Wastewater surveillance of SARS-CoV-2 genomic populations on a country-wide scale through targeted sequencing.

SARS-CoV-2 surveillance of viral populations in wastewater samples is recognized as a useful tool for monitoring epidemic waves and boosting health preparedness. Next generation sequencing of viral RNA isolated from wastewater is a convenient and cost-effective strategy to understand the molecular epidemiology of SARS-CoV-2 and provide insights on the population dynamics of viral variants at the community level. However, in low- and middle-income countries, isolated groups have performed wastewater monitoring and data has not been extensively shared in the scientific community. Here we report the results of monitoring the co-circulation and abundance of variants of concern (VOCs) of SARS-CoV-2 in Uruguay, a small country in Latin America, between November 2020-July 2021 using wastewater surveillance. RNA isolated from wastewater was characterized by targeted sequencing of the Receptor Binding Domain region within the spike gene. Two computational approaches were used to track the viral variants. The results of the wastewater analysis showed the transition in the overall predominance of viral variants in wastewater from No-VOCs to successive VOCs, in agreement with clinical surveillance from sequencing of nasal swabs. The mutations K417T, E484K and N501Y, that characterize the Gamma VOC, were detected as early as December 2020, several weeks before the first clinical case was reported. Interestingly, a non-synonymous mutation described in the Delta VOC, L452R, was detected at a very low frequency since April 2021 when using a recently described sequence analysis tool (SAM Refiner). Wastewater NGS-based surveillance of SARS-CoV-2 is a reliable and complementary tool for monitoring the introduction and prevalence of VOCs at a community level allowing early public health decisions. This approach allows the tracking of symptomatic and asymptomatic individuals, who are generally under-reported in countries with limited clinical testing capacity. Our results suggests that wastewater-based epidemiology can contribute to improving public health responses in low- and middle-income countries.

Multiple forms of hotspots of tetrapod biodiversity and the challenges of open-access data scarcity.

The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the implementation of conservation actions both locally and globally has progressively been guided by the identification of biodiversity 'hotspots' (areas with exceptional biodiversity). However, different regions of the world differ drastically in the availability of fine-scale data on the diversity and distribution of species, thus limiting the potential to assess their local environmental priorities. Within South America-a megadiverse continent-Uruguay represents a peculiar area where multiple tropical and non-tropical eco-regions converge, creating highly heterogeneous ecosystems, but where the systematic quantification of biodiversity remains largely anecdotal. To investigate the constraints posed by the limited access to biodiversity data, we employ the most comprehensive database for tetrapod vertebrates in Uruguay (spanning 664 species) assembled to date, to identify hotspots of species-richness, endemism and threatened species for the first time. Our results reveal negligible spatial congruence among biodiversity hotspots, and that tetrapod sampling has historically concentrated in only a few areas. Collectively, our study provides a detailed account of the areas where urgent biodiversity monitoring efforts are needed to develop more accurate knowledge on biodiversity patterns, offering government and environmental bodies a critical scientific resource for future planning.

[Active surveillance of febrile seizures associated to DPT vaccines in a sentinel hospital in Uruguay]. / Vigilancia activa de convulsiones febriles vinculadas a vacuna pentavalente en un hospital centinela en Uruguay.

BACKGROUND: Febrile seizures are VAERS often associated with whole-cells Diphtheria-Pertussis-Tetanus vaccines. AIM: To analyze the association of febrile seizures with the administration of pentavalent vaccine in children under two-years-old assisted in the Centro Hospitalario Pereira Rossell (CHPR), in Montevideo during 2014. METHODS: Self-controlled case series study. We included children from Montevideo from two to 24-month-old at the time of admission, with diagnosis of febrile seizure at the time of discharge. We estimated the relative risk in three time periods: 0 to 3 days (risk period), 4 to 14 days (wash-out) and more than 14 days after vaccination (no-risk). RESULTS: We recorded 135 febrile seizures in 114 children, 16 of whom presented two or more events. The total number of events was 7 (5.2%) in risk periods and 8 (5.9%) in wash-out periods. The risk period showed a significantly increased risk (RR = 4.14, CI 95% = [1.73; 8.36]). CONCLUSIONS: This work allowed us to establish a national base line for the risk of febrile seizures associated with pentavalent vaccination, by using for the first time in the country a methodology specifically designed for this goal.

