Bernal Leon

Servicio Nacional de Salud Animal, SENASA, Costa Rica, Diagnostico Veterinario, Department Member

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Address: Heredia, Heredia, Costa Rica

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Passive epidemiological surveillance in wildlife in Costa Rica identifies pathogens of zoonotic and conservation importance

PLOS ONE

Epidemiological surveillance systems for pathogens in wild species have been proposed as a preven... more Epidemiological surveillance systems for pathogens in wild species have been proposed as a preventive measure for epidemic events. These systems can minimize the detrimental effects of an outbreak, but most importantly, passive surveillance systems are the best adapted to countries with limited resources. Therefore, this research aimed to evaluate the technical and infrastructural feasibility of establishing this type of scheme in Costa Rica by implementing a pilot program targeting the detection of pathogens of zoonotic and conservation importance in wildlife. Between 2018 and 2020, 85 carcasses of free-ranging vertebrates were admitted for post-mortem and microbiology analysis. However, we encountered obstacles mainly related to the initial identification of cases and limited local logistics capacity. Nevertheless, this epidemiological surveillance scheme allowed us to estimate the general state of health of the country’s wildlife by establishing the causes of death according to p...

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File S3 from Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

Beast xml file to conduct the continuous phylogeographic analysis of the L1a and L2 viral lineage... more

Figure S1 from Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

Spatiotemporal distribution of vampire bat rabies outbreaks in Costa Rica (1985-2018).

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File S5 from Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

R script for spatiotemporal analyses of viral invasions and extinctions

File S4 from Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

Metadata for spatiotemporal analyses

File S2 from Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

Beast xml file to conduct the discrete phylogeographic analysis of the international dataset

File S1 from Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

Marginal likelihood and Bayes factor comparisons of molecular clock and spatiotemporal diffusion ... more

Factores de riesgo para las infecciones causadas por Ureaplasma diversum en vacas de un ambiente tropical

Revista De Biologia Tropical, 1995

A case-control study, detennined the influence of breed, age and number of deliveries as risk fac... more A case-control study, detennined the influence of breed, age and number of deliveries as risk factors for Ureaplasma genital infections in Costa Rica dairy cattle. The animals with none or one delivery had a risk of infection 2.99 times higher than those with several parturition, regardless of breed. The risk was 1.95 times higher in Jersey than in Holstein, and decreased progressively until three deliveries. In cows with four deliveries there was a significant in crease in the amount of animals infected and also a significant difference in the rate of infection between Holstein (27%) and Jersey (64%). Ureaplasma isolation was rare in cows with more than six deliveries.

Determinación de la presencia /ausencia del Pequeño Escarabajo de la Colmena (Aethina tumida Murray) en las explotaciones Apícolas Apis mellifera scutellata de Costa Rica

A study was conducted to determine the presence/absence of the small hive beetle SHB Aethina tumi... more A study was conducted to determine the presence/absence of the small hive beetle SHB Aethina tumida in apiaries in Costa Rica. The aim of this study was to sample hives of Apis mellifera scutellata in the most vulnerable areas due to their proximity to the neighboring country to the north, while the sampling method in the rest of the country was random. Samples were taken between June and October 2014. A total of 637 samples were analyzed from apiaries from four provinces in Costa Rica (Alajuela, San Jose, Puntarenas, and Guanacaste). No SHB was detected in any of these samples. These results are discussed.

Supplementary material from "Phylodynamics reveals extinction–recolonization dynamics underpin apparently endemic vampire bat rabies in Costa Rica

Variation in disease incidence in wildlife is often assumed to reflect environmental or demograph... more Variation in disease incidence in wildlife is often assumed to reflect environmental or demographic changes acting on an endemic pathogen. However, apparent endemicity might instead arise from spatial processes that are challenging to identify from traditional data sources including time series and field studies. Here, we analysed longitudinal sequence data collected from rabies virus outbreaks over 14 years in Costa Rica, a Central American country that has recorded continuous vampire bat-transmitted rabies outbreaks in humans and livestock since 1985. We identified five phylogenetically distinct lineages which shared most recent common ancestors with viruses from North and South America. Bayesian phylogeographic reconstructions supported bidirectional viral dispersals involving countries to the north and south of Costa Rica at different time points. Within Costa Rica, viruses showed little contemporaneous spatial overlap and no lineage was detected across all years of surveillance. Statistical models suggested that lineage disappearances were more likely to be explained by viral extinctions than undetected viral circulation. Our results highlight the importance of international viral dispersal for shaping the burden of rabies in Costa Rica, suggest a Central American corridor of rabies virus invasions between continents and show that apparent disease endemicity may arise through recurrent pathogen extinctions and reinvasions which can be readily detected in relatively small datasets by joining phylodynamic and modelling approaches.

