A nationwide incidence survey of Kawasaki disease in 1985-1986 in Japan

The etiologies of Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis that affects young children and can result in coronary artery aneurysms. The etiology is currently unknown, but new clues from the epidemiology of KD in Japan, the country of highest incidence, are beginning to shed light on what may trigger this acute inflammatory condition. Additional clues from the global changes in KD incidence during the COVID-19 pandemic, coupled with a new birth cohort study from Japan, point to the potential role of person-to-person transmission of an infectious agent. However, the rising incidence of KD in Japan, with coherent waves across the entire country, points to an increasing intensity of exposure that cannot be explained by person-to-person spread. This Review discusses new and historical observations that guide us toward a better understanding of KD etiology and explores hypotheses and interpretations that can provide direction for future investigations. Once the etiology of KD is determined, accurate diagnostic tests will become available, and new, less expensive, and more effective targeted therapies will likely be possible. Clearly, solving the mystery of the etiologies of KD remains a priority for pediatric research.

Age-Dependent Variations in Kawasaki Disease Incidence in Japan

Importance

The etiology of Kawasaki disease (KD) remains elusive, with immunologic and epidemiologic data suggesting different triggers in individuals who are genetically susceptible. KD remains the most common cause of acquired heart disease in pediatric patients, and Japan is the country of highest incidence, with an increasing number of cases.

Objective

To investigate whether an analysis of the epidemiologic KD record in Japan stratified by age and prefecture (subregion) may yield new clues regarding mechanisms of exposure to etiologic agents associated with KD.

Design, Setting, and Participants

This cross-sectional study was conducted using a dataset of patients with KD with detailed information on location and age at onset created through nationwide surveys of hospitals caring for pediatric patients with KD throughout Japan. Pediatric patients hospitalized in Japan for KD from 1970 to 2020 were included. Data were analyzed from January 2022 to January 2024.

Exposure

Pediatric patients with KD.

Main Outcomes and Measures

The KD dataset was analyzed by patient age (infants [aged <6 months], toddlers [aged 6 to <24 months], children aged 2 years [aged 24 to <36 months], and children and adolescents aged 3 years or older [aged ≥36 months]), with investigations of seasonal cycles, interannual variations, and correlations across regions.

Results

Among 422 528 pediatric patients (243 803 males [57.7%] and 178 732 females [42.3%]; median [IQR] age, 23.69 [11.96-42.65] months), infants, toddlers, and patients aged 3 years or older exhibited different rates of increase in KD incidence, seasonality, and degrees of coherence of seasonality across prefectures. Although the mean (SD) incidence of KD among infants remained relatively stable over the past 30 years compared with older patients (1.00 [0.07] in 1987-1992 to 2.05 [0.11] in 2011-2016), the mean (SD) incidence rate for children and adolescents aged 3 years or older increased 5.2-fold, from 1.00 (0.08) in 1987 to 1992 to 5.17 (0.46) in 2014 to 2019. Patients aged 3 years or older saw a reduction in mean (SD) incidence, from peaks of 5.71 (0.01) in October 2014 through June 2015 and July 2018 through March 2019 to 4.69 (0.11) in 2016 to 2017 (17.8% reduction) not seen in younger children. The seasonal cycle varied by age group; for example, mean (SD) incidence peaked in July and August (5.63 [0.07] cases/100 000 individuals) for infants and in December and January (4.67 [0.13] cases/100 000 individuals) for toddlers. Mean (SD) incidence changed dramatically for toddlers beginning in the early 2010s; for example, the normalized mean (SD) incidence among toddlers for October was 0.74 (0.03) in 1992 to 1995 and 1.10 (0.01) in 2016 to 2019. Across Japan, the seasonal cycle of KD incidence of older children and adolescents exhibited mean (SD) correlation coefficients between prefectures as high as 0.78 (0.14) for prefecture 14 among patients aged 3 years or older, while that of infants was much less (highest mean [SD] correlation coefficient, 0.43 [0.23]).

Conclusions and Relevance

This study found distinct temporal signatures and changing spatial consistency of KD incidence across age groups, suggesting different age-related mechanisms of exposure. Some results suggested that social factors may modulate exposure to etiologic agents of KD; however, the increase in KD incidence in older children coupled with the correlation across prefectures of KD incidence suggest that the intensity of an environmental exposure that triggers KD in this age group may have increased over time.

Analysis of Plasmablasts From Children With Kawasaki Disease Reveals Evidence of a Convergent Antibody Response to a Specific Protein Epitope

BACKGROUND

Kawasaki disease (KD) is a febrile illness of young childhood that can result in coronary artery aneurysms and death. Coronavirus disease 2019 (COVID-19) mitigation strategies resulted in a marked decrease in KD cases worldwide, supporting a transmissible respiratory agent as the cause. We previously reported a peptide epitope recognized by monoclonal antibodies (MAbs) derived from clonally expanded peripheral blood plasmablasts from 3 of 11 KD children, suggesting a common disease trigger in a subset of patients with KD.

METHODS

We performed amino acid substitution scans to develop modified peptides with improved recognition by KD MAbs. We prepared additional MAbs from KD peripheral blood plasmablasts and assessed MAb characteristics that were associated with binding to the modified peptides.

RESULTS

We report a modified peptide epitope that is recognized by 20 MAbs from 11 of 12 KD patients. These MAbs predominantly use heavy chain VH3-74; two-thirds of VH3-74 plasmablasts from these patients recognize the epitope. The MAbs were nonidentical between patients but share a common complementarity-determining region 3 (CDR3) motif.

CONCLUSIONS

These results demonstrate a convergent VH3-74 plasmablast response to a specific protein antigen in children with KD, supporting one predominant causative agent in the etiopathogenesis of the illness.

Kawasaki disease in children: a retrospective cross-sectional study

Introduction

Kawasaki disease (KD) is a systemic vasculitis, seen mostly in children. Epidemiology of KD is dependent on geographical location and seasonality. Although many years have passed since the first report of KD, multiple related factors are still unknown.

Material and methods

We investigated the clinical, paraclinical, and therapeutic aspects of KD in Kerman, Iran by performing a retrospective, descriptive, cross-sectional study on all children hospitalized due to KD between 2007 and 2020.