Biodiversidata: An Open-Access Biodiversity Database for Uruguay.

BACKGROUND: The continental and marine territories of Uruguay are characterised by a rich convergence of multiple biogeographic ecoregions of the Neotropics, making this country a peculiar biodiversity spot. However, despite the biological significance of Uruguay for the South American subcontinent, the distribution of biodiversity patterns in this country remain poorly understood, given the severe gaps in available records of geographic species distributions. Currently, national biodiversity datasets are not openly available and, thus, a dominant proportion of the primary biodiversity data produced by researchers and institutions across Uruguay remains highly dispersed and difficult to access for the wider scientific and environmental community. In this paper, we aim to fill this gap by developing the first comprehensive, open-access database of biodiversity records for Uruguay (Biodiversidata), which is the result of a large-scale collaboration involving experts working across the entire range of taxonomic diversity found in the country. NEW INFORMATION: As part of the first phase of Biodiversidata, we here present a comprehensive database of tetrapod occurrence records native from Uruguay, with the latest taxonomic updates. The database provides primary biodiversity data on extant Amphibia, Reptilia, Aves and Mammalia species recorded within the country. The total number of records collated is 69,380, spanning 673 species and it is available at the Zenodo repository: https://doi.org/10.5281/zenodo.2650169. This is the largest and most geographically and taxonomically comprehensive database of Uruguayan tetrapod species available to date and it represents the first open repository for the country.

Leukocyte Profiles Reflect Geographic Range Limits in a Widespread Neotropical Bat.

Quantifying how the environment shapes host immune defense is important for understanding which wild populations may be more susceptible or resistant to pathogens. Spatial variation in parasite risk, food and predator abundance, and abiotic conditions can each affect immunity, and these factors can also manifest at both local and biogeographic scales. Yet identifying predictors and the spatial scale of their effects is limited by the rarity of studies that measure immunity across many populations of broadly distributed species. We analyzed leukocyte profiles from 39 wild populations of the common vampire bat (Desmodus rotundus) across its wide geographic range throughout the Neotropics. White blood cell differentials varied spatially, with proportions of neutrophils and lymphocytes varying up to six-fold across sites. Leukocyte profiles were spatially autocorrelated at small and very large distances, suggesting that local environment and large-scale biogeographic factors influence cellular immunity. Generalized additive models showed that bat populations closer to the northern and southern limits of the species range had more neutrophils, monocytes, and basophils, but fewer lymphocytes and eosinophils, than bats sampled at the core of their distribution. Habitats with access to more livestock also showed similar patterns in leukocyte profiles, but large-scale patterns were partly confounded by time between capture and sampling across sites. Our findings suggest that populations at the edge of their range experience physiologically limiting conditions that predict higher chronic stress and greater investment in cellular innate immunity. High food abundance in livestock-dense habitats may exacerbate such conditions by increasing bat density or diet homogenization, although future spatially and temporally coordinated field studies with common protocols are needed to limit sampling artifacts. Systematically assessing immune function and response over space will elucidate how environmental conditions influence traits relevant to epidemiology and help predict disease risks with anthropogenic disturbance, land conversion, and climate change.

High frequency and extensive genetic heterogeneity of TTSuV1 and TTSuVk2a in PCV2- infected and non-infected domestic pigs and wild boars from Uruguay.

Torque teno sus virus (TTSuV) infection is common worldwide in both healthy and diseased swine and a relationship between this virus and a particular disease in pigs has not been established. This work aimed to investigate the presence of TTSuV1 and TTSuVk2a in Porcine Circovirus type 2 (PCV2)-infected and non-infected domestic pigs and free-living wild boars from Uruguay. Our data evidenced a high frequency of detection and a wide circulation of TTSuV among pig herds and wild boar populations. Furthermore, TTSuV1+TTSuVk2a co-infection was more frequent than single infections in domestic pigs. In addition, we thoroughly characterized at the molecular level TTSuV strains by extensive sequence data analysis. Our findings revealed an extremely high genetic heterogeneity among Uruguayan isolates. On the basis of detailed analyses, we proposed a more comprehensive criterion of TTSuV classification which would contribute to shedding light over the genetic diversity of these viruses worldwide. On the other hand, data obtained suggested that neither TTSuV1 nor TTSuVk2a frequency of infection or viral loads have any correlation with PCV2 infection, health status or age. The role of TTSuV during co-infection with other pathogens and the age-related dynamics of TTSuV infection are currently under debate. Therefore, taking into account the controversial epidemiological data regarding these viruses and their ubiquitous infection, a likely role as components of the host microbiota should be brought into discussion.

