disease in the United States, affecting up to 7,000 children annually. Seasonal variation, an epidemiological characteristic of KD, has previously been reported predominantly among Asian children; however, little is known about the epidemiology and seasonality of KD of Black children within the U.S.

Methods

Electronic medical records were abstracted from 529 hospitalized KD patients admitted to a single tertiary center in Alabama between 2005 and 2019. Medical charts were reviewed to confirm KD diagnosis following American Heart Association criteria. Cases were stratified by the month of diagnosis date to assess seasonality, and statewide distribution of incidence is reported at county level using geographical spatial analysis. Comparisons were performed between Black patients and White patients with KD.

Results

The average number of KD cases per year was 35. Approximately, 60% were males and 44% were White children (N = 234), 45% were Black children (N = 240) and 11% were other races (N = 55). Black children were younger than White children at KD admission (median age 32 vs. 41 months respectively, p = 0.02). Overall, the highest rates of cases occurred between January and April. When stratifying by race, cases started to rise in December among White children with the highest rates between February and April with a peak in March. Among Black children cases were high during the winter season (January-April) with a peak in April. Similarly high rates also occurred in June, July and November. There were no differences in geographical distribution of cases by race.

Conclusion

KD incidence among White children in Alabama follows a seasonal cycle similar to other regions in the U.S. However, sustained incidence and additional peaks outside of the usual KD seasonality were seen among Black children with KD. Further studies are needed to investigate differential triggers between races.

Seasonal variations in renal biopsy numbers and primary glomerular disease features based on the Japan renal biopsy registry

We analyzed the seasonal variations in the number of renal biopsies and clinical characteristics of primary glomerular disease in Japan using the Japan Renal Biopsy Registry (J-RBR). We retrospectively collected clinical and pathological data of patients with primary glomerular disease who were registered in the J-RBR between 2007 and 2018. Immunoglobulin A nephropathy (IgAN), minimal change nephrotic syndrome (MCNS), membranous nephropathy (MN), and postinfectious acute glomerulonephritis (PIAGN) constituted the four major glomerular disorders included in this study (total, 13,989; IgAN, 9121; MCNS, 2298; MN, 2447; and PIAGN, 123). The number of patients with IgAN or MCNS was higher during summer. However, no overt seasonal variations were observed in patients with MN or PIAGN. Subgroup analyses suggested that in the patients with IgAN, more renal biopsies of severe cases were performed during winter, probably owing to age and blood pressure. Furthermore, more renal biopsies of severe cases were performed during spring and winter in patients with MCNS even after adjusting for the abovementioned host factors. This study suggests that seasonal factors influence the decision to perform renal biopsy as well as the pathogenesis of primary glomerular disease. Thus, our findings may provide important insights regarding the pathophysiology of primary glomerular disease.

Endothelial Autophagy in Coronary Microvascular Dysfunction and Cardiovascular Disease

Coronary microvascular dysfunction (CMD) refers to a subset of structural and/or functional disorders of coronary microcirculation that lead to impaired coronary blood flow and eventually myocardial ischemia. Amid the growing knowledge of the pathophysiological mechanisms and the development of advanced tools for assessment, CMD has emerged as a prevalent cause of a broad spectrum of cardiovascular diseases (CVDs), including obstructive and nonobstructive coronary artery disease, diabetic cardiomyopathy, and heart failure with preserved ejection fraction. Of note, the endothelium exerts vital functions in regulating coronary microvascular and cardiac function. Importantly, insufficient or uncontrolled activation of endothelial autophagy facilitates the pathogenesis of CMD in diverse CVDs. Here, we review the progress in understanding the pathophysiological mechanisms of autophagy in coronary endothelial cells and discuss their potential role in CMD and CVDs.

Analysis of Age, Sex, Lack of Response to Intravenous Immunoglobulin, and Development of Coronary Artery Abnormalities in Children With Kawasaki Disease in Japan

IMPORTANCE

Initial intravenous immunoglobulin (IVIG)-refractory status and prolonged fever are established risk factors for the development of coronary artery abnormalities (CAAs) among patients with acute-phase Kawasaki disease (KD). However, whether different risk factors exist for initial unresponsiveness to IVIG and CAA development remains unclear.