Results

A total of 340 patients with mean ±SD age of 29.83 ±22.55 months participated in the study. Most of our patients were two to five years old. The male : female ratio was ~ 1.4 : 1. A few of our patients had a family history of KD or vasculitis (0.3%, 1.7%). Typical KD was more common by a large margin (316 patients with typical KD). More than half of our patients had a duration of hospitalization of under ten days. All of our patients were febrile. Hand/foot and lip/mouth changes were the second and third most common clinical findings in more than 60% of our patients. Other manifestations were conjunctivitis in 40%, skin rashes in 34.8%, gastrointestinal manifestations in 33.9%, and lymphadenopathy in 25.3%. Echocardiography revealed abnormalities in 78.6% of the participants; coronary artery aneurysm (CAA) was the most frequent (22.5%) and follow-up echocardiography revealed that all of them regressed within 6 months after treatment. The two laboratory tests with the highest ratio of abnormality were erythrocyte sedimentation rate (95%) and hemoglobin (83.3%). C-reactive protein and liver function tests were also abnormal in most patients. All of our patients received intravenous immunoglobulin and acetylsalicylic acid.

Conclusions

Kawasaki disease must be considered in every febrile child, especially those with risk factors, because timely diagnosis and treatment are essential to prevent complications. Health policies should focus on appropriate diagnosis and treatment to prevent the occurrence of sequelae.

Clinical characteristics of patients with recurrent Kawasaki disease: a nationwide cohort study of 19 456 patients with minimum 3-year follow up

OBJECTIVE

To identify the clinical characteristics of patients with recurrent Kawasaki disease (KD).

DESIGN

A nationwide, population-based, cohort study using the Korean National Health Insurance claims database between 2013 and 2016.

PATIENTS

A total of 19 456 patients under the age of 5 years who were diagnosed with initial episode of KD were included. A minimum follow-up period of 3 years was mandatory for inclusion.

MAIN OUTCOME MEASURES

The epidemiological and clinical profiles were compared between KD patients with and without recurrence.

RESULTS

The overall recurrence rate of KD was 3.84% (n=748), and the median interval to recurrence was 498 days (IQR: 257-860 days). Approximately 70% of all recurrences occurred within 2 years of the initial diagnosis. The annual proportions of recurrence were 40%, 28%, 18%, 8% and 4% from the first to the fifth year following the initial episode, respectively. Recurrence rates were significantly higher in patients aged <1 year than in those aged 4-5 years (4.65% vs 2.22%) and those who showed resistance to an initial dose of intravenous immunoglobulin (IVIG) (10.00% vs 3.18%). Allergic comorbidities and coronary artery complications at the initial episode were not associated with increased rates of recurrence.

CONCLUSIONS

We clearly identified the annual recurrence rates and their intervals from the initial episode according to the various factors identified, including young age and resistance to initial IVIG. Our results, based on a nationwide cohort, can be used as reference for follow-up management in patients with KD and in future studies.

Clinical Course and Outcomes in Patients with Left Ventricular Dysfunction Due to Myocardial Infarction After Kawasaki Disease

Long-term outcomes of patients with left ventricular dysfunction after Kawasaki disease (KD) remain unknown. The clinical course of 37 patients (29 males 8 females) with left ventricular ejection function (LVEF) less than 45% after KD since 1978 was retrospectively investigated. Cardiac events in this study were defined as admissions because of heart failure, fatal ventricular arrhythmias, heart transplantation, and death. Their ages when evaluated ranged from 1 to 70 years (median 35 years). The onset of KD ranged from 2 months to 20 years (median 21 months). All patients had bilateral coronary artery lesions, and multi-vessel occlusion occurred in 31 patients (84%). Previous myocardial infarction (MI) was found in 28 patients (76%). The interval from the onset of acute KD to the initial MI ranged from 15 days to 25 years (median 3 months). Reperfusion therapy was successful in 6 patients (30%), and coronary artery bypass grafting was performed in 23 patients (62%). Non-sustained ventricular tachycardia and fatal ventricular arrhythmias were detected in 11 patients and 22 patients, respectively. There were 15 deaths (41%). The 20-year and 50-year survival rates after KD were 84% (95% CI 67-92) and 54% (34-73), respectively (n = 37). The 30-year cardiac event-free rate after the detection of low LVEF was 42% (95% CI 27-59). The cutoff point of the left ventricular end-diastolic dimension for cardiac events was 65 mm. Patients with low LVEF had fatal ventricular arrhythmias and a worsening of their ischemic cardiomyopathy after 30 years of age and their outcomes were poor.

Kawasaki Disease and Vaccination: Prospective Case-Control and Case-Crossover Studies among Infants in Japan

The causal effects of vaccines on Kawasaki disease (KD) remain elusive. We aimed to examine the association between vaccines administered during infancy and the development of KD in Japan. We conducted a multicenter prospective case-control study using questionnaires and compared the vaccination status of infants (age: 6 weeks to 9 months) who developed KD (KD group; n = 102) and those who did not develop KD (non-KD group; n = 139). Next, we performed a case-crossover study of 98 cases in the KD group and compared the status of vaccinations between the case and control periods. We also compared the incidence of KD in children for each 5-year period before and after the addition of new vaccines (2012–2013) using data from the Nationwide Survey of KD. In the case-control study, the vaccination status of the KD and control groups did not differ to a statistically significant extent. Multivariable analysis of the vaccination status and patient backgrounds showed no significant association between vaccination and KD development. In the case-crossover study, the status of vaccinations during the case and control periods did not differ to a statistically significant extent. In the analysis of data from the Nationwide Survey of KD, the incidence of KD in children of ages subject to frequent vaccination showed no significant increases in the latter five years, 2014–2018. Based on these prospective analyses, we confirmed that vaccination in early infancy did not affect the risk of KD.

Clinical Characteristics of Patients With Kawasaki Disease Whose Siblings Had the Same Disease

BACKGROUND

Some patients with Kawasaki disease (KD) have siblings who developed the same disease. Using a large-scale epidemiologic dataset, the present study aimed to determine the clinical characteristics of this population.

METHODS

We analyzed 89,725 patients diagnosed with KD during 2011-2018 who were registered in the nationwide Japanese KD survey database. Multivariable logistic regression analyses were performed to determine factors associated with sibling history of KD.