Nanopartículas de plata en el tratamiento de la micosis asociada al pie diabético / Silver nanoparticles to treat mycosis associated with diabetic foot / Nanopartículas de prata no tratamento da micose associada ao pé diabético

Resumen: Una proporción importante de infecciones en el pie diabético consisten en onicomicosis y tinea pedis, problema común en el pie, amenazante de la viabilidad del tejido que puede provocar infecciones bacterianas secundarias. Requieren períodos prolongados de tratamiento antimicótico con alta tasas de recaídas y reinfección. Diversos estudios han mostrado la seguridad y eficacia de las nanopartículas de plata (NP Ag) como agente antimicrobiano. Realizamos un estudio donde se evaluó el tratamiento con NP Ag en dermatomicosis del pie de pacientes diabéticos. Método: estudio piloto, abierto, prospectivo, randomizado y controlado en pacientes que asisten a una policlínica de pie diabético. Dieciocho pacientes cumplieron con los criterios de inclusión conformándose dos grupos homogéneos. Ambos grupos recibieron tratamiento estándar que consistió en antimicótico tópico y desbastado mecánico. El grupo intervención utilizó un textil (medias) confeccionadas con hilos con NP Ag. Se realizó control clínico y microbiológico hasta las 12 semanas. Se evaluó el porcentaje de remisión y el tiempo hasta alcanzar el mismo. Resultados: predominó la onicomicosis y el germen Trichophyton rubrum. En el grupo intervención se logró un mayor porcentaje de remisión de lesiones y en un tiempo menor que el grupo control. Conclusiones: el uso de medias confeccionadas con hilos de NP Ag se asoció con una mayor probabilidad de curación completa en un período de 12 semanas a pesar de que el número de pacientes no permitió llegar al nivel de significación estadística, pudiendo contribuir a la prevención de infecciones o úlceras suplementarias en el pie diabético.

Summary: Onychomycosis and tinea pedis represent a significant proportion of infections in the diabetic foot, a common foot problem, and they constitute a threat to the viability of tissues that may provoke secondary bacterial infections. To combat them, antifungal treatments are required for long periods of time, the rates of relapse and reinfection being high. Several studies have proved the safety and effectiveness of silver nano particles (NP Ag) as an antimicrobial agent. A study was conducted to assess nanoparticle agents for foot dermatomycosis in diabetic patients. Method: pilot, open, prospective randomized and controlled study in patients who are assisted in a diabetic foot policlinic. 18 patients complied with the inclusion criteria and two homogeneous groups were formed. Both groups received standard treatment consisting in topic antifungal and mechanical roughing. The intervention groups used a textile (stockings) made with silver nanoparticle threads. Clinical and microbiological control was made during 12 weeks, also assessing the remission percentage and the time it took to achieve it. Resultados: onychomycosis and trichophyton rubrum prevailed. The intervention group showed a greater percentage of remission of lesions in a period of time that was shorter than that of the control group. Conclusions: the use of stockings made with NP Ag threads was associated with a greater probability of complete healing, in a 12-week period, despite the fact that the number of patients was not statistically significant. This could contribute to the prevention of supplementary infections or ulcers in the diabetic foot.

Resumo: Uma proporção significativa de infecções do pé diabético consiste em onicomicose e Tinea pedis, um problema comum nos pés que ameaça a viabilidade do tecido e pode causar infecções bacterianas secundárias. Requerem períodos prolongados de tratamento antifúngico com altas taxas de recidiva e reinfecção. Vários estudos têm demonstrado a segurança e a eficácia das nanopartículas de prata (NP Ag) como agente antimicrobiano. Realizamos um estudo onde o tratamento com NP Ag foi avaliado na dermatomicose do pé de pacientes diabéticos. Método: estudo piloto, aberto, prospectivo, randomizado e controlado em pacientes atendidos em uma policlínica de pé diabético. Dezoito pacientes preencheram os critérios de inclusão, formando dois grupos homogêneos. Ambos os grupos receberam tratamento padrão que consiste em antifúngico tópico e moagem mecânica. O grupo intervenção utilizou um tecido (meias) confeccionado com fios NP Ag. O controle clínico e microbiológico foi realizado até 12 semanas. A porcentagem de remissão e o tempo para alcançá-la foram avaliados. Resultados: predominaram a onicomicose e o germe Trichophyton rubrum. No grupo intervenção, obteve-se maior percentual de remissão das lesões e em menor tempo que o grupo controle. Conclusões: o uso de meias confeccionadas com fios NP Ag esteve associado a uma maior probabilidade de cura completa, no período de 12 semanas, apesar do número de pacientes não permitir atingir o nível de significância estatística, podendo contribuir para a prevenção de infecções ou úlceras adicionais no pé diabético.