OBJECTIVE

To evaluate whether different risk factors exist for initial unresponsiveness to IVIG and CAA development among patients with KD (stratified by age at disease onset).

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included a consecutive sample of 2414 patients from a database of patients with KD from October 1, 1999, to September 30, 2019. The data were based on annual surveys (response rate, 100%) using hospital medical records across Wakayama Prefecture, Japan. Data were analyzed from March 6 to March 26, 2022.

EXPOSURES

The patient's age and diagnosis of KD by board-certified pediatricians using the criteria established by the Japan KD Research Committee.

MAIN OUTCOMES AND MEASURES

Initial unresponsiveness to IVIG, defined as treatment with optional or advanced therapies, and development of CAAs. Echocardiograms performed 1 month after KD onset using the Japanese Ministry of Health criteria evaluated the presence or absence of CAAs. Odds ratios (ORs) with 95% CIs of patient age at KD onset for unresponsiveness to IVIG and developing CAAs were calculated using multivariable logistic regression models.

RESULTS

A total of 2414 patients (1403 male patients [58.1%]; median age at onset of KD, 25 months [range, 1-212 months]) were included in the study: 550 younger than 12 months, 1342 aged 12 to 47 months, and 522 older than 47 months. A total of 535 patients (22.2%) received optional or advanced treatment and 68 patients (2.8%) developed CAAs 1 month after disease onset. The sex-adjusted OR among patients younger than 12 months for unresponsiveness to IVIG was 0.77 (95% CI, 0.59-0.99) and for development of CAAs was 1.94 (95% CI, 1.07-3.52); among those older than 47 months, the OR for unresponsiveness to IVIG was 1.32 (95% CI, 1.05-1.67) and for development of CAAs was 2.47 (95% CI, 1.39-4.39). After adjusting for IVIG administration, ORs among boys older than 47 months for unresponsiveness to IVIG was 1.14 (95% CI, 0.84-1.56) and for development of CAAs was 2.15 (95% CI, 1.08-4.30); among girls younger than 12 months, the OR for unresponsiveness to IVIG was 1.02 (95% CI, 0.65-1.60) and for development of CAAs was 3.79 (95% CI, 1.21-11.90).

CONCLUSIONS AND RELEVANCE

The results of this study suggest that risks of unresponsiveness to IVIG and the development of CAAs differ between infants with KD and older patients with KD. Residual risk factors for KD-related CAAs other than initial unresponsiveness to IVIG should be addressed, particularly in infants.

Spatiotemporal clusters of Kawasaki disease in South Korea from 2008 to 2017: A municipal-level ecological study

INTRODUCTION

As the etiology of Kawasaki disease (KD) remains unknown, identifying spatiotemporal clusters with proper stratification of KD could provide further evidence for investigating the triggers of KD. However, spatiotemporal distributions of KD with sex stratification have never been reported. Therefore, we aimed to analyze the spatiotemporal patterns of KD by sex in South Korea.

METHODS

We extracted epidemiologic week (Epiweek)-based KD cases in patients <5 years of age (ICD-10-CM code: M303) from 2008 to 2017 national health insurance service data at the 250 municipal level. To determine whether spatial autocorrelation and persistent municipal-level clusters exist, year- and sex-stratified global Moran's I statistics, Getis-Ord Gi* statistics, and emerging hotspot analysis on KD incidence were conducted.

RESULTS

A total of 72,510 KD cases were reported between 2008 and 2017 (male-to-female ratio = 1.40:1). Incidence has increased since 2008, with the highest incidence in 2016 (396.8 per 100,000 population). KD had seasonality of winter and summer but different by sex. Positive spatial autocorrelation was consistently reported in every stratum, with the 2011-2014 period having the strongest index value (total sex I = 0.286, p < 0.001; male I = 0.242, p < 0.001; female I = 0.213, p < 0.001). Hot spots were consistently detected in the northern parts, and cold spots were in the southern part for 9 years in both sexes. The emerging hot spot analysis showed new, consecutive, and sporadic hot spots on the northwestern and eastern coasts and new and sporadic cold spots in the southwestern part. However, the distribution and proportion of hot or cold spot types differed according to sex.

DISCUSSION

The spatiotemporal features of KD had limits to concluding that only infectious triggers result in KD occurrence. Therefore, our findings support the notion that KD is a syndrome with multiple factors, including infectious, genetic, and environmental factors, that are associated with sex differences.

