Genomes of the Orestias pupfish from the Andean Altiplano shed light on their evolutionary history and phylogenetic relationships within Cyprinodontiformes.

BACKGROUND: To unravel the evolutionary history of a complex group, a comprehensive reconstruction of its phylogenetic relationships is crucial. This requires meticulous taxon sampling and careful consideration of multiple characters to ensure a complete and accurate reconstruction. The phylogenetic position of the Orestias genus has been estimated partly on unavailable or incomplete information. As a consequence, it was assigned to the family Cyprindontidae, relating this Andean fish to other geographically distant genera distributed in the Mediterranean, Middle East and North and Central America. In this study, using complete genome sequencing, we aim to clarify the phylogenetic position of Orestias within the Cyprinodontiformes order. RESULTS: We sequenced the genome of three Orestias species from the Andean Altiplano. Our analysis revealed that the small genome size in this genus (~ 0.7 Gb) was caused by a contraction in transposable element (TE) content, particularly in DNA elements and short interspersed nuclear elements (SINEs). Using predicted gene sequences, we generated a phylogenetic tree of Cyprinodontiformes using 902 orthologs extracted from all 32 available genomes as well as three outgroup species. We complemented this analysis with a phylogenetic reconstruction and time calibration considering 12 molecular markers (eight nuclear and four mitochondrial genes) and a stratified taxon sampling to consider 198 species of nearly all families and genera of this order. Overall, our results show that phylogenetic closeness is directly related to geographical distance. Importantly, we found that Orestias is not part of the Cyprinodontidae family, and that it is more closely related to the South American fish fauna, being the Fluviphylacidae the closest sister group. CONCLUSIONS: The evolutionary history of the Orestias genus is linked to the South American ichthyofauna and it should no longer be considered a member of the Cyprinodontidae family. Instead, we submit that Orestias belongs to the Orestiidae family, as suggested by Freyhof et al. (2017), and that it is the sister group of the Fluviphylacidae family, distributed in the Amazonian and Orinoco basins. These two groups likely diverged during the Late Eocene concomitant with hydrogeological changes in the South American landscape.

Neonatal Abstinence Syndrome and Corresponding Pharmacotherapy Approaches from 2 University-affiliated Neonatal Intensive Care Units in Puerto Rico (2018-2020).

OBJECTIVE: Neonatal abstinence syndrome (NAS) is a set of drug withdrawal symptoms suffered by neonates exposed to drugs in utero. Several studies have widely described NAS incidence and treatment approach; however, little is known regarding the incidence and manifestations of this disease in Puerto Rico (PR). The principal aim of this study was to describe NAS incidence in the neonatal units of hospitals affiliated with the University of PR in terms of occurrence, clinical manifestations, and treatment approaches. METHODS: Our study evaluated the medical records of NAS babies diagnosed from 2018 through 2020 at 2 hospitals affiliated with the University of PR Medical Sciences Campus. Descriptive and inferential statistics were employed to analyze trends. RESULTS: We identified 12 neonates diagnosed with NAS, 5 with low birthweights (<2500 g); for a NAS incidence of 2 cases per 1000 admitted for the 3 years of recollected data. The urine toxicology results revealed that 9 had experienced intrauterine polydrug exposure. Phenobarbital loading dose were determined on the day of diagnosis (indicated by Finnegan score). The first manifestation of NAS symptoms varied: 8 neonates showed symptoms within 48 hours after birth, whereas 4 had withdrawal symptoms within 72-120 hours of their births. Differences between dosing practices and guidelines were observed, ranging from a 0.69% to a 25% difference during treatment initiation. CONCLUSION: Further research on the incidence of NAS in PR (national level) is needed for a deeper understanding that we hope will lead to the development of enhanced treatment protocols in PR.

Estrategias para garantizar la seguridad del paciente crítico / Strategies to ensure the critical patient safety

Objetivo: Identificar las estrategias para garantizar la seguridad del paciente crítico. Método: Revisión integradora, cuya búsqueda fue realizada en mayo del 2022 haciendo uso de las fuentes de datos: MEDLINE, SciELO, WOS, LILACS, Scopus e IBECS. El análisis y síntesis se construyó a partir de los resultados encontrados, buscando agruparlos por categorías en función de la similitud de contenido. Resultados: Se encontraron 377 artículos, luego se procedió a aplicar los criterios de inclusión y la lectura exhaustiva, resultando una muestra de 13 artículos. Los resultados fueron clasificados en cinco categorías: Prevención de la neumonía asociada a la ventilación mecánica; Seguridad en la administración y gestión de medicamentos; Prevención de las lesiones por presión; Programa educativo orientado a la seguridad del paciente en cuidados intensivos, y Reflexiones del equipo de salud con respecto a cultura de seguridad.Conclusiones: Este estudio contribuye a identificar de forma integral las diversas estrategias cuyos resultados demostraron un cambio positivo en la prevención de eventos adversos y el fortalecimiento en la seguridad en la atención sanitaria (AU)