RESULTS

Of the 89,725 patients, 1777 (2%) had sibling history of KD. Annual prevalence ranged from 1.5% to 2.3% during the study period and showed a tendency toward an increasing trend. Patients with recurrent KD and parental history of KD were significantly associated with sibling history of KD (adjusted odds ratio [95% confidence interval] = 2.15 [1.82-2.54] and 2.64 [2.02-3.47], respectively). Although patients with a sibling history of KD were significantly associated with initial intravenous immunoglobulin treatment resistance (1.14 [1.02-1.28]), no significant association was found between sibling history and coronary artery abnormality development. Among patients with a sibling history of KD, male patients were less likely to have recurrent KD than female patients (0.68 [0.49-0.96]).

CONCLUSIONS

The significant association between sibling history and parental history may indicate genetic susceptibility to KD onset. Among those with a sibling history, recurrent KD was more likely to occur in female patients. Further studies focusing on this population may contribute toward identification of the cause of KD onset.

Comprehensive pathogen detection in sera of Kawasaki disease patients by high-throughput sequencing: a retrospective exploratory study

Background

Kawasaki disease (KD) is an idiopathic systemic vasculitis that predominantly damages coronary arteries in children. Various pathogens have been investigated as triggers for KD, but no definitive causative pathogen has been determined. As KD is diagnosed by symptoms, several days are needed for diagnosis. Therefore, at the time of diagnosis of KD, the pathogen of the trigger may already be diminished. The aim of this study was to explore comprehensive pathogens in the sera at the acute stage of KD using high-throughput sequencing (HTS).

Methods

Sera of 12 patients at an extremely early stage of KD and 12 controls were investigated. DNA and RNA sequences were read separately using HTS. Sequence data were imported into the home-brew meta-genomic analysis pipeline, PATHDET, to identify the pathogen sequences.

Results

No RNA virus reads were detected in any KD case except for that of equine infectious anemia, which is known as a contaminant of commercial reverse transcriptase. Concerning DNA viruses, human herpesvirus 6B (HHV-6B, two cases) and Anelloviridae (eight cases) were detected among KD cases as well as controls. Multiple bacterial reads were obtained from KD and controls. Bacteria of the genera Acinetobacter, Pseudomonas, Delfita, Roseomonas, and Rhodocyclaceae appeared to be more common in KD sera than in the controls.

Conclusion

No single pathogen was identified in serum samples of patients at the acute phase of KD. With multiple bacteria detected in the serum samples, it is difficult to exclude the possibility of contamination; however, it is possible that these bacteria might stimulate the immune system and induce KD.

Kawasaki disease in siblings in close temporal proximity to each other-what are the implications?

Kawasaki disease (KD) is the commonest medium vessel vasculitis in children. The etiology of KD remains an enigma despite extensive research. Infections are considered to be one of the triggers for KD, especially in genetically susceptible hosts. KD occurring within a short time interval among siblings is an important clinical observation supporting this hypothesis. In addition, siblings of children with KD are at a higher risk of developing the disease as compared with other children. Screening for KD in febrile siblings, therefore, seems prudent. This would help initiate timely therapy and prevent complications. We briefly review 16 English language reports of KD in siblings diagnosed within 1 month of each other to highlight its etiological and therapeutic implications.

Key Points • KD should be suspected in febrile children who have a sibling recently diagnosed with KD. • Etiological studies should also focus on siblings who develop KD in close temporal proximity.

A Protein Epitope Targeted by the Antibody Response to Kawasaki Disease

BACKGROUND

Kawasaki disease (KD) is the leading cause of childhood acquired heart disease in developed nations and can result in coronary artery aneurysms and death. Clinical and epidemiologic features implicate an infectious cause but specific antigenic targets of the disease are unknown. Peripheral blood plasmablasts are normally highly clonally diverse but the antibodies they encode are approximately 70% antigen-specific 1-2 weeks after infection.

METHODS

We isolated single peripheral blood plasmablasts from children with KD 1-3 weeks after onset and prepared 60 monoclonal antibodies (mAbs). We used the mAbs to identify their target antigens and assessed serologic response among KD patients and controls to specific antigen.

RESULTS

Thirty-two mAbs from 9 of 11 patients recognize antigen within intracytoplasmic inclusion bodies in ciliated bronchial epithelial cells of fatal cases. Five of these mAbs, from 3 patients with coronary aneurysms, recognize a specific peptide, which blocks binding to inclusion bodies. Sera from 5/8 KD patients day ≥ 8 after illness onset, compared with 0/17 infant controls (P < .01), recognized the KD peptide antigen.

CONCLUSIONS

These results identify a protein epitope targeted by the antibody response to KD and provide a means to elucidate the pathogenesis of this important worldwide pediatric problem.

A Comprehensive Update on Kawasaki Disease Vasculitis and Myocarditis

PURPOSE OF THE REVIEW

Kawasaki disease (KD) is a childhood systemic vasculitis of unknown etiology that causes coronary artery aneurysms (CAA), and if left undiagnosed can result in long-term cardiovascular complications and adult cardiac disease. Up to 20% of KD children fail to respond to IVIG, the mainstay of therapy, highlighting the need for novel therapeutic strategies. Here we review the latest findings in the field regarding specific etiology, genetic associations, and advancements in treatment strategies to prevent coronary aneurysms.

RECENT FINDINGS

Recent discoveries using the Lactobacillus casei cell wall extract (LCWE)-induced KD vasculitis mouse model have accelerated the study of KD pathophysiology and have advanced treatment strategies including clinical trials for IL-1R antagonist, Anakinra. KD remains an elusive pediatric vasculitis syndrome and is the leading cause of acquired heart disease among children in the USA and developed countries. Advancements in combination treatment for refractory KD with further understanding of novel genetic risk factors serve as a solid foundation for future research endeavors in the field.

Assessment of the Clinical Heterogeneity of Kawasaki Disease Using Genetic Variants of BLK and FCGR2A

BACKGROUND AND OBJECTIVES

Patients with Kawasaki disease (KD) are clinically heterogeneous because its diagnosis is based solely on clinical observation and there are no definitive biomarkers. We dissected the clinical heterogeneity of KD patients using the KD-associated genetic variants.

METHODS

We performed a genetic association analysis in several KD subgroups categorized by clinical characteristics using the KD-associated variants of the B lymphoid tyrosine kinase (BLK; rs6993775) and Fc gamma receptor II a (FCGR2A; rs1801274) in a large number of case (n=1,011) and control (n=4,533) samples.