Resultados a corto plazo del tratamiento con 131I en el bocio multinodular: valor adicional de la estimulación previa con rhTSH / Short-term results of treatment with 131I in multinodular goiter: additional value of previus stimulation with Recombinant human thyrotropin

OBJETIVO: El yodo radiactivo (131I) es una opción terapeútica segura y eficaz cuando se utiliza solo o con la estimulación previa de TSH recombinante humana (rhTSH) en el tratamiento del bocio multinodular (BMN). En espera de ensayos clínicos que determinen la dosis óptima, demuestren seguridad y confirmen la eficacia, diferentes protocolos se utilizan para aplicar la dosis de 131I. Analizamos la respuesta al tratamiento con una dosis calculada por protocolo mixto (dosis fijas y cálculo por porcentaje de captación) en pacientes con BMN toxico y no toxico en nuestro hospital, en el periodo 2010-2013. MATERIALES Y MÉTODOS: Estudio prospectivo en pacientes con BMN no quirúrgico (BMNNQ) que requerían reducción del volumen glandular y/o tratamiento del hipertiroidismo. Se evaluaron 134 pacientes, 14 cumplieron con los criterios de inclusión (13mujeres) de edad media 71.08 años. Un grupo con BMN toxico, otro grupo con BMN no toxico, un tercer grupo con BMN no toxico estimulado con 0,1 mg de rhTSH previo a la dosis. Se evaluó, función tiroidea, captación tiroidea de 99ᵐTc, volumen tiroideo y síntomas compresivos. Se siguió a los pacientes durante 12 meses. RESULTADOS: Se aplicaron dosis entre 15 y 30 mCi de 131I. Remitió el hipertiroidismo en 6 de 7 pacientes. Hubo una reducción del volumen glandular (p<0.01).Los pacientes con estímulo de 0,1 mg rhTSH, aumentaron el porcentaje de captación de 99ᵐTc a las 24 h en un 32.43±10.61 permitiendo aplicar menor dosis de 131I. La tasa de aparición de hipotiroidismo fue de 7.41 por cada 100 pacientes.mes, mayor en pacientes con BMN toxico tratados con dosis bajas (p-=0.03). Hubo una mejoría subjetiva de la clínica compresiva en todos los pacientes. No hubo eventos adversos. CONCLUSIONES: Una dosis de 131I calculada por protocolo mixto es efectiva y segura para la reducción del volumen glandular y control del hipertiroidismo asociado. La estimulación con rhTSH logra el mismo efecto con una menor dosis administrada.

OBJECTIVE: Radioactive iodine (131I) is a safe and effective therapeutic option when used alone or with prior stimulation of recombinant human Thyrotropin (rhTSH) in the treatment of multinodular goiter (MNG). In absence of clinical trials that determine the optimal dose, demonstrate safety and confirm efficacy, different protocols are used to apply the dose of 131I. We analyze the response to treatment with a dose calculated by mixed protocol (fixed doses and calculation by percentage of uptake) in patients with toxic and non-toxic MNG in our hospital, in the period 2010-2013. MATERIALS AND METHODS: Prospective study in patients with non-surgical MNG that required glandular volume reduction and / or treatment of hyperthyroidism. 134 patients were evaluated, 14 met the inclusion criteria (13 women) of average age 71.08 years. One group with toxic MNG, another group with non-toxic MNG and a third with non-toxic multinodular goiter stimulated with 0.1 mg of rhTSH prior to the dose. Patients were followed for 12 months. Upon following, we assessed Thyroid function, 99ᵐTc thyroid uptake, thyroid volume and compressive symptoms. RESULTS: Doses between 15 and 30 mCi of 131I were applied. We observed hyperthyroidism remission in 6 of 7 patients. There was a reduction in glandular volume (p <0.01) considering all patients. Patients with a stimulus of 0.1 mg rhTSH, increased the percentage of uptake of 99ᵐTc at 24 h by 32.43 ± 10.61, allowing a lower dose of 131I to be applied. The rate of onset of hypothyroidism was 7.41 per 100 patients-month, and was higher in patients with toxic MNG treated with low doses (p = 0.03). There was a subjective improvement of the compression clinic in all patients. No adverse events were observed. CONCLUSIONS: A dose of 131I calculated by a mixed protocol is effective and safe for achieving glandular volume reduction and associated hyperthyroidism control. Stimulation with rhTSH produces the same effect with a lower administered dose.

