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Rickettsia parkeri belongs to the spotted fever group (SFG) of the Rickettsia genus. This bacterium causes mild rickettsiosis in humans and is mainly transmitted by Amblyomma ticks. Its medical importance is emerging in the Americas, including Mexico. Synanthropic rodents and domiciled dogs participate as accidental hosts in epidemiological cycles of Rickettsia of the SFG. The aim is to report the presence of R. parkeri in synanthropic rodents and domiciled dogs from a rural community of Yucatán, Mexico. Rodents were captured, and plasma samples were taken from dogs in 48 households from Ucú, Yucatán, Mexico. A spleen sample (rodents) and plasma (dogs) were used in the propagation of Rickettsia on Vero cells. These infected cells were used in the extraction of genomic DNA. Rickettsia DNA was identified using a semi-nested PCR (snPCR); some products were sent for sequencing. The recovered sequences were analysed with bioinformatics programs, and a phylogenetic tree was built to determine the Rickettsia species. One hundred animals were sampled: 36 synanthropic rodents and 64 dogs. The snPCR evidenced the presence of Rickettsia DNA in 10 rodents (10/36, 27.8%) and 18 dogs (18/64, 28.1%), which represents a global frequency of 28% (28/100) in this study. The bioinformatics analysis yielded homology to R. parkeri and was demonstrated in the phylogenetic tree. The first evidence of the presence of R. parkeri in synanthropic rodents (Mus musculus) from Mexico is presented; likewise, the participation of domestic dogs in the transmission cycle of this bacterium with potential importance in public health is confirmed.

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The aim is to describe the Typhus group (TG) Rickettsia infection in dogs and to identify factors associated with this infection. We collected blood samples and gathered exposure and clinical data of 142 dogs from a rural community of Yucatan. The Rickettsia group was determined by semi-nested PCR. Generalized linear models with binomial error distribution were used to model the associated factors from the dog sample for risk ratio (RR) estimation. Thirty-four dogs (23.9%) showed molecular evidence of TG Rickettsia DNA. The multivariate model showed that mixed-breed dogs (RR = 0.06) and dogs that had received antiparasitic treatment (RR = 0.049) had a lower risk of getting infected, taking as reference the purebred group and the non-treated dogs, respectively. Looking at variable interactions, adult dogs without outdoor activities had a lower infection risk than puppies (RR = 0.26). Among dogs with antiparasitic treatment, females had a higher infection risk than male dogs (RR = 26.2). The results showed enzootic TG Rickettsia circulation in dogs of a rural community. The factors outdoor activities, age and previous antiparasitic treatment, as well as the clinical variables signs of hemorrhages and epistaxis, were associated with a less chance of natural infection in the studied dogs. Prevention and control of the enzootic transmission risk of TG Rickettsia should help to reduce the potential zoonotic transmission of this pathogen.

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Infections with viruses of the Flavivirus genus were explored in 22 bats (Artibeus jamaicensis) from Merida, Yucatan, Mexico. The detection of the viral genus was performed by RT-PCR, and infections with dengue (DENV 1-4), West Nile (WNV) and Zika (ZIKV) viruses were subsequently explored. Sequences from positive products were analysed using the BLAST algorithm to determine identity. In 7 (31.8%) and 2 (9.1%) bats, WNV and ZIKV were identified, respectively. The bioinformatic analysis showed 98%-100% coverage and identity for both viruses. Molecular evidence of WNV and ZIKV natural infection in bats from Yucatan, Mexico, is presented.

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Cases of acute haemorrhagic conjunctivitis (AHC) caused by a coxsackie virus A24 variant (CV-A24v) in Mexico have been reported since 1987; however, no molecular data on the causative strains have been available. Here, we report the identification of the etiological agent responsible for the most recent AHC outbreak in southeastern Mexico (at the end of 2017) as well as the complete genome sequences of seven isolates, using next-generation sequencing (NGS). Phylogenomic analysis of the CV-A24v sequences reported here showed similarity to contemporary strains causing AHC outbreaks in French Guiana and Uganda, forming a novel clade related to genotype IV. Moreover, a specific mutational pattern in the non-structural proteins was identified in the 2017 isolates. This is the first report of genetic characterization of CV-A24v isolates obtained in Mexico.