Proteomic profiling of MIS-C patients indicates heterogeneity relating to interferon gamma dysregulation and vascular endothelial dysfunction

Multi-system Inflammatory Syndrome in Children (MIS-C) is a major complication of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in pediatric patients. Weeks after an often mild or asymptomatic initial infection with SARS-CoV-2 children may present with a severe shock-like picture and marked inflammation. Children with MIS-C present with varying degrees of cardiovascular and hyperinflammatory symptoms. Here we perform a comprehensive analysis of the plasma proteome of more than 1400 proteins in children with SARS-CoV-2. We hypothesize that the proteome would reflect heterogeneity in hyperinflammation and vascular injury, and further identify pathogenic mediators of disease. We show that protein signatures demonstrate overlap between MIS-C, and the inflammatory syndromes macrophage activation syndrome (MAS) and thrombotic microangiopathy (TMA). We demonstrate that PLA2G2A is an important marker of MIS-C that associates with TMA. We find that IFNγ responses are dysregulated in MIS-C patients, and that IFNγ levels delineate clinical heterogeneity.

Multi-inflammatory syndrome and Kawasaki disease in children during the COVID-19 pandemic: A nationwide register-based study and time series analysis

Aim

We investigated whether the ongoing COVID‐19 pandemic was associated with the occurrence of Kawasaki disease or with multi‐inflammatory syndrome in children (MIS‐C).

Methods

This national Finnish register‐based study was based on laboratory‐confirmed severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infections, MIS‐C and Kawasaki disease cases. We performed a time series analysis on the occurrence of Kawasaki disease in 2016–2020.

Results

In 2020, there were 5170 laboratory‐confirmed COVID‐19 cases in children under 18 years of age and five fulfilled the MIS‐C case definition. The occurrence of MIS‐C was 0.97 per 1000 (95% confidence interval: 0.31‐2.26) laboratory‐confirmed SARS‐CoV‐2 infections in children. Our time series analysis showed that Kawasaki disease cases decreased during the COVID‐19 pandemic. The seasonally adjusted incidence rate ratio was 0.49 (95% confidence interval: 0.32‐0.74) when it was compared to pre‐pandemic levels. This coincided with a reduced occurrence of respiratory infections, due to social distancing in the population.

Conclusion

This nationwide register‐based study found that MIS‐C was a rare complication of the SARS‐CoV‐2 infection. The occurrence of Kawasaki disease and respiratory infections decreased during the pandemic. This suggests that transmissible microbes may play an important role in Kawasaki disease and social distancing may have a protective effect.

Proteomic Profiling of MIS-C Patients Reveals Heterogeneity Relating to Interferon Gamma Dysregulation and Vascular Endothelial Dysfunction

Multi-system Inflammatory Syndrome in Children (MIS-C) is a major complication of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic in pediatric patients. Weeks after an often mild or asymptomatic initial infection with SARS-CoV-2 children may present with a severe shock-like picture and marked inflammation. Children with MIS-C present with varying degrees of cardiovascular and hyperinflammatory symptoms. We performed a comprehensive analysis of the plasma proteome of more than 1400 proteins in children with SARS-CoV-2. We hypothesized that the proteome would reflect heterogeneity in hyperinflammation and vascular injury, and further identify pathogenic mediators of disease. Protein signatures demonstrated overlap between MIS-C, and the inflammatory syndromes macrophage activation syndrome (MAS) and thrombotic microangiopathy (TMA). We demonstrate that PLA2G2A is a key marker of MIS-C that associates with TMA. We found that IFNγ responses are dysregulated in MIS-C patients, and that IFNγ levels delineate clinical heterogeneity.