Resultados del Programa Nacional de Trasplante Hepático del Uruguay a 10 años de su inicio / Results of the National Program of Liver Transplantation in Uruguay 10 years after it was initiated / Resultados do Programa Nacional de Transplante de Fígado do Uruguai 10 anos após seu início

Resumen: Introducción: el trasplante hepático (TH) constituye el tratamiento de elección en pacientes con enfermedades hepáticas severas e irreversibles, sin opción de tratamientos alternativos eficaces. La medición de indicadores de calidad permite detectar problemáticas susceptibles de ser mejoradas a fin de optimizar los resultados. Objetivo: presentar los resultados del Programa Nacional de Trasplante Hepático (PNTH) del Uruguay a 10 años de su implementación y compararlos con los estándares de calidad internacionales. Material y método: estudio retrospectivo de los TH realizados del 14/7/2009 al 14/7/2019. Resultados: N: 190 TH. Edad promedio: 45 años. Sexo: 60% hombres. MELD promedio al TH: 21. Principales indicaciones: cirrosis (59%) y hepatocarcinoma (21%). Mortalidad posoperatoria: 7,4% y perioperatoria: 2,1% (estándares <10% y 1%). Tasa de retrasplante: precoz 3,7% y tardío 4,2% (estándares <5% y 8%). Tasa de reintervención: 13,1% (estándar <10%) y de no función primaria: 2,6% (estándar <2%). Sobrevida: 86,6% al año, 81,8% a 3, 77,4% a 5 y 63,2% a 10 años (estándares >80, 75, 70 y 60%). Pacientes evaluados en menos de 30 días: 47% (estándar >75%). Tasa de hígados no implantados sin causa objetiva: 0,5% (estándar <1%). El 86% de los usuarios expresaron satisfacción (estándar >80%). Mortalidad en lista: 19% (estándar <15%). Mortalidad precoz con hígado funcionante: 1% (estándar <1%). Conclusiones: el PNTH del Uruguay cumple con la mayoría de los indicadores de calidad, presentando resultados en sobrevida por encima de los estándares internacionales.

Summary: Introduction: liver transplantation constitutes the first therapy chosen by patients with severe and irreversible liver conditions, when no effective alternative options are available. Measurement of quality indicators allow for the detection of problems that may be solved in order to optimize results. Objective: to present the results obtained in the National Program of Liver Transplantation in Uruguay, 10 years after its implementation and to compare them to international quality standards. Method: retrospective study of liver transplantations performed from July 14, 2009 through July 14, 2019. Results: N: 190 Liver transplantations (LT). Average age: 45 years old. Gender: 60% male. MELD average MELD (Model for End-stage Liver Disease) upon LT: 21. Main indications: cirrhosis he(59%) y hepatocarcinoma (21%). Post-surgery mortality: 7.4% and peri-operative mortality 2.1% (standards <10 and 1%). Re-transplantation rate: early 3.7% and late 4.2% (standards <5% and 8%). Reoperation rate: 13.1% (standard <10%) and of non-primary function: 2.6% (standard <2%). Survival: 86.6% per year, 81.8% after 3 years, 77.4% after 5 and 63.2% after 10 years (standards >80, 75, 70 and 60%). Patients assessed in less than 30 days: 47% (standard >75%). Non-implanted livers with no objective cause rate: 0.5% (standard <1%). 86% of users stated they were satisfied (standard >80%). Mortality in the waiting list: 19% (standard <15%). Early mortality with functioning liver: 1% (standard <1%). Conclusions: national Program of Liver Transplantation in Uruguay meets most quality indicators standards, evidencing survival results that are above international standards.