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Introduction: Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which is endemic in México and considered a public and veterinary health problem. Rodents are the most relevant reservoirs of Leptospira spp. because the bacteria establish and reproduce in its renal tissue and are excreted through the urine. Objective: To identify the presence of Leptospira spp. in renal tissue from rodents captured in Yucatán, México. Materials and methods: Synanthropic and wild rodents were captured in the rural municipality of Cenotillo, Yucatán, México. We collected one kidney from each rodent and extracted the total DNA. The identification of Leptospira spp. was done by detecting two fragments of the 16S rRNA gene using end-point polymerase chain reaction (PCR). We sequenced and analyzed positive products using alignment tools. Results: A total of 92 rodents belonging to seven different species were captured. The PCR yielded a global positivity of 5.4% (5/92). The alignment analysis of the sequenced products demonstrated a 100% of coverage and identity with Leptospira interrogans. This is the first molecular evidence of Leptospira spp. circulation in Heteromys gaumeri captured in Yucatán, México. Conclusion: Our results evidenced that rodents of Yucatán are reservoirs of Leptospira spp. and participate in the infection cycle of leptospirosis in the region.

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Introducción. La leptospirosis es una enfermedad zoonótica endémica en México, ocasionada por la bacteria del género Leptospira, la cual constituye un problema de salud pública y veterinaria. Los roedores son los reservorios más relevantes de Leptospira spp., debido a que la bacteria se establece y se reproduce en su tejido renal y es excretada por la orina. Objetivo. Identificar la presencia de Leptospira spp. en tejido renal de roedores capturados en Yucatán, México. Materiales y métodos. Se capturaron roedores sinantrópicos y silvestres en el municipio rural de Cenotillo, Yucatán, México. Se tomó un riñón de cada roedor y se extrajo el ADN total. La identificación de Leptospira spp. se hizo mediante la detección de dos fragmentos del gen 16S rRNA con una reacción en cadena de la polimerasa (PCR) de punto final. Los productos positivos se secuenciaron y se analizaron con herramientas de alineamiento. Resultados. Se capturaron 92 roedores pertenecientes a siete especies distintas. La PCR arrojó 5,4 % (5/92) de positividad global. El análisis del alineamiento de los aislamientos de los roedores infectados demostró 100 % de cobertura e identidad con la especie Leptospira interrogans. Esta es la primera evidencia molecular de la circulación de Leptospira spp. en Heteromys gaumeri capturados en Yucatán, México. Conclusión. Se evidenció que los roedores de Yucatán, México, son reservorios de Leptospira spp. y participan en el ciclo de infección de la leptospirosis en la región.

Introduction: Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which is endemic in México and considered a public and veterinary health problem. Rodents are the most relevant reservoirs of Leptospira spp. because the bacteria establish and reproduce in its renal tissue and are excreted through the urine. Objective: To identify the presence of Leptospira spp. in renal tissue from rodents captured in Yucatán, México. Materials and methods: Synanthropic and wild rodents were captured in the rural municipality of Cenotillo, Yucatán, México. We collected one kidney from each rodent and extracted the total DNA. The identification of Leptospira spp. was done by detecting two fragments of the 16S rRNA gene using end-point polymerase chain reaction (PCR). We sequenced and analyzed positive products using alignment tools. Results: A total of 92 rodents belonging to seven different species were captured. The PCR yielded a global positivity of 5.4% (5/92). The alignment analysis of the sequenced products demonstrated a 100% of coverage and identity with Leptospira interrogans. This is the first molecular evidence of Leptospira spp. circulation in Heteromys gaumeri captured in Yucatán, México. Conclusion: Our results evidenced that rodents of Yucatán are reservoirs of Leptospira spp. and participate in the infection cycle of leptospirosis in the region.