Objective: Identify the strategies to guarantee the safety of the critically ill patient. Method: Integrative review, search carried out in May 2022 using the data sources: MEDLINE, SciELO, WOS, LILACS, Scopus and IBECS. The analysis and synthesis were built from the results found, seeking to group them by categories based on the similarity of content. Results: 377 articles were found, thenthe inclusion criteriaand exhaustive reading were applied, resulting in a sample of 13 articles. The results were classified into five categories: Prevention of pneumonia associated with mechanical ventilation; Safety in the administration of management of medicines; Prevention of pressure injuries; Educational program oriented to patient safety in intensive care and; Reflections of the health team regarding safety culture. Conclusions: This study contributes to comprehensively identify the various strategies whose results demonstrated a positive change in the prevention of adverse events and strengthening of safety in health care (AU)

Prevalence and molecular identification of zoonotic Anisakis and Pseudoterranova species in fish destined to human consumption in Chile.

Zoonotic larvae of the family Anisakidae found in several fish species represent a serious risk in public health since they may cause food-borne anisakidosis in humans. Chile has culinary preferences including eating raw fish in many traditional preparations. In the present study, a total of 180 fish specimens representing three different fish species, i.e., Chilean hake (Merluccius gayi), snoek (Thyrsites atun), and sea bream (Brama australis), were caught at central coast of Chile. Parasitological examination was performed on musculature and abdominal cavity for subsequent extraction and quantification of anisakid larvae. Estimation of infection parameters, such as prevalence, was performed indicating 100% (CI: 0.94-1.0) prevalence of anisakid L3 in Chilean hakes and snoeks. Moreover, sea breams reached a prevalence of 35% (CI: 0.23-0.48). Prevalence of anisakid larvae in muscle was also analyzed showing values of 18.6% (CI: 0.097-0.309) in Chilean hakes, 15% (CI: 0.07-0.26) in snoeks, and 1.7% (CI: 0-0.089) in sea breams. Meanwhile, prevalence of anisakid larvae in internal organs showed highest values for peritoneum (100% and 83.3%) for snoeks and Chilean hakes, respectively, for liver (96.7%) and gonads (86.6%) in Chilean hakes, and for intestine (98.3%) in snoeks. Molecular analysis of collected anisakid L3 unveiled presence of two potentially zoonotic nematode species, i.e., Pseudoterranova cattani and Anisakis pegreffii. P. cattani was found in Chilean hakes and snoeks being the first molecular host species report for Chilean snoeks. Besides, A. pegreffii was also identified in these species being the first molecular report on this regard. These findings are relevant for better understanding of epidemiology of anisakiasis in Chilean coasts and for public health issues considering potential risk of human population due to its culinary preferences in eating raw fish.

Antifungal susceptibility of Malassezia pachydermatis isolated from the external auditive conduct from dogs, in central Chile.

Background: External otitis is common in dogs, and one of the main agents involved is Malassezia pachydermatis, a yeast belonging to the otic microbiota. Empirical treatment can fail; therefore, it is essential to know the antifungal susceptibility profile to prescribe appropriate treatment, a fact scarcely reported in Chile. Aim: This study aimed to determine the antifungal sensitivity of M. pachydermatis isolated from the external auditory canal of dogs in central Chile. Methods: Ear swabs from 30 dogs (15 healthy and 15 with external otitis) were used. Samples were subjected to cytology and fungal culture. The antifungal susceptibility was determined according to clinical and laboratory standards institute (CLSI) document M44A-2 using the disk diffusion test from amphotericin B, Caspofungin, fluconazole, nystatin, clotrimazole, and voriconazole were used. Results: The prevalence of M. pachydermatis was 66.7% from 8 healthy dogs and 12 with otitis. While fungal culture was not associated with the patient's clinical condition (p = 0.24), the yeast count by cytology was significantly higher in dogs with otitis (p = 0.003). The strains were sensitive to all antifungals except for Caspofungin, where 55% of the strains were resistant. Conclusion: Malassezia pachydermatis is isolated more frequently in dogs with otitis, and the ear cytological examination is useful to differentiate colonized dogs versus dogs with otitis. In addition, most antifungals in vitro are active against this yeast, except Caspofungin, an antifungal used in human medicine. This situation should be further monitored in epidemiological programs to evaluate the possible impact on Chilean public health.