RESULTS

BLK and FCGR2A were very significantly associated with KD in Korean KD patients (odds ratio [OR],1.48; p=4.63×10⁻¹¹ for BLK, and OR, 1.26; p=1.42×10⁻⁴ for FCGR2A). However, in KD subgroup analysis, we found that neither BLK nor FCGR2A were associated with either incomplete Kawasaki disease (iKD) type patients or those older than 5 years of age (p>0.2), suggesting that patients with iKD or those older than 5 years of age are a unique subgroup of KD. In genetic association analysis after excluding iKD patients and those older than 5 years old, we found that BLK was associated with all KD subgroups, whereas FCGR2A was specifically associated with male KD patients younger than 1 year of age (OR, 2.22; p=2.35×10⁻⁵).

CONCLUSIONS

KD is a clinically and genetically heterogeneous disease. These findings will provide new insights into the clinical and genetic heterogeneity of KD.

Melatonin: A hypothesis for Kawasaki disease treatment

Kawasaki disease (KD) is the most common cause of acquired heart disease with unknown etiology among children in developed countries. Acute inflammation of the vasculature, genetic susceptibility and immunopathogenesis based on a transmittable and infectious origin, are the pathologic events involved in the early inflammatory etiology and progression of this disease. However, the exact causes of KD remain unknown. Current proposed recommendations include three therapy lines; firstly, an initial standard therapy with intravenous immunoglobulin (IVIG) followed by aspirin. Secondly, in cases of high risk of coronary lesions, the adjunctive therapy with corticosteroid is commonly considered. Thirdly, in KD patients refractory to the previous therapies, tumor necrosis factor (TNF-α) antagonists are being used to modulate pro-inflammatory cytokines. In view of this status quo, our starting hypothesis is that the ubiquitous and non-toxic neurohormone melatonin could be of critical importance in developing novel adjuvant therapies against KD, as it occurs with a plethora of other diseases. Considering its pleiotropic properties, particularly its antiinflammatory and immunoregulatory capacities, melatonin should be of great therapeutic interest for helping to control the main pathologic features of KD patients. In addition, this multifunctional indole has a safe pharmacological profile, enhancing the therapeutic activity of several drugs and reducing their possible side effects. Consequently, melatonińs actions to manage KD need to be tested in further clinical studies.

The Epidemiology and Pathogenesis of Kawasaki Disease

Epidemiologic and clinical features of Kawasaki Disease (KD) strongly support an infectious etiology. KD is worldwide, most prominently in Japan, Korea, and Taiwan, reflecting increased genetic susceptibility among Asian populations. In Hawaii, KD rates are 20-fold higher in Japanese ethnics than in Caucasians, intermediate in other ethnicities. The age distribution of KD, highest in children < 2 yo, lower in those < 6 months, is compatible with infection by a ubiquitous agent resulting in increasing immunity with age and with transplacental immunity, as with some classic viruses. The primarily winter-spring KD seasonality and well-documented Japanese epidemics with wave-like spread also support an infectious trigger. We hypothesize KD pathogenesis involves an RNA virus that usually causes asymptomatic infection but KD in a subset of genetically predisposed children. CD8 T cells, oligoclonal IgA, and upregulation of cytotoxic T cell and interferon pathway genes in the coronaries in fatal KD also support a viral etiology. Cytoplasmic inclusion bodies in ciliated bronchial epithelium identified by monoclonal antibodies made from oligoclonal IgA heavy chains also supports a viral etiology. Recent availability of "second generation" antibodies from KD peripheral blood plasmablasts may identify a specific viral antigen. Thus, we propose an unidentified ("new") RNA virus infects bronchial epithelium usually causing asymptomatic infection but KD in a subset of genetically predisposed children. The agent persists in inclusion bodies, with intermittent respiratory shedding, entering the bloodstream via macrophages targeting coronaries. Antigen-specific IgA plasma cells and CD8 T cells respond but coronaries can be damaged. IVIG may include antibody against the agent. Post infection, 97-99% of KD patients are immune to the agent, protected against recurrence. The agent can spread either from those with asymptomatic primary infection in winter-spring or from a previously infected contact who intermittently sheds the agent.

Nationwide surveys show that the incidence of recurrent Kawasaki disease in Japan has hardly changed over the last 30 years

AIM

Since Kawasaki disease (KD) was first reported in 1967, its aetiology has been intensively investigated, but remains unclear. We investigated the incidence of recurrent KD in Japan in 2003-2012, compared with previous data from our team, and assessed the potential risk factors for disease recurrence.

METHODS

Data from nationwide KD surveys were retrospectively analysed and 81 310 patients were observed. Incidence rates were compared between different years.

RESULTS

The incidence rates for recurrent KD were 3.89 per 1000 person-years (January 2003 to December 2012), 4.95 (July 2003 to December 2010), 6.48 (January 2003 to December 2006) and 6.51 (January 2007 to December 2010). These rates were almost consistent with our previous data, which started in the 1980s. The incidence rate for recurrence was statistically higher among males, patients under the age of three years and those who received intravenous immunoglobulin or steroid therapy at the initial episode. The presence of cardiac sequelae during the initial episode did not affect the recurrence incidence.

CONCLUSION

Although the incidence of KD has increased, the incidence of recurrent KD has remained largely unchanged over the past 30 years. Risk factors for recurrence included male sex, young age and initial resistance to immunoglobulin therapy.

Pediatric Kawasaki Disease and Adult Human Immunodeficiency Virus Kawasaki-Like Syndrome Are Likely the Same Malady

Background.  Pediatric Kawasaki disease (KD) and human immunodeficiency virus (HIV)⁺ adult Kawasaki-like syndrome (KLS) are dramatic vasculitides with similar physical findings. Both syndromes include unusual arterial histopathology with immunoglobulin (Ig)A⁺ plasma cells, and both impressively respond to pooled Ig therapy. Their distinctive presentations, histopathology, and therapeutic response suggest a common etiology. Because blood is in immediate contact with inflamed arteries, we investigated whether KD and KLS share an inflammatory signature in serum. Methods.  A custom multiplex enzyme-linked immunosorbent assay (ELISA) defined the serum cytokine milieu in 2 adults with KLS during acute and convalescent phases, with asymptomatic HIV⁺ subjects not taking antiretroviral therapy serving as controls. We then prospectively collected serum and plasma samples from children hospitalized with KD, unrelated febrile illnesses, and noninfectious conditions, analyzing them with a custom multiplex ELISA based on the KLS data. Results.  Patients with KLS and KD subjects shared an inflammatory signature including acute-phase reactants reflecting tumor necrosis factor (TNF)-α biologic activity (soluble TNF receptor I/II) and endothelial/smooth muscle chemokines Ccl1 (Th2), Ccl2 (vascular inflammation), and Cxcl11 (plasma cell recruitment). Ccl1 was specifically elevated in KD versus febrile controls, suggesting a unique relationship between Ccl1 and KD/KLS pathogenesis. Conclusions.  This study defines a KD/KLS inflammatory signature mirroring a dysfunctional response likely to a common etiologic agent. The KD/KLS inflammatory signature based on elevated acute-phase reactants and specific endothelial/smooth muscle chemokines was able to identify KD subjects versus febrile controls, and it may serve as a practicable diagnostic test for KD.