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Resumen Introducción La Investigación Participativa (IP), es una herramienta que puede abordarse para el análisis y mejoramiento de procesos socioculturales, medioambientales, y de salud pública. La participación de niños en edad escolar en la apropiación del conocimiento sobre la Enfermedad de Chagas (EC), puede romper el ciclo de transmisión. La EC es un problema de salud pública que afecta principalmente a comunidades rurales endémicas de países en desarrollo. Objetivo Desarrollar una estrategia para la adquisición y transferencia de nuevos conocimientos en niños y niñas, debido a la falta de información acerca del ciclo de transmisión de la EC . Material y Métodos Estudio socioambiental, realizado con un grupo de 48 niños y niñas de una comunidad en pobreza extrema en Yucatán, México. Mediante herramientas de IP y con el apoyo de las familias, autoridades ejidales y escolares, se impartieron talleres educativos a niños y niñas de educación básica para conocer el ciclo de transmisión de la EC y ayudar a prevenirla, debido a la abundancia del vector en el área de estudio. Se implementó un programa denominado "Pequeños Investigadores", para iniciar procesos de apropiación y socialización del conocimiento en la comunidad. Resultados El nuevo conocimiento adquirido por el grupo de niñas y niños fue aprovechado y compartido a sus familias, compañeros de escuela, y círculos sociales, fomentando la prevención de la enfermedad. Fueron recolectados 182 triatomas a nivel domiciliar y peri domiciliar. Conclusiones Los nuevos conocimientos, actitudes y prácticas adquiridos por los niños y las niñas bajo esquemas de participación, resulta benéfico para la prevención de la EC. Se recomienda al sector oficial la participación en la promoción de la salud en niños y niñas bajo el esquema del presente estudio en países en desarrollo.

Abstract Introduction Participatory Research (PR) is a tool that can be approached for the analysis of sociocultural, environmental, and public health processes. The participation of school-age childrens in the appropriation of knowledge for the prevention of Chagas' Disease (CD) can break the cycle of transmission. CD is a public health problem that mainly affects rural endemic communities of developing countries. Objective To develop a strategy for the acquisition and transfer of new knowledge in childs, due to the lack of information about the transmission cycle of the EC. Materials and Methods A cross-sectional study was carried out with a group of 48 childrens from a community in extreme poverty in Yucatan, Mexico. Through PR tools and with the support of parents, ejidal and school authorities, educational workshops were given to children of the basic education to know the cycle of transmission, and to prevent CD due to the abundance of the vector in the study area. A program called "Small Investigators" was implemented to initiate processes of appropriation and socialization of knowledge in the community. Results The new knowledge acquired by the group of children was used and disseminated to their families, partners, and social circles, promoting the prevention of the disease. 182 triatomas were collected at home and peri domicile. Conclusions The new knowledge, attitudes and practices acquired by children under participation schemes is beneficial for the prevention of the Chagas Disease. The official sector is recommended to design the promotion health programs in children under the scheme of the present study in developing countries.

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The majority of the Yucatán State, México, presents subtropical climate that is suitable for many species of mosquitoes that are known to be vectors of diseases, including those from the genera Aedes and Culex. The objective of this study is to identify the geographic distribution of five species from these two genera and estimate the human population at risk of coming in contact with them. We compiled distributional data for Aedes aegypti (L.), Aedes (Howardina) cozumelensis (Diaz Najera), Culex coronator Dyar and Knab, Culex quinquefasciatus Say, and Culex thriambus Dyar from several entomological studies in Yucatán between March 2010 and September 2014. Based on these data, we constructed ecological niche models to predict the spatial distribution of each species using the MaxEnt algorithm. Our models identified areas with suitable environments for Ae. aegypti in most of Yucatán. A similar percentage of urban (97.1%) and rural (96.5%) populations were contained in areas of highest suitability for Ae. aegypti, and no spatial pattern was found (Moran's I = 0.33, P = 0.38); however, we found an association of abundance of immature forms of this species with annual mean temperature (r = 0.19, P ≤ 0.001) and annual precipitation (r = 0.21, P ≤ 0.001). Aedes cozumelensis is also distributed in most areas of the Yucatán State; Cx. quinquefasciatus, Cx. coronator, and Cx. thriambus are restricted to the northwest. The information generated in this study can inform decision-making to address control measures in priority areas with presence of these vectors.