Multisystem inflammatory syndrome in children and COVID-19 are distinct presentations of SARS-CoV-2

BACKGROUNDInitial reports from the severe acute respiratory coronavirus 2 (SARS-CoV-2) pandemic described children as being less susceptible to coronavirus disease 2019 (COVID-19) than adults. Subsequently, a severe and novel pediatric disorder termed multisystem inflammatory syndrome in children (MIS-C) emerged. We report on unique hematologic and immunologic parameters that distinguish between COVID-19 and MIS-C and provide insight into pathophysiology.METHODSWe prospectively enrolled hospitalized patients with evidence of SARS-CoV-2 infection and classified them as having MIS-C or COVID-19. Patients with COVID-19 were classified as having either minimal or severe disease. Cytokine profiles, viral cycle thresholds (Cts), blood smears, and soluble C5b-9 values were analyzed with clinical data.RESULTSTwenty patients were enrolled (9 severe COVID-19, 5 minimal COVID-19, and 6 MIS-C). Five cytokines (IFN-γ, IL-10, IL-6, IL-8, and TNF-α) contributed to the analysis. TNF-α and IL-10 discriminated between patients with MIS-C and severe COVID-19. The presence of burr cells on blood smears, as well as Cts, differentiated between patients with severe COVID-19 and those with MIS-C.CONCLUSIONPediatric patients with SARS-CoV-2 are at risk for critical illness with severe COVID-19 and MIS-C. Cytokine profiling and examination of peripheral blood smears may distinguish between patients with MIS-C and those with severe COVID-19.FUNDINGFinancial support for this project was provided by CHOP Frontiers Program Immune Dysregulation Team; National Institute of Allergy and Infectious Diseases; National Cancer Institute; the Leukemia and Lymphoma Society; Cookies for Kids Cancer; Alex's Lemonade Stand Foundation for Childhood Cancer; Children's Oncology Group; Stand UP 2 Cancer; Team Connor; the Kate Amato Foundations; Burroughs Wellcome Fund CAMS; the Clinical Immunology Society; the American Academy of Allergy, Asthma, and Immunology; and the Institute for Translational Medicine and Therapeutics.

Is multisystem inflammatory syndrome in children on the Kawasaki syndrome spectrum?

An alarming increase in children presenting with fever, hyperinflammation, and multiorgan dysfunction frequently requiring intensive care has been observed after severe acute respiratory syndrome coronavirus 2 infection. The illness resembles Kawasaki disease (KD), with coronary dilatation and aneurysm occurring in some. However, the cardiovascular manifestations were typically on the severe end of the KD spectrum, with cardiogenic shock a common presentation together with other features. This led to defining a unique syndrome named multisystem inflammatory syndrome in children (MIS-C). In this issue of the JCI, Lee and Day-Lewis et al. and Diorio et al. explored the clinical profiles associated with coronavirus disease 2019 in children. We posit that while splitting MIS-C into a separate disease may aid clinical management decisions, lumping it into the KD pot may better serve to understand pathobiology.

Circadian variation and seasonal distribution of implantable defibrillator detected new onset atrial fibrillation

BACKGROUND

We aimed to characterize the hourly, daily, and seasonally variations in the detection of new atrial fibrillation (AF) in heart failure patients implanted with a defibrillator.

METHODS

In 1309 patients enrolled in MADIT-RIT without AF at baseline, atrial arrhythmia data were analyzed from device interrogations. The circadian, weekly, and seasonal distribution of device detected AF was evaluated. The morning period was defined as 06:00-11:59, afternoon as 12:00-16:59, evening as 17:00-22:59, and the nighttime as 23:00-05:59.

RESULTS

During 17 months of follow-up, 66 (5%) patients developed new device-detected AF. AF patients were less likely to have ischemic cardiomyopathy and were more likely to have received an implantable cardioverter defibrillator rather than a cardiac resynchronization therapy with defibrillator. The highest number of AF occurred during the evening hours (25 patients [38%]) followed by a second peak in AF detection during the afternoon hours (21 patients [32%]). Importantly during the nighttime, new AF occurred only in three patients (4%). In comparison with the nighttime period, the odds ratio (OR) of developing AF during the evening time period was 8.5-fold higher (95% CI 7.3-9.7, P < .01). Detection of AF during the spring and winter seasons accounted for 67% of all new device-detected AF.

CONCLUSIONS

There is diurnal and seasonal variation in new onset AF. A double peak in the incidence of AF is observed during the afternoon and evening hours, and during the spring and winter seasons. This information may be useful when deciding when to screen at-risk patients for new AF.