Aislamiento de la bacteria ureaplasma sp en el tracto reproductivo de vacas lecheras de costa rica

Revista De Biologia Tropical, 1994

Se informa del primer aislamiento d e Urea plasma a partir del tracto reproductivo de vacas de Co... more Se informa del primer aislamiento d e Urea plasma a partir del tracto reproductivo de vacas de Costa Rica. Entre los 204 animales estudiados, provenientes de 11 fincas lecheras de la Meseta Central, el porcentaje de infeccion vario entre O y 71 %. El aislamiento de Ureaplasma sp. fue mas frecuente a partir de la region vulvo-vestibular (38.7%) que de la cervical (23%). Ureaplasma se correlaciono con la presencia de sintomas clinicos de vulvitis granular.

Diversidad genética entre subpoblaciones raciales bovinas de Costa Rica

Agronomía Costarricense, 2015

El objetivo del estudio fue cuantificar la diversidad genética entre 16 subpoblaciones raciales b... more El objetivo del estudio fue cuantificar la diversidad genética entre 16 subpoblaciones raciales bovinas de Costa Rica, con base en 1412 muestras de ADN bovino de todo el país, evaluadas mediante 18 marcadores microsatélites. El número promedio de alelos (Na) por locus dentro de raza fue de 10,3, que varían entre 8 (Holstein×Jersey) y 13 (Criolla para doble propósito). El número promedio de alelos efectivo (Ne) fue de 5,04, con cambios entre 4,18 (Jersey) y 5,64 (Bos taurus×Bos indicus). La heterocigosidad observada promedio fue de 0,77, variando entre 0,73 (Jersey) y 0,81 (Bos taurus×Bos indicus). La heterocigosidad esperada (He) promedio fue de 0,78, que oscilan entre 0,74 (Jersey y Holstein×Jersey) y 0,81 (Bos taurus×Bos indicus, Criolla para doble propósito y Cruces para doble propósito). El contenido de información polimórfica (PIC) fue de 0,76, con variaciones entre 0,71 (Jersey y Holstein×Jersey) y 0,79 (Criollas para doble propósito y Cruces para doble propósito). El FIS prom...

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First Complete Coding Sequence of a Venezuelan Equine Encephalitis Virus Strain Isolated from an Equine Encephalitis Case in Costa Rica

Microbiology Resource Announcements, 2019

The first complete coding sequence of the Venezuelan equine encephalitis virus IE, isolated from ... more

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Rabies in Costa Rica: Documentation of the Surveillance Program and the Endemic Situation from 1985 to 2014

Vector-Borne and Zoonotic Diseases, 2016

This is the first comprehensive epidemiological analysis of rabies in Costa Rica. We characterize... more This is the first comprehensive epidemiological analysis of rabies in Costa Rica. We characterized the occurrence of the disease and demonstrated its endemic nature in this country. In Costa Rica, as in other countries in Latin America, hematophagous vampire bats are the primary wildlife vectors transmitting the rabies virus to cattle herds. Between 1985 and 2014, a total of 78 outbreaks of bovine rabies was reported in Costa Rica, with documented cases of 723 dead cattle. Of cattle outbreaks, 82% occurred between 0 and 500 meters above sea level, and seasonality could be demonstrated on the Pacific side of the country, with significantly more outbreaks occurring during the wet season. A total of 1588 animal samples, or an average of 55 samples per year, was received by the veterinary authority (SENASA) for rabies diagnostic testing at this time. Of all samples tested, 9% (143/1588) were positive. Of these, 85.6% (125/1588) were from cattle; four dogs (0.3% [4/1588]) were diagnosed with rabies in this 30-year period. Simultaneously, an extremely low number (n = 3) of autochthonous rabies cases were reported among human patients, all of which were fatal. However, given the virus' zoonotic characteristics and predominantly fatal outcome among both cattle and humans, it is extremely important for healthcare practitioners and veterinarians to be aware of the importance of adequate wound hygiene and postexpositional rabies prophylaxis when dealing with both wild and domestic animal bites.