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Spirochete bacteria Leptospira spp. is the causative agent of leptospirosis, antropozoonotic endemic disease in many parts of the world, mainly in underdeveloped countries with high levels of poverty. Its incidence and prevalence rates are higher and important in human populations living in tropical and subtropical climates. Leptospira spp., is capable of infecting more than 160 species of domestic and wild mammals, including human beings, causing various and nonspecific clinical manifestations that make the diagnosis of the disease rarely accurate. In Mexico, the first reports of leptospirosis dating from 1920 and is now considered a matter of public and animal health, mainly for the economic losses it generates. The aim of this paper is to present a review in Spanish, containing the most important aspects in the epidemiology of leptospirosis, to serve as a starting point for students and researchers who are interested about this endemic disease in Mexico.

La bacteria espiroqueta Leptospira spp. es el agente causal de la leptospirosis, enfermedad antropozoonótica endémica en varias regiones del mundo, principalmente en países poco desarrollados y con altos niveles de pobreza. Sus tasas de incidencia y prevalencia son más altas e importantes en poblaciones humanas que habitan en climas tropicales y subtropicales. Leptospira spp., además de afectar al ser humano, es capaz de infectar a más de 160 especies de mamíferos domésticos y silvestres, ocasionando diversas e inespecíficas manifestaciones clínicas que evitan que el diagnóstico de la enfermedad sea certero. En México, los primeros reportes de leptospirosis datan de 1920 y actualmente se le considera un problema de salud pública y pecuaria, principalmente por las pérdidas económicas que genera. El objetivo de este trabajo es presentar una revisión en idioma español, que contenga los aspectos más relevantes en la epidemiología de la leptospirosis, para que sirva de punto de partida a estudiantes e investigadores que tienen interés sobre esta enfermedad endémica en México.

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OBJECTIVE: To report the renal histological lesions in synanthropic rodents, Mus musculus and Rattus rattus, naturally infected with Leptospira spp., captured in a rural community in Yucatan, Mexico. METHODS: Kidney samples of synanthropic rodents were collected from a rural community in Yucatan, Mexico. Polymerase chain reaction was used to detect Leptospira spp. infection. Tissue kidney was fixed in 10% buffered formalin, processed according to the usual techniques for paraffin inclusion, cut and stained with hematoxylin and eosin, and examined using a conventional electronic microscope. RESULTS: A total of 187 rodents were captured. Nine individuals (4.8%) were positive for Leptospira spp. in the molecular analysis. All renal lesions observed in the histopathological study had been reported previously for Leptospira spp. infection. CONCLUSIONS: The histopathological lesions are present in the kidneys, plus the results of the polymerase chain reaction confirm that these rodents are true carriers of Leptospira spp.

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Coinfection produced by dengue virus (DENV) and hepatitis C virus (HCV) is a serious problem of public health in Mexico, as they both circulate in tropical zones and may lead to masking or complicating symptoms. In this research, we detected active coinfected patients by HCV residing in the endemic city of Mérida, Yucatán, Mexico, with positive diagnosis to dengue during the acute phase. We performed a retrospective analysis of 240 serum samples from dengue patients. The IgM-ELISA serological test was used for dengue diagnosis, as well as viral isolation to confirm infection. DENV and HCV were detected by RT-PCR. Thus, 31 (12.9%) samples showed DENV-HCV coinfection, but interestingly the highest frequency of coinfection cases was found in male patients presenting hemorrhagic dengue in 19/31 (61.29%), with a predominance of 12 : 7 in males. Firstly, coinfection of DENV-HCV in Mérida, Mexico, was detected in young dengue patients, between 11 and 20 years old (38.7%), followed by those between 21 and 30 years old (32%); only 16.13% were between 0 and 10 years of age. Diagnosis of HCV infection in patients with dengue is highly recommended in order to establish potential risk in clinical manifestations as well as dictate patients' special care.