Recent Advances in Kawasaki Disease

Kawasaki disease (KD) is characterized with acute systemic vasculitis, occurs predominantly in children between 6 months to 5 years of age. Patients with this disease recover well and the disease is self-limited in most cases. Since it can lead to devastating cardiovascular complications, KD needs special attention. Recent reports show steady increases in the prevalence of KD in both Japan and Korea. However, specific pathogens have yet to be found. Recent advances in research on KD include searches for genetic susceptibility related to KD and research on immunopathogenesis based on innate and acquired immunity. Also, search for etiopathogenesis and treatment of KD has been actively sought after using animal models. In this paper, the recent progress of research on KD was discussed.

The Complexities of the Diagnosis and Management of Kawasaki Disease

Kawasaki disease (KD) must be considered in the differential diagnosis of any child with fever for 4 to 5 days and compatible clinical and laboratory features, and in any infant with prolonged fever and compatible laboratory features, even in the absence of the classic clinical signs. Prompt therapy is required, because delayed or unrecognized KD can lead to lifelong heart disease or death in previously healthy children. Most children with KD respond to a single 2 g/kg dose of intravenous gammaglobulin with oral aspirin, but a small subset require additional therapies to resolve the clinical illness.

Kawasaki disease: insights into pathogenesis and approaches to treatment

This Review summarizes recent advances in understanding of the pathologic processes and pathophysiologic mechanisms leading to coronary arteritis in Kawasaki disease, and describes current approaches to its treatment. Kawasaki disease is the most common cause of acquired heart disease among children in developed countries, in whom the resulting coronary artery abnormalities can cause myocardial ischaemia, infarction and even death. Epidemiologic data strongly suggest an infectious aetiology, although the causative agent has yet to be identified. Genetic factors also increase susceptibility to Kawasaki disease, as indicated by its strikingly high incidence rate in children of Asian ethnicity and by an increased incidence in first-degree family members. The treatment of Kawasaki disease is based on timely administration of intravenous immunoglobulin and aspirin. However, the management of patients who do not respond to this standard therapy remains challenging; although several options are available, comparative data on which to base treatment decisions are scarce. The added value of adjunctive therapy with corticosteroids in patients at particularly high risk of coronary complications has been demonstrated in Japanese populations, but identification of high-risk patients has proven to be difficult in ethnically diverse populations.

Clinical features of recurrent Kawasaki disease and its risk factors

The clinical features and risk factors for recurrence of Kawasaki disease (KD) remain unclear. In order to summarize clinical features of recurrent KD and identify risk factors associated with recurrence, we conducted a retrospective review of the medical records of consecutive cases of KD from January 2002 to December 2010. Demographic, clinical, laboratory, and echocardiographic data were analyzed. The maximum coronary artery Z score normalized against body surface area was assessed using coronary artery diameters. At the first onset of recurrent KD, children had longer durations of fever before intravenous immunoglobulin (IVIG) treatment and higher levels of alanine aminotransferase, serum aspartate aminotransferase (AST), and lower hemoglobin levels than those with a single episode of KD. Multivariate logistic regression analysis showed that long durations of fever before IVIG treatment, high AST levels, and reduced hemoglobin levels were significantly associated with recurrent KD. Ten of the 22 recurrent KD children had coronary artery complications during the first onset episode, and six (60 %) of these also had coronary artery complications during the recurrence. Children with longer durations of fever, lower hemoglobin levels, and higher AST levels may be at increased risk for KD and coronary artery complications are more likely to occur in children with recurrent KD if they were present during the first episode.

Can a systems biology approach unlock the mysteries of Kawasaki disease?

Kawasaki disease (KD) is a systemic inflammatory illness of childhood that particularly affects the coronary arteries. It can lead to coronary artery aneurysms, myocardial infarction, and sudden death. Clinical and epidemiologic data support an infectious cause, and the etiology remains unknown, but recent data support infection with a 'new' virus. Genetic factors influence KD susceptibility; the incidence is 10-fold higher in children of Asian when compared with Caucasian ethnicity. Recent research has identified genes affecting immune response that are associated with KD susceptibility and outcome. A re-examination of the pathologic features of KD has yielded a three process model of KD vasculopathy, providing a framework for understanding the KD arterial immune response and the damage it inflicts and for identifying new therapeutic targets for KD patients with coronary artery abnormalities. The researcher is faced with many challenges in determining the pathogenesis of KD. A systems biology approach incorporating genomics, proteomics, transcriptomics, and microbial bioinformatics analysis of high-throughput sequence data from KD tissues could provide the keys to unlocking the mysteries of this potentially fatal illness of childhood.

Genetic susceptibility to Kawasaki disease: analysis of pattern recognition receptor genes

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology occurring in infants and children. Several lines of evidence suggested the importance of genetic factors and infectious triggers for the pathogenesis of KD. We have reported that oral administration of a pure NOD1 ligand induces coronary arteritis in mice without fail. Since NOD1 is one of the pattern recognition receptors (PRRs) which play important roles in the innate immunity for the detection of microbial substances and induce inflammatory responses, we have investigated the association of PRR genes with the development of KD. Forty-six tagging-SNPs in 19 PRR genes were genotyped in Japanese KD patients (n=356, consisting of two groups) and controls (n=215). The genotypes and allele frequencies of each SNP or haplotype were compared between KD patients and controls. As a result, we did not find any genes with strongly contributed to the development of KD. A haplotype, G-T-C-C, in the NOD1 gene, was associated with lower risk for KD development (KD 1st group versus controls: 23.2% versus 35.3%, Pc=0.0385). The second-round case-control study in KD group 2 demonstrated that a haplotype, T-T-C-G-A-C, in the NLRP1 gene was associated with a higher risk for KD development (4.9% versus 1.2%, Pc=0.035). From the association analysis of SNPs and haplotypes of 19 PRR genes, NOD1 and NLRP1 seemed to partly contribute to the development of KD. Further analysis with larger samples of another independent set would be needed to find confirmative results.