Genome sequencing and transcriptomic analysis of the Andean killifish Orestias ascotanensis reveals adaptation to high-altitude aquatic life.

Orestias ascotanensis (Cyprinodontidae) is a teleost pupfish endemic to springs feeding into the Ascotan saltpan in the Chilean Altiplano (3,700 m.a.s.l.) and represents an opportunity to study adaptations to high-altitude aquatic environments. We have de novo assembled the genome of O. ascotanensis at high coverage. Comparative analysis of the O. ascotanensis genome showed an overall process of contraction, including loss of genes related to G-protein signaling, chemotaxis and signal transduction, while there was expansion of gene families associated with microtubule-based movement and protein ubiquitination. We identified 818 genes under positive selection, many of which are involved in DNA repair. Additionally, we identified novel and conserved microRNAs expressed in O. ascotanensis and its closely-related species, Orestias gloriae. Our analysis suggests that positive selection and expansion of genes that preserve genome stability are a potential adaptive mechanism to cope with the increased solar UV radiation to which high-altitude animals are exposed to.

Changes in Treatments and Outcomes After Implementation of a National Universal Access Program for Juvenile Idiopathic Arthritis.

OBJECTIVE: To evaluate the clinical and demographic characteristics of patients with juvenile idiopathic arthritis (JIA) in Chile and compare treatments and outcomes before and after the introduction in 2010 of the Explicit Health Guarantees (GES) for JIA, a national universal access program for diagnosis and treatment of this condition. METHODS: The clinical records of 280 patients with JIA followed at a private tertiary academic health network between 2007 and 2018 were reviewed. RESULTS: Seventy percent of patients with JIA were female, mean age at diagnosis was 8.5 ± 4.8 years and mean follow-up was 4.0 ± 3.7 years. After GES implementation (post-GES), time to evaluation by pediatric rheumatologist and diagnostic delay were significantly reduced (15.0 ± 4.5 vs 9.0 ± 4.2 months, P = 0.004). In addition, use of magnetic resonance imaging significantly increased post-GES (P < 0.001). In terms of JIA treatments, before GES implementation, no patients received biologics. Of the 67 patients diagnosed before 2010 with continued follow-up at our center, 34% began biologic treatment after GES implementation. Of 196 patients diagnosed post-GES, 46% were treated with biologics. JIA remission rates were significantly higher in patients diagnosed post-GES compared to pre-GES (43% vs 29%, P = 0.02). Post-GES, we observed a significant decrease in uveitis complications among JIA patients (45% vs 13%, P = 0.04). CONCLUSION: The implementation of a national government-mandated universal access program for guaranteed JIA diagnosis and treatment led to earlier access to a pediatric rheumatologist and JIA diagnosis, increased rates of treatment with biologic drugs, higher rates of clinical remission, and lower rates of uveitis complications in Chilean children with JIA.

Post-thawing Sperm Quality in Chilean Purebred Stallions: Effect of Age and Seasonality.

In this work, we investigated the influence of age and seasonality on sperm motility and DNA fragmentation in post-thawing semen from Chilean Purebred Stallions (CPS), a horse breed presenting the oldest genealogy record in South America with an interesting reproductive industry. Despite that semen from aged CPS is frozen all year round, there is a lack of studies characterizing the breed semen freezability in accordance with age and seasonality. Twenty fertile CPS were grouped into the young group, the middle group, and the aged group. Ten ejaculates from each stallion were obtained by using an artificial vagina during summer (December) and winter (July) and directly frozen. Subsequently, the frozen semen was thawed and analyzed by a computer-assisted semen analysis and flow cytometer assessing progressive motility, mean velocity, and DNA fragmentation spermatozoa. Kruskal-Wallis test and Pearson's correlation were used to determine statistical differences among groups and correlation among variables (P ≤ .05). Both spermatozoa motility traits decreased progressively in accordance with age and seasonality, showing the lowest values in the aged group during winter and the highest values in the young group during summer. Deoxyribonucleic acid fragmentation increased significantly in accordance with age and seasonality being highest in the aged group during winter and lowest in the young group during summer. Post-thawing sperm quality showed a negative correlation with the age of the stallions and a positive correlation with the normal sperm morphology before freezing. These results allow the conclusion that age and seasonality are important factors that need to be considered during the selection of CPS for reproductive programs.