Epidemiology of Kawasaki disease before and after universal Bacille Calmette-Guérin vaccination program was discontinued

AIM

Bacille Calmette-Guérin (BCG) vaccine (BCG) has been suggested to induce the primary immunity needed for the subsequent Kawasaki disease (KD). We studied the epidemiology of KD before and after the universal BCG vaccination ended in Finland in September 2006.

METHODS

Kawasaki disease cases were retrieved from national health registries from 1996 to 2016 for annual incidence rates. We then compared 612 433 children born in the BCG vaccination era, from 1 January 1996 to 30 August 2006, to 604 163 born after BCG era, from 1 September 2006 to 31 December 2016.

RESULTS

The annual incidence rates did not change after the BCG vaccination stopped. We found 370 first visits for KD by children born in the BCG era and 341 after universal BCG vaccination ended. The mean age at diagnosis increased from 2.6 years to 3.0 years (95% CI-0.64 to -0.012, P = .04) and the proportion of children with Kawasaki disease under 5 years decreased from 87% to 81% (95% CI 1%-12%, P = .02).

CONCLUSION

Discontinuing the universal BCG vaccination programme did not change the incidence rates of KD. The increased age at diagnosis could suggest that the pathogenesis of KD may be associated with the immunological pathways primed by BCG immunisation.

Seasonal Variation in Epidemiology of Kawasaki Disease-Related Coronary Artery Abnormalities in Japan, 1999-2017

BACKGROUND

Epidemiological studies show a U-shaped tendency in Kawasaki disease (KD)-related coronary artery abnormalities (CAAs) across age categories. Since studies suggest seasonal variations in KD onset, this study aimed to clarify the epidemiologic features of CAAs, considering the seasons of KD-occurrence.

METHODS

We analyzed 2,106 (males = 1,215, females = 891) consecutive KD cases from October 1999 through September 2017 using our electronic database of annual surveys, targeting all hospitals with pediatric departments across Wakayama, Japan. The primary outcome was the presence/absence of CAAs measured by echocardiography 1 month after KD onset. Odds ratios (ORs) and 95% confidence intervals (CIs) of combined patient age and sex for CAAs were calculated using logistic regression models adjusted for four seasons.

RESULTS

The median age was 25 (range, 1-212) months. The proportion of males decreased with increasing age. The youngest age group (<6 months) showed an inverse summer/autumn to winter/spring ratio (>1.0) in KD-occurrence. CAAs were observed in 2.8% of cases (males = 3.4%, females = 2.1%), which significantly lessened in summer than in other seasons. Moreover, 50% (n = 4/8) of cases with giant aneurysms experienced KD in autumn. Adjusted ORs for CAAs among males aged ≥60 months (3.0; 95%, CI 1.2-7.5) and females aged <6 months (3.6; 95%, CI 1.1-11.8) were significantly higher than those among males aged 12-35 months.

CONCLUSIONS

Cumulative 18-year data of consecutive KD cases from one area suggest the influence of interactions between patient age and sex on the development of KD-related CAAs. The season of KD-occurrence may reflect the diversity of agents.

Lower CMV and EBV Exposure in Children With Kawasaki Disease Suggests an Under-Challenged Immune System

Background: Kawasaki Disease (KD) is a pediatric vasculitis of which the pathogenesis is unclear. The hypothesis is that genetically pre-disposed children develop KD when they encounter a pathogen which remains most often unidentified or pathogen derived factors. Since age is a dominant factor, prior immune status in children could influence their reactivity and hence the acquisition of KD. We hypothesized that systemic immune responses early in life could protect against developing KD. With this study we tested whether the incidence of previous systemic cytomegalovirus (CMV) or Epstein-Barr virus (EBV) infection is lower in children with KD compared to healthy age-matched controls. Methods and Results: We compared 86 KD patients with an age-matched control group regarding CMV and EBV VCA IgG measurements (taken before or 9 months after IVIG treatment). We found that both CMV and EBV had an almost 2-fold lower seroprevalence in the KD population than in the control group. Conclusions: We suggest that an under-challenged immune system causes an altered immune reactivity which may affect the response to a pathological trigger causing KD in susceptible children.

An update on the epidemiology, length of stay, and cost of Kawasaki disease hospitalisation in the United States

BACKGROUND

Kawasaki disease is an acute vasculitis of childhood and is the leading cause of acquired heart disease in the developed countries.