Resumo: Introdução: o transplante de fígado (TH) é o tratamento de escolha em pacientes com doenças hepáticas graves e irreversíveis, sem a opção de tratamentos alternativos eficazes. A medição de indicadores de qualidade permite detectar problemas que podem ser melhorados para otimizar os resultados. Objetivo: apresentar os resultados do Programa Nacional de Transplante de Fígado (PNTH) do Uruguai 10 anos após sua implantação e compará-los com os padrões internacionais de qualidade. Materiais e métodos: estudo retrospectivo do HT realizado de 14/07/2009 a 14/07/2019. Resultados: N: 190 TH. Idade média: 45 anos. Sexo: 60% homens. Escala MELD média no TH: 21. Principais indicações: cirrose (59%) e hepatocarcinoma (21%). Mortalidade pós-operatória: 7,4% e peri-operatória 2,1% (padrões <10 e 1%). Taxa de retransplante: 3,7% inicial e 4,2% tardio (padrão <5% e 8%). Taxa de reintervenção: 13,1% (padrão <10%) e não função primária: 2,6% (padrão <2%). Sobrevivência: 86,6% em 1 ano, 81,8% em 3, 77,4% em 5 e 63,2% em 10 anos (padrões> 80, 75, 70 e 60%). Pacientes avaliados em menos de 30 dias: 47% (padrão> 75%). Taxa de fígados não implantados sem causa objetiva: 0,5% (padrão <1%). 86% dos usuários expressaram satisfação (padrão> 80%). Mortalidade em lista de espera: 19% (padrão <15%). Mortalidade precoce com fígado funcionante: 1% (padrão <1%). Conclusões: o PNTH do Uruguai cumpre a maioria dos indicadores de qualidade, apresentando resultados de sobrevivência acima dos padrões internacionais.

Vigilancia activa de convulsiones febriles vinculadas a vacuna pentavalente en un hospital centinela en Uruguay / Active surveillance of febrile seizures associated to DPT vaccines in a sentinel hospital in Uruguay

Resumen Introducción: Las convulsiones febriles son eventos supuestamente atribuidos a la vacunación e inmunización (ESAVI) frecuentemente asociados a vacuna difteria - tétanos- pertussis a células completas. Objetivo: Analizar la asociación de convulsiones febriles con la administración de la vacuna pentavalente en niños bajo 2 años de edad asistidos en el Centro Hospitalario Pereira Rossell durante el año 2014. Material y Métodos: Estudio de series de casos auto-controlados. Se incluyeron niños procedentes de Montevideo con 2 a 24 meses de edad con diagnóstico de convulsión febril. Se estimó el riesgo relativo (RR) de los períodos de riesgo (0 a 3 días) y de lavado (4a 14 días), en comparación con el período de no riesgo (más de 14 días). Resultados: Se registraron 135 convulsiones febriles, que ocurrieron en 114 niños; 16 niños presentaron dos o más episodios. El total de eventos ocurridos en el período de riesgo fueron 7 (5,2%) y 8 (5,9%) en el período de lavado. El período de riesgo mostró un RR significativo de 4,14 (IC 95%: 1,73; 8,36). Conclusiones: Este trabajo permitió establecer una línea de base nacional sobre el riesgo de convulsiones febriles asociadas con la vacunación pentavalente al utilizar por primera vez en el país una metodología específica para tal fin.

Background: Febrile seizures are VAERS often associated with whole-cells Diphtheria-Pertussis-Tetanus vaccines. Aim: To analyze the association of febrile seizures with the administration of pentavalent vaccine in children under two-years-old assisted in the Centro Hospitalario Pereira Rossell (CHPR), in Montevideo during 2014. Methods: Self-controlled case series study. We included children from Montevideo from two to 24-month-old at the time of admission, with diagnosis of febrile seizure at the time of discharge. We estimated the relative risk in three time periods: 0 to 3 days (risk period), 4 to 14 days (wash-out) and more than 14 days after vaccination (no-risk). Results: We recorded 135 febrile seizures in 114 children, 16 of whom presented two or more events. The total number of events was 7 (5.2%) in risk periods and 8 (5.9%) in wash-out periods. The risk period showed a significantly increased risk (RR = 4.14, CI 95% = [1.73; 8.36]). Conclusions: This work allowed us to establish a national base line for the risk of febrile seizures associated with pentavalent vaccination, by using for the first time in the country a methodology specifically designed for this goal.