Clinical characterization of Chilean patients with IgE-mediated food allergy. / Caracterización clínica de pacientes chilenos con alergia alimentaria mediada por IgE.

BACKGROUND: Food allergy (FA) is an entity of high and growing prevalence, which can be mediated by IgE or cellular immunity. It can have a wide range of symptoms and be triggered by multiple food antigens, which vary in different geographical areas. OBJECTIVES: To describe clinical characteristics of Chilean patients with IgE-mediated FA. PATIENTS AND METHOD: Retrospective review of patients with IgE-mediated FA treated at a tertiary healthcare center in Santiago, Chile, between 2006 and 2016. Demographic characteristics, clinical manifestations, and trigger foods were evaluated. RESULTS: A to tal of 282 patients diagnosed with IgE-mediated FA were included. 89% had FA onset before 18 years of age and most of these before one year of age (median of age: one year; range: one month-55 years). The most common clinical manifestations were hives, angioedema, dyspnea, and vomiting. 40% had symptoms compatible with anaphylaxis. The foods most frequently involved were egg, cow's milk, peanut, shellfish, walnut, tomato, wheat, avocado, fish, and legumes. Egg, cow's milk, and peanut allergies were the most frequent at pediatric age, while seafood allergy was the most frequent among adults. CONCLUSION: Foods causing IgE-mediated FA in Chile were similar to those described in other countries, although the frequency of tomato and avocado allergy, which are unusual in international series, stands out. Anaphylaxis incidence was high, emphasizing the need for epinephrine autoinjec tors in Chile.

Caracterización clínica de pacientes chilenos con alergia alimentaria mediada por IgE / Clinical characterization of Chilean patients with IgE-mediated food allergy

INTRODUCCIÓN: La alergia alimentaria (AA) es una entidad de elevada y creciente prevalencia, pudiendo ser mediada por IgE o inmunidad celular. Puede presentar amplia sintomatología y ser gatillada por múltiples antígenos alimentarios, lo que varía en diversas zonas geográficas. OBJETIVO: Describir las características clínicas de pacientes chilenos con AA IgE-mediada. PACIENTES Y MÉTODO: Revisión retrospectiva de pacientes con AA IgE-mediada atendidos en un centro terciario de salud de Santiago, Chile entre los años 2006 y 2016. Se evaluaron características demográficas, manifestaciones clínicas y alimentos gatillantes. RESULTADOS: Se incluyeron 282 pacientes con diagnóstico de AA IgE-mediada. El 89% debutó con AA antes de los 18 años de edad y de estos, la mayoría antes del año (mediana: 1 año; rango: 1 mes - 55 años). Las manifestaciones clínicas más frecuentes fueron urticaria, angioedema, disnea y vómitos. Un 40% tenía historia compatible con anafilaxia. Los alimentos más frecuentes fueron huevo, leche de vaca, maní, mariscos, nuez, tomate, trigo, palta, pescados y legumbres. Alergia a huevo, leche de vaca y maní fueron más frecuentes en edad pediátrica, mientras que en adultos fueron los mariscos. CONCLUSIONES: Los alimentos causantes de AA IgE-mediada en Chile fueron similares a los descritos en otros países, aunque destaca la elevada frecuencia de alergia a tomate y palta, poco habituales en series internacionales. La incidencia de anafilaxia fue alta, lo que instala la necesidad de contar con autoinyectores de adrenalina a nivel nacional.

BACKGROUND: Food allergy (FA) is an entity of high and growing prevalence, which can be mediated by IgE or cellular immunity. It can have a wide range of symptoms and be triggered by multiple food antigens, which vary in different geographical areas. OBJECTIVES: To describe clinical characteristics of Chilean patients with IgE-mediated FA. Patients and Method: Retrospective review of patients with IgE-mediated FA treated at a tertiary healthcare center in Santiago, Chile, between 2006 and 2016. Demographic characteristics, clinical manifestations, and trigger foods were evaluated. RESULTS: A to tal of 282 patients diagnosed with IgE-mediated FA were included. 89% had FA onset before 18 years of age and most of these before one year of age (median of age: one year; range: one month-55 years). The most common clinical manifestations were hives, angioedema, dyspnea, and vomiting. 40% had symptoms compatible with anaphylaxis. The foods most frequently involved were egg, cow's milk, peanut, shellfish, walnut, tomato, wheat, avocado, fish, and legumes. Egg, cow's milk, and peanut allergies were the most frequent at pediatric age, while seafood allergy was the most frequent among adults. CONCLUSION: Foods causing IgE-mediated FA in Chile were similar to those described in other countries, although the frequency of tomato and avocado allergy, which are unusual in international series, stands out. Anaphylaxis incidence was high, emphasizing the need for epinephrine autoinjec tors in Chile.