METHODS

Data from hospital discharge records were obtained from the National Kids Inpatient Database for years 2009 and 2012. Hospitalisations by months, hospital regions, timing of admission, insurance types, and ethnicity were analysed. Length of stay and total charges were also analysed.

RESULTS

There were 10,486 cases of Kawasaki disease from 12,678,005 children hospitalisation. Kawasaki disease was more common between 0 and 5 years old, in male, and in Asian. The January-March quarter had the highest rate compared to the lowest in the July-September quarter (OR=1.62, p &lt; 0.001). Admissions on the weekend had longer length of stay [4.1 days (95 % CI: 3.97-4.31)] as compared to admissions on a weekday [3.72 days (95 % CI: 3.64-3.80), p &lt; 0.001]. Blacks had the longest length of stay and whites had the shortest [4.33 days (95 % CI: 4.12-4.54 days) versus 3.60 days (95 % CI: 3.48-3.72 days), p &lt; 0.001]. Coronary artery aneurysm was identified in 2.7 % of all patients with Kawasaki disease. Children with coronary artery aneurysm were hospitalised longer and had higher hospital charge. Age, admission during weekend, and the presence of coronary artery aneurysm had significant effect on the length of stay.

CONCLUSIONS

This report provides the most updated epidemiological information on Kawasaki disease hospitalisation. Age, admissions during weekend, and the presence of coronary artery aneurysm are significant contributors to the length of stay.

Significance of Differential Characteristics in Infantile Kawasaki Disease

BACKGROUND AND OBJECTIVES

Immunological variability in Kawasaki disease (KD) shows age-specific differences; however, specific differences in laboratory values have not been compared between infants and non-infants with KD. We compared age-adjusted Z-values (Z) of white and red blood cells in infants with KD with those in non-infants with KD.

METHODS

This study retrospectively investigated 192 infants and 667 non-infants recruited between 2003 and 2015 at the Korea University Hospital. Laboratory values for infants with KD and non-infants with KD were analyzed and age-unadjusted raw values (R) and age-adjusted Z for blood cells counts were determined.

RESULTS

Z in infants with KD during pre-intravenous immunoglobulin (IVIG), post-IVIG, and chronic phases showed increased lymphopenia and eosinophilia, low neutrophil:lymphocyte and neutrophil:eosinophil ratios, worse anemia, increased thrombocytosis, and reduced erythrocyte sedimentation rates compared with those in non-infants with KD. The optimal cut-off value for pre-IVIG Z-hemoglobin for prediction of KD in all patients was <-0.01 (area under the curve [AUC], 0.914; sensitivity/specificity, 0.999/0.886; p=0.04). The optimal cut-off value for pre-IVIG C-reactive protein (CRP) for prediction of KD in infants compared to that in febrile control infants was >40 mg/L (AUC, 0.811; sensitivity/specificity, 0.712/0.700; p=0.04).

CONCLUSIONS

Laboratory characteristics enable differentiation between infants and non-infants with KD and contribute to a better understanding of changes in blood cell counts. Infants with incomplete KD can be more easily differentiated from infants with simple febrile illness using pre-IVIG Z-hemoglobin and pre-IVIG CRP values.

Clustering and climate associations of Kawasaki Disease in San Diego County suggest environmental triggers

Kawasaki Disease (KD) is the most common cause of pediatric acquired heart disease, but its etiology remains unknown. We examined 1164 cases of KD treated at a regional children's hospital in San Diego over a period of 15 years and uncovered novel structure to disease incidence. KD cases showed a well-defined seasonal variability, but also clustered temporally at much shorter time scales (days to weeks), and spatiotemporally on time scales of up to 10 days and spatial scales of 10-100 km. Temporal clusters of KD cases were associated with strongly significant regional-scale air temperature anomalies and consistent larger-scale atmospheric circulation patterns. Gene expression analysis further revealed a natural partitioning of KD patients into distinct groups based on their gene expression pattern, and that the different groups were associated with certain clinical characteristics that also exhibit temporal autocorrelation. Our data suggest that one or more environmental triggers exist, and that episodic exposures are modulated at least in part by regional weather conditions. We propose that characterization of the environmental factors that trigger KD in genetically susceptible children should focus on aerosols inhaled by patients who share common disease characteristics.