Genetic polymorphisms in the CD40 ligand gene and Kawasaki disease

BACKGROUND

Although some previous studies have reported that genetic and immunological factors play important roles in the pathogenesis of Kawasaki disease (KD), the etiological factors of this enigmatical pediatric disease are still poorly understood.

PURPOSE

This study aims to investigate whether polymorphisms of the CD40 ligand (CD40L) gene are associated with KD and the development of coronary artery lesions (CAL) in the Taiwanese children.

MATERIALS AND METHODS

The CD40L -3459 A/G and IVS4+121 A/G single nucleotide polymorphisms (SNPs) were genotyped in 167 children with KD and 1,010 ethnically matched healthy controls by TaqMan assay.

RESULTS

None of the CD40L polymorphisms was associated with susceptibility or CAL development of KD, and this finding was supported by the haplotype analysis.

CONCLUSION

In summary, these results provide little support for specific CD40L SNPs in the susceptibility or CAL development of KD in Taiwanese children. However, it will be necessary to validate or replicate this association in other independent large-size ethnic groups.

Lack of association of the vascular endothelial growth factor gene polymorphisms with Kawasaki disease in Taiwanese children

INTRODUCTION

Kawasaki disease (KD) is an acute febrile vasculitis of unknown etiology that mainly occurs in infants and children. Clinical and histopathologic findings suggest that vascular endothelial growth factor (VEGF) is involved in the coronary artery lesions (CALs) development in KD. This study hypothesized that specific VEGF gene polymorphisms and their haplotypes are associated with KD susceptibility and CAL development in Taiwanese children.

SUBJECTS AND METHODS

The VEGF -2578 A/C, -634 G/C, and +936 C/T single-nucleotide polymorphisms (SNPs) were genotyped in 156 children with KD and 672 ethnically matched healthy controls using the Pre-Developed TaqMan Allelic Discrimination Assay.

RESULTS

No significant differences in genotype, allele, carrier, and haplotype frequencies of the three SNPs were found between healthy controls and children with KD or between patients with and without CAL.

CONCLUSION

Our data suggest that VEGF -2578 A/C, -634 G/C, and +936 C/T SNPs do not confer increased susceptibility to KD or to CAL development.

Levels of intra- and extracellular heat shock protein 60 in Kawasaki disease patients treated with intravenous immunoglobulin

Immune reactivity to autologous heat shock protein 60 (HSP60) has been reported to be associated with a favorable prognosis in autoimmune diseases. To provide a clue for the possible role of HSP60 in Kawasaki disease (KD), we investigated the levels of intra- and extracellular HSP60 in the course of KD. In KD patients, autologous HSP60 was abundantly expressed in CD11c(+) cells during the acute phase and subsequently decreased during the subacute phase. Most of HSP60-expressing CD11c(+) cells observed in the acute phase was composed of CD11c(low) cells instead of CD11c(high) cells, which were dominant in the subacute phase. In contrast, circulating HSP60 levels were higher in the subacute phase than those in the acute phase, reflecting higher level of HSP60 exposure to the immune system of patients during recovery. These changes in the levels of intra- and extracellular HSP60 were not observed in patients with other febrile diseases. The observed features of HSP60 expression in patients with KD are in favor of a role for autologous HSP60 as a regulator for control of inflammation, rather than a proinflammatory mediator in KD.

Genetic Variations of HLA-DRB1 and Susceptibility to Kawasaki Disease in Taiwanese Children

Although some previous studies have reported that genetic and immunologic factors play important roles in the pathogenesis of Kawasaki disease (KD), the etiologic factors of this enigmatic pediatric disease are still poorly understood. The purpose of this study was to investigate whether polymorphisms of the human leukocyte antigen DRB1 (HLA-DRB1) gene are associated with KD and the development of coronary artery lesions (CAL) in Taiwanese children. Genomic DNA was extracted from whole blood samples from 145 children with KD and 331 healthy controls. The HLA-DRB1 gene was genotyped by polymerase chain reaction (PCR) and sequence-based typing assays. We found that the distribution of HLA-DRB1 allele families and alleles in children with KD did not differ from that in healthy controls. Stratified analysis did not demonstrate any association between particular HLA-DRB1 allele families or alleles and the development of CAL in children with KD. These findings suggest that susceptibility to KD and CAL is not associated with the HLA-DRB1 gene in a Taiwanese population. If immunogenetic determinants are involved in this disease and its complications in Taiwanese children, they must involve genes other than HLA-DRB1.

Diagnosis, treatment and outcome of Kawasaki disease in an Australian tertiary setting: a review of three years experience

OBJECTIVE

To examine the patient characteristics, diagnostic criteria, treatment, complications and outcomes of Kawasaki disease (KD) in children diagnosed and treated in an Australian tertiary hospital setting and compare this to previously reported experience.

METHODS

Data were collected prospectively for 14 patients in 2002 and retrospectively for 31 patients in 2000 and 2001. Demographics, clinical features, laboratory features, treatment and outcome details were collected, analysed and compared to previous experience.

RESULTS

The median age at diagnosis was 2.77 years (0.28-8.84) and diagnosis was made after a mean 6.1 days of fever. Twenty-eight patients (62.2%) had classical KD and those with less than four criteria were younger than those with four or more criteria (P = 0.04). Patients were treated with intravenous immunoglobulin and aspirin. Twelve (26.7%) required re-treatment. Re-treatment was associated with treatment within 5 days of fever onset (P = 0.03). Twelve patients (27.3%) developed coronary artery abnormalities and the development of such abnormalities was associated with lower serum albumin at diagnosis (P = 0.008) and need for re-treatment (P = 0.03). There was no difference in coronary outcome between classical and incomplete presentations. Only two patients had coronary lesions at 12 months follow-up.

CONCLUSIONS

We found a trend towards earlier diagnosis and treatment of KD in the tertiary hospital setting, which may reflect heightened physician awareness of the disease. Our study confirms that children who present with incomplete disease are at risk of coronary artery abnormality. We recommend that clinicians continue to maintain high levels of suspicion, even in the absence of the complete clinical picture of KD, particularly in infants below 1 year of age.