The Gut Microbiota of Healthy Chilean Subjects Reveals a High Abundance of the Phylum Verrucomicrobia.

The gut microbiota is currently recognized as an important factor regulating the homeostasis of the gastrointestinal tract and influencing the energetic metabolism of the host as well as its immune and central nervous systems. Determining the gut microbiota composition of healthy subjects is therefore necessary to establish a baseline allowing the detection of microbiota alterations in pathologic conditions. Accordingly, the aim of this study was to characterize the gut microbiota of healthy Chilean subjects using 16S rRNA gene sequencing. Fecal samples were collected from 41 young, asymptomatic, normal weight volunteers (age: 25 ± 4 years; ♀:48.8%; BMI: 22.5 ± 1.6 kg/m2) with low levels of plasma (IL6 and hsCRP) and colonic (fecal calprotectin) inflammatory markers. The V3-V4 region of the 16S rRNA gene of bacterial DNA was amplified and sequenced using MiSeq Illumina system. 109,180 ± 13,148 sequences/sample were obtained, with an α-diversity of 3.86 ± 0.37. The dominant phyla were Firmicutes (43.6 ± 9.2%) and Bacteroidetes (41.6 ± 13.1%), followed by Verrucomicrobia (8.5 ± 10.4%), Proteobacteria (2.8 ± 4.8%), Actinobacteria (1.8 ± 3.9%) and Euryarchaeota (1.4 ± 2.7%). The core microbiota representing the genera present in all the subjects included Bacteroides, Prevotella, Parabacteroides (phylum Bacteroidetes), Phascolarctobacterium, Faecalibacterium, Ruminococcus, Lachnospira, Oscillospira, Blautia, Dorea, Roseburia, Coprococcus, Clostridium, Streptococcus (phylum Firmicutes), Akkermansia (phylum Verrucomicrobia), and Collinsella (phylum Actinobacteria). Butyrate-producing genera including Faecalibacterium, Roseburia, Coprococcus, and Oscillospira were detected. The family Methanobacteriaceae was reported in 83% of the subjects and Desulfovibrio, the most representative sulfate-reducing genus, in 76%. The microbiota of the Chilean individuals significantly differed from those of Papua New Guinea and the Matses ethnic group and was closer to that of the Argentinians and sub-populations from the United States. Interestingly, the microbiota of the Chilean subjects stands out for its richness in Verrucomicrobia; the mucus-degrading bacterium Akkermansia muciniphila is the only identified member of this phylum. This is an important finding considering that this microorganism has been recently proposed as a hallmark of healthy gut due to its anti-inflammatory and immunostimulant properties and its ability to improve gut barrier function, insulin sensitivity and endotoxinemia. These results constitute an important baseline that will facilitate the characterization of dysbiosis in the main diseases affecting the Chilean population.

Correction: Pattern of genetic differentiation of an incipient speciation process: The case of the high Andean killifish Orestias.

[This corrects the article DOI: 10.1371/journal.pone.0170380.].

Pattern of genetic differentiation of an incipient speciation process: The case of the high Andean killifish Orestias.

During the Pleistocene and Holocene, the southwest Andean Altiplano (17°-22°S) was affected by repeated fluctuations in water levels, high volcanic activity and major tectonic movements. In the early Holocene the humid Tauca phase shifted to the arid conditions that have lasted until the present, producing endorheic rivers, lakes, lagoons and wetlands. The endemic fish Orestias (Cyprinodontidae) represents a good model to observe the genetic differentiation that characterizes an incipient speciation process in allopatry since the morphospecies described inhabit a restricted geographic area, with present habitat fragmentation. The genetic diversity and population structure of four endemic morphospecies of Orestias (Cyprinodontidae) found in the Lauca National Park (LNP) analyzed with mitochondrial markers (Control Region) and eight microsatellites, revealed the existence of genetic groups that matches the fragmentation of these systems. High values of genetic and phylogeographic differentiation indices were observed between Chungará Lake and Piacota lagoon. The group composed of the Lauca River, Copapujo and Chuviri wetlands sampling sites showed a clear signal of expansion, with a star-like haplotype network. Levels of genetic differentiation were lower than in Chungará and Piacota, suggesting that these localities would have differentiated after the bottlenecks linked to the collapse of Parinacota volcano. The Parinacota sample showed a population signal that differed from the other localities revealing greater genetic diversity and a disperse network, presenting haplotypes shared with other LNP localities. A mixing pattern of the different genetic groups was evident using the microsatellite markers. The chronology of the vicariance events in LNP may indicate that the partition process of the Orestias populations was gradual. Considering this, and in view of the genetic results, we may conclude that the morphospecies from LNP are populations in ongoing differentiation process.