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02 León Chaves Koster Jenkins-Moore Carrill o Méndez

Diversidad genética en bovinos de ocho regiones en Costa Rica

Agronomía Mesoamericana, 2015

Diversidad genética en bovinos de ocho regiones en Costa Rica. El objetivo del presente estudio f... more Diversidad genética en bovinos de ocho regiones en Costa Rica. El objetivo del presente estudio fue explorar el grado de diversidad genética interregional presente en el ganado bovino de Costa Rica. Se colectaron 1498 muestras de ADN (año 2013) procedentes de ocho diferentes regiones del país. Se calcularon las frecuencias alélicas y los principales parámetros genéticos poblacionales para dieciocho marcadores microsatélite. Se realizó además un análisis de varianza molecular y se calcularon las distancias genéticas entre bovinos de diferentes regiones. A nivel nacional se observó un alto grado de diversidad, con un número promedio de 14,6±1,01 alelos observados y 5,6+0,37 alelos efectivos por marcador. La heterocigosis observada (Ho) fue 0,76±0,01 y la esperada (He) 0,81±0,01. El contenido de información polimórfica (CIP) fue de 0,79±0,06 y el índice de consanguinidad (F IS) fue de 0,06±0,004. A nivel de regiones, la Ho varió desde 0,73±0,02 en la región Central Sur hasta 0,78±0,01 en la región Huetar Norte. El dendrograma mostró tres agrupaciones claramente diferenciadas, con las regiones Central Metropolitana y Central Occidental en un grupo; Huetar Caribe, Central Sur, Pacífico Central y Chorotega en un segundo grupo; y Huetar Norte y Brunca en un tercer grupo intermedio. Los estimados de diferenciación genética R ST fueron significativos entre regiones de distintos grupos y no significativos entre regiones de un mismo grupo. Las diferencias genéticas entre regiones se relacionaron con la proliferación diferenciada de tipos raciales en función de su adaptabilidad a las condiciones agroecológicas y a los sistemas de producción imperantes en cada región.

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[Isolation of the bacteria Ureaplasma sp. in the reproductive tract of milking cows in Costa Rica]

Revista de biología tropical

This is the first report of Ureaplasma sp. from the reproductive tract of Costa Rican cows. Among... more This is the first report of Ureaplasma sp. from the reproductive tract of Costa Rican cows. Among 204 animals sampled from 11 dairy farms in the country's Central Plateau, the infection rate was 0-71%. Isolation was more frequent in vulvo-vestibular (38.7%) than in cervical swabs (23%). Ureaplasma was correlated with clinical granular vulvitis symptoms.

Development of a Lepto-IgM EIACR test to diagnose leptospirosis disease in Costa Rican patient samples

Investigación clínica, 2007

Leptospirosis is an endemic disease throughout Costa Rica, which could be misdiagnosed because ma... more Leptospirosis is an endemic disease throughout Costa Rica, which could be misdiagnosed because manifestations of this febrile disease may vary from mild flu-like symptoms to severe illness involving vital organs such as liver and lungs. Therefore an early specific diagnosis is important to ensure a favorable clinical outcome. The purpose of this study was to develop a Leptospira sp. anti-IgM EIA (Lepto-IgM EIACR) test and to compare it using Lepto-Dipstick IgM (Lepto-DS IgM) and PanBio-EIA IgM with the Microscopy Agglutination test (MAT) as a reference assay. Sera from 736 healthy blood donors were used as negative controls to calculate specificity (97.1%), Confidence Interval 95 (CI (96-98). Cross reactivity was evaluated in 268 patient samples with 6 different diseases. Dengue and measles had the highest cross reactivity (16%) while rubella showed the lowest (3%). To determine the sensitivity of the Lepto- IgM EIACR, 33 samples positive by MAT of 96 paired samples from patients wi...

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Study of antiretroviral mutants in HIV patients with treatment failures and the effect of risk factors in the virological failures

Revista do Instituto de Medicina Tropical de São Paulo, 2005

INTRODUCTION: Information about HIV phenotypes of resistant to available ART and the influence of... more INTRODUCTION: Information about HIV phenotypes of resistant to available ART and the influence of different risk factors on virological failures (VF) in Costa Rican HIV positive patients prior or during HAART is unknown. MATERIALS AND METHODS: Eighty nine samples, 72 VF and 17 basal (before treatment) were analyzed by examining resistant mutants in reverse transcriptase (RT) and protease (PT) regions using Trugene or LIPA genotyping kits. Sixty eight control patients were selected and relevant information was collected in a questionnaire. RESULTS: Poor adherence, presence of resistant mutations and number of treatment's changes were the only significant factors found (p = 0.006, 0.04 and 0.01 respectively). From 66 sequenced samples, 78%, 50% and 50% showed resistance to NRTI (nucleoside reverse transcriptase inhibitors), NNRT (non-nucleoside reverse transcriptase inhibitors) and PI (protease inhibitors), respectively. The most frequent mutations were M41L, M184V, and T215FY in ...

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Análisis molecular de una cepa de virus de Newcastle de origen vacunal aislada a partir de un hisopado cloacal de aves sanas en Costa Rica-Molecular …

REDVET, 2009

Análisis molecular de una cepa de virus de Newcastle de origen vacunal aislada a partir de un his... more

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