Epidemiologic picture of Kawasaki disease in Korea, 2000-2002

BACKGROUND

The aim of this study was to investigate the incidence rate and epidemiologic patterns of Kawasaki disease in Korea for a 3 year period during 2000 to 2002.

METHODS

An epidemiologic survey on Kawasaki disease was retrospectively performed. The questionnaire was sent to all 112 hospitals having pediatric residency programs, and obtained data were analyzed.

RESULTS

The 9150 cases of Kawasaki disease from 92 hospitals which responded (response rate, 82.1%) included 5515 males and 3635 females (male : female ratio, 1.52:1). The incidence rate per 100,000 children <5 years old was 73.7 in 2000, and increased to 90.8 in 2001, and 95.5 in 2002 (average rate, 86.4). The monthly number of patients was slightly higher in May, June and July. Their mean age of onset, the proportion of sibling cases, and a rate of recurrent cases were 30.5 months, 0.17%, and 2.9%, respectively. Coronary arterial abnormalities occurred in 18.6% of cases including dilatations of 17.3% and aneurysms of 3.1%.

CONCLUSION

The average annual incidence, 86.4/100 000 in children <5 years old is the second highest rate in the world.

The throat flora and its mitogenic activity in patients with Kawasaki disease

The etiology of Kawasaki disease (KD) remains unknown, although some infectious organism has been suggested as the cause. Recent studies suggest that some bacterial toxins with superantigen activity are involved in its pathogenesis, but no specific bacterial toxin has yet been identified. Throat swabs for bacterial culture were obtained from 21 patients with KD and 20 with other febrile illnesses as controls. Mitogenic activity in culture supernatants obtained from individual bacterial strains was measured by lymphocyte proliferation assay. Sixty-one bacterial strains were isolated from KD patients, and 62 strains from control patients. There was no apparent difference in bacterial species in the throat flora between KD patients and febrile controls. Moreover, total and individual mitogenic activity of strains from KD patients was no greater than that of strains from febrile controls. The bacterial superantigen activity of throat flora may not play a major role in the pathogenesis of KD.

Serum Anti-Yersinia Antibody in Chinese Patients with Kawasaki Disease

BACKGROUND

Many infectious agents have been implicated as an etiology to develop Kawasaki disease (KD). In Taiwan, studies on the relationship between Yersinia and KD have not been reported.

METHODS

We measured sera for anti-Yersinia antibodies by using enzyme immunoassay (EIA) in 31 patients with KD and 60 healthy children (HC). Yersinia strains included Y. pseudotuberculosis I, II, III, IV, V, VI and Y. enterocolitica O3, O8 and O9.

RESULTS

Data of 31 patients with KD showed that for the IgG antibody, serum anti-Y. pseudotuberculosis II, III, Y. O8 and O9 antibody were significantly higher when compared to the HC. Except for Y. pseudotuberculosis IV, all other Yersinia strains of either IgA or IgM antibodies increased significantly in patients with KD vs. the HC. If we compared the number of patients who had significant elevation of OD and those of HC, we found IgA anti-Yersinia antibodies (PST I, PST II, O3, O8, O9), IgM (PST VI, O8) and IgG (PST II, O8, O9) were significantly elevated in KD patients than in HC. A significant relationship was present between KD with myocarditis and increased anti-Yersinia antibody titer.

CONCLUSIONS

The findings in this study suggest that preceding Yersinia infection may play a role in the pathogenesis of KD. Further study of the relationship between KD with myocarditis and increased anti-Yersinia antibody is needed.

Bacteriophages in autoimmune disease and other inflammatory conditions

There are several autoimmune diseases and other inflammatory conditions where an infectious aetiology is suggested by the epidemiology, clinical course and pathological findings. Many candidate bacteria and viruses have been considered as potential aetiological agents but mostly without firm proof. Bacteriophages are viruses that infect bacteria and may be found wherever bacteria are located, but would not be detected unless specifically sought. They have not previously been considered to be pathogens. Bacteriophages are immunogenic and therefore could play a role in the pathogenesis of autoimmune and other inflammatory diseases by acting as antigens on epithelial surfaces, bound to antibody as immune complexes, through molecular mimicry or possibly as superantigens.

An unusual pattern of arthritis in a child with Kawasaki syndrome

Arthritis is reported in one-third of cases with Kawasaki syndrome. It may have an early or a late onset form. We present a 15-month-old-girl who had been referred with complaints of pain and swelling in her left shoulder. Physical examination revealed bulbar conjunctival injection, erythematous lips and pharynx, strawberry tongue, erythematous rash, edema and erythema of the left shoulder, left knee, right elbow and right wrist, and moderate distress in the left shoulder and left hip. She was diagnosed with Kawasaki syndrome, and intravenous immunoglobulin infusion (IVIG) 2 g/kg and aspirin (100 mg/kg/day) were instituted. The patient had two additional episodes of arthritis involving the hip joint on the 8th day, and the shoulder and metacarpophalangeal (MCP) and interphalangeal (IP) joints of her right hand on the 15th day. Turbid material was aspirated in both instances; Gram and Wright's staining of this material showed many leukocytes but no bacteria. A second dose of IVIG (1 g/kg) was given. At the end of the third week all extremities were painless, with a normal range of motion. Arthritis in our patient was the presenting sign, having a 'septic arthritis mimicking' and 'biphasic' pattern. Although the patient presented with severe and recurrent arthritis, which is significantly correlated with severe multisystem disease and the presence or development of coronary artery aneurysm, the response to IVIG was excellent.

Epidemiology of the vasculitides

In summary, systemic vasculitides constitute a heterogeneous group of overlapping diseases that are somewhat more common than previously considered. Although the causes of vasculitis are largely unknown, epidemiologic studies have implicated geographic, genetic, and environmental factors. Ethnicity, various genes such as those of the MHC, gender, and environmental factors seem to account for the different incidence rates of these syndromes. GCA is the most common vasculitis in elderly people from Western countries. Small-sized cutaneous vasculitides, particularly HSP in children and HV in adults, are also common diseases. Increased physician awareness and the routine use of ANCA tests may contribute to an increase in the recognition of conditions such as WG and MPA.