Impact of Dietary Lipids on Colonic Function and Microbiota: An Experimental Approach Involving Orlistat-Induced Fat Malabsorption in Human Volunteers.

OBJECTIVES: High-fat diets alter gut microbiota and barrier function, inducing metabolic endotoxemia and low-grade inflammation. Whether these effects are due to the high dietary lipid content or to the concomitant decrease of carbohydrate intake is unclear. The aim of this study was to determine whether higher amounts of dietary fat reaching the colon (through orlistat administration) affect the colonic ecosystem in healthy volunteers and the effect of the prebiotic oligofructose (OF) in this model. METHODS: Forty-one healthy young subjects were distributed among four groups: Control (C), Prebiotic (P), Orlistat (O), and Orlistat/Prebiotic (OP). They consumed a fat-standardized diet (60 g/day) during Week-1 (baseline) and after 1 week of washout, Week-3. During Week-3, they also received their respective treatment (Orlistat: 2 × 120 mg/day, OF: 16 g/day, and maltodextrin as placebo). A 72-h stool collection was carried out at the end of Week-1 (T0) and Week-3 (T1). Fecal fat, calprotectin, and short-chain fatty acids (SCFAs) as well as the antioxidant activity of fecal waters (ferric-reducing antioxidant power), fecal microbiota composition (by deep sequencing), and gut permeability (Sucralose/Lactulose/Mannitol test) were determined at these times. RESULTS: Fecal fat excretion was higher in the O (P=0.0050) and OP (P=0.0069) groups. This event was accompanied, in the O group, by an increased calprotectin content (P=0.047) and a decreased fecal antioxidant activity (P=0.047). However, these alterations did not alter gut barrier function and the changes observed in the composition of the fecal microbiota only affected bacterial populations with low relative abundance (<0.01%); in consequences, fecal SCFA remained mainly unchanged. Part of the colonic alterations induced by orlistat were prevented by OF administration. CONCLUSIONS: In the context of an equilibrated diet, the acute exposition of the colonic ecosystem to high amounts of dietary lipids is associated with an incremented excretion of fecal calprotectin and pro-oxidant activity of the colonic content, in the absence of significant changes in the microbiota.

[Geographic distribution of Kawasaki disease throughout Chile]. / Distribución geográfica de la enfermedad de Kawasaki en Chile.

BACKGROUND: Incidence of Kawasaki disease (KD) in Chile is rising, however the distribution of cases throughout Chile is unknown. OBJECTIVE: To describe the epidemiology of KD in Chile between years 2001 and 2011, and study the geographic distribution of KD cases throughout the country. METHODS: We reviewed national hospital discharge databases for KD cases (ICD10 code M30.3) in children < 18 years. KD admission rates per 100,000 children < 5 years were calculated for every commune, health district and region, as a proxy of KD incidence. RESULTS: 1,404 KD cases were registered with a national KD incidence rate of 8.7. KD incidence rate increased significantly from 5.9 in 2001-2003 to 10.4 in 2009-2011 (p < 0.001). Regions IX (Araucanía), Metropolitan and VI (O'Higgins) had the highest KD incidence (12.4, 11.1 and 10.5 respectively), and regions III (Atacama), II (Antofagasta) and XII (Magallanes), had the lowest incidence (0.8, 3.9 and 4, respectively). The Eastern Metropolitan Health District, the population with the highest socioeconomic status in Chile, had the highest KD incidence rate (19.8) and concentrated 23.9% of the country's hospital discharges for KD. CONCLUSION: KD incidence in Chile is heterogeneous, with concentration of caseloads in the central regions and especially in the Eastern Metropolitan Health District. Geographic variations of KD in Chile could be associated with real differences in incidence or with disparities in diagnostic opportunity, and access to specialists and tertiary healthcare centers.