Kawasaki-like syndromes associated with human immunodeficiency virus infection

Kawasaki disease is an acute febrile vasculitic syndrome of early childhood. It is very rarely seen in adults. Among the adult patients with Kawasaki disease who have been described, a disproportionate number are infected with human immunodeficiency virus (HIV). This suggests that the immunocompromised state may predispose individuals to this syndrome. We report our experience with 2 HIV-positive patients who presented with Kawasaki-like syndromes and review the published literature on HIV-positive patients with similar syndromes.

Incidence survey of Kawasaki disease in 1997 and 1998 in Japan

OBJECTIVE

To describe the results of a nationwide epidemiologic survey of Kawasaki disease for the 2-year period 1997 and 1998.

DESIGN

We sent a questionnaire to all hospitals with 100 beds or more throughout Japan (2663 hospitals) requesting data on patients with Kawasaki disease. Study items included name, sex, date of birth, date of initial hospital visit, diagnosis, address, recurrence, sibling cases, gammaglobulin treatment, and cardiac lesion in the acute stage or 1 month after onset.

RESULTS

Of the 2663 hospitals, 68.5% responded, reporting 12 966 patients-7489 males and 5477 females. Of the total patients reported, 6373 (incidence rate of 108.0 per 100 000 children <5 years old) occurred in 1997, and 6593 (111.7) in 1998. More than one half of the patients (54.9%) were <2 years old and 81.6% were <4 years old. In males, the incidence rates of cardiac lesions were 27.2 in the acute stage and 10.1 a month after onset. In females, the rates were 16.7 and 5.2, respectively. The incidence rates of cardiac lesions were highest in the youngest age group (<6 months old) both in the acute stage and 1 month after onset. The rates decreased with increasing ages. Although frequency of giant aneurysms was not high at the acute stage, it did not decrease 1 month after onset.

CONCLUSION

The incidence rates have been steadily increasing for 11 years since 1987. The rate in 1998 was over 1.5 times higher than that in 1987. The age and sex distributions were identical in each survey. Although most of the cardiac lesions at the acute stage decreased to half or less 1 month after onset, giant aneurysms did not decrease and existed persistently after 1 month.

Results of the nationwide epidemiologic survey of Kawasaki disease in 1995 and 1996 in Japan

OBJECTIVE

The objective of the study is to describe recent epidemiologic patterns of Kawasaki disease based on information included in patient records that had been obtained through a nationwide hospital survey in Japan.

METHODS

A questionnaire and diagnostic criteria for Kawasaki disease that had been approved by the Kawasaki Disease Research Committee were sent to all pediatric departments of hospitals (2638 hospitals) with a bed capacity of at least 100. The subjects all were new patients who were treated during a 2-year period from 1995 to 1996.

RESULTS

A total of 12 531 children contracted the disease during the observation period. The incidence was 102.6 for 1995 and 108.0 for 1996 per 100 000 children younger than age 5 years. The male:female ratio was 1.37. The age distribution pattern showed a peak near 6 months of age. Geographic variations in the incidence suggested the existence of local outbreaks. Cardiac sequelae were seen in 12% of the patients.

CONCLUSION

More than 6000 patients suffered from Kawasaki disease each year, and its annual incidence is increasing steadily. The probable existence of local outbreaks is worthy of note. Other epidemiologic patterns were unchanged from previous years.

Leukocyte counts in patients with Kawasaki disease: from the results of nationwide surveys of Kawasaki disease in Japan

In the latest survey of Kawasaki disease in Japan, questionnaires on maximal leukocyte counts of the patients were included to clarify whether leukocyte counts could be of value for the diagnosis and prediction of outcome. A questionnaire form and diagnostic guidelines for Kawasaki disease were sent to all pediatric departments of hospitals with > or = 100 beds throughout Japan, and information including maximal leukocyte counts was obtained on patients with Kawasaki disease diagnosed during the 2-y period from January 1993 to December 1994. Of the 11,458 patients diagnosed during the 2-y period, maximal leukocyte counts were reported in 11,062 patients (96.5%). The mean value and the distribution of maximal leukocyte counts were lower in the age group under 1 y. The mean values and the distribution of leukocyte counts were lowest in suspected cases among three diagnostic categories: typical cases of Kawasaki disease, atypical cases, and suspected cases. The mean values of maximal leukocyte counts of the patients with cardiac sequelae were significantly higher than those without cardiac sequelae in each age group. The proportion of patients with cardiac sequelae increased with leukocyte counts in each age group. The Receiver/Response Operating Characteristic (ROC) curve for maximal leukocyte counts in Kawasaki disease revealed that the accuracy of maximal leukocyte counts for prediction of cardiac sequelae was highest in the age group < 6 months, and the most accurate cut-off point was 16 x 10(9)/l. The strongest association between higher leukocyte counts (> or = 16 x 10(9)/l) and cardiac sequelae was observed in the age group < 6 M. A large-scale analysis of leukocyte counts in patients with Kawasaki disease revealed age-dependent relationship between maximal leukocyte counts, diagnostic categories and outcome. Maximal leukocyte counts may be helpful for the prediction of outcome with the consideration of age.

Passive surveillance for Kawasaki disease in San Diego County

BACKGROUND

Kawasaki disease (KD) is the most common cause of acquired heart disease in children in the United States. Epidemiologic surveillance is conducted to monitor baseline incidence of the disease and to identify epidemics. The aim of this study was to evaluate a passive surveillance system for reporting cases of KD in San Diego County to the local, state and national health authorities.

METHODS

We performed a retrospective review of a 2-year period to identify the number of patients who met criteria of the Centers for Disease Control and Prevention for diagnosis of KD and who were successfully reported to the county, state and national databases.

RESULTS

The total number of KD patients for 1994 and 1995 was determined by retrospective review of medical record discharge diagnosis codes. Of the 28 San Diego County residents diagnosed with KD in 1994, 24 (86%) met CDC criteria and 15 (63%) of these eligible patients were reported to the county and state health authorities. Of the 41 residents in 1995, 34 (83%) met CDC criteria and 22 (65%) were reported to the above agencies. No patient in either 1994 or 1995 was reported by local or state health authorities to the CDC.

CONCLUSION

Passive surveillance for KD in San Diego County resulted in the reporting of approximately two-thirds of the eligible patients at the county and state levels but completely failed to report any documented cases to the CDC. Implementation of a sentinel hospital reporting system should be considered as a preferred alternative to national passive surveillance in the effort to track total numbers of patients and to follow disease trends over time.