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Introduction: TLR´s play a role in host defense in HIV infection recognizing the viral DNA or RNA. Their activation induces a signaling pathway that includes the proteins MyD88, IRAK4, TRAF6 and the transcription factor NF-kBp65. Objective: To determine the expression of TLR7, TLR8 and TLR9, and activation of its signaling pathway in monocytes from patients infected with HIV. Methods. Expression of TLR7, TLR8 and TLR9 was determined in monocytes from HIV-infected patients (n= 13) and control subjects (n= 13), which were activated with specific ligands. The expression of MyD88 and NF-kBp65 were determined by flow cytometry; IRAK4 and TRAF6 were studied by immunoblotting. Results: No statistical difference was found in the expression of TLR7, 8 and 9 in monocytes from patients compared to controls, but we observed the non-significant increased expression of TLR9 in patients. The activation showed no significant difference in the expression of MyD88 and NF-kBp65 in patients when compared to controls, but were decreased in stimulated cells over non-stimulated cells. IRAK4 and TRAF6 were not detected. Conclusions: No statistical difference was observed in the expression of intracellular TLRs, MyD88 and NFkBp65 in monocytes from patients compared to controls. This was probably due to effective antiretroviral therapy being received at the time of study entry. Additional studies are needed under controlled conditions that include infected patients with and without ARVT, responders and non-responders, and work with different cell populations.

Introducción: En la infección por VIH los TLR juega un papel en la defensa del huésped al reconocer el ADN o ARN viral. Su activación induce la vía de señalización que incluye las proteínas MyD88, IRAK4, TRAF6 y el factor de transcripción NF-kBp65. Objetivo: Determinar la expresión del TLR7, TLR8 y TLR9, y activación de su vía de señalización en monocitos de pacientes infectados con VIH. Métodos: Se determinó la expresión de TLR7, TLR8 y TLR9 en monocitos de pacientes infectados con VIH (n =13) y sujetos control (n =13), se activaron con ligandos específicos y se determinó la expresión de MyD88 y NF-kBp65 por citometría de flujo. IRAK4 y TRAF6 fueron estudiadas por inmunoelectrotransferencia. Resultados: No se observó diferencia estadística en la expresión de TLR7, 8 y 9 en los monocitos de pacientes con respecto a los controles, pero observamos aumento no significante del TLR9 en los pacientes. La activación no mostró diferencia significativa en la expresión de MyD88 y NF-kBp65 en pacientes con respecto a los controles, pero se encontraron disminuidas en células estimuladas con respecto a las no estimuladas. IRAK4 y TRAF6 no se detectaron. Conclusiones: No se observó diferencia en la expresión de los TLR, ni en la expresión de MyD88 y NFkBp65, en monocitos de pacientes con respecto a los controles probablemente debido a la terapia antirretroviral recibida al momento del estudio. Se sugieren estudios con pacientes con y sin TARV, respondedores y no respondedores, y trabajar con diferentes poblaciones celulares.

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INTRODUCTION: TLR´s play a role in host defense in HIV infection recognizing the viral DNA or RNA. Their activation induces a signaling pathway that includes the proteins MyD88, IRAK4, TRAF6 and the transcription factor NF-kBp65. OBJECTIVE: To determine the expression of TLR7, TLR8 and TLR9, and activation of its signaling pathway in monocytes from patients infected with HIV. Methods. Expression of TLR7, TLR8 and TLR9 was determined in monocytes from HIV-infected patients (n= 13) and control subjects (n= 13), which were activated with specific ligands. The expression of MyD88 and NF-kBp65 were determined by flow cytometry; IRAK4 and TRAF6 were studied by immunoblotting. RESULTS: No statistical difference was found in the expression of TLR7, 8 and 9 in monocytes from patients compared to controls, but we observed the non-significant increased expression of TLR9 in patients. The activation showed no significant difference in the expression of MyD88 and NF-kBp65 in patients when compared to controls, but were decreased in stimulated cells over non-stimulated cells. IRAK4 and TRAF6 were not detected. CONCLUSIONS: No statistical difference was observed in the expression of intracellular TLRs, MyD88 and NFkBp65 in monocytes from patients compared to controls. This was probably due to effective antiretroviral therapy being received at the time of study entry. Additional studies are needed under controlled conditions that include infected patients with and without ARVT, responders and non-responders, and work with different cell populations.

INTRODUCCIÓN: En la infección por VIH los TLR juega un papel en la defensa del huésped al reconocer el ADN o ARN viral. Su activación induce la vía de señalización que incluye las proteínas MyD88, IRAK4, TRAF6 y el factor de transcripción NF-kBp65. OBJETIVO: Determinar la expresión del TLR7, TLR8 y TLR9, y activación de su vía de señalización en monocitos de pacientes infectados con VIH. MÉTODOS: Se determinó la expresión de TLR7, TLR8 y TLR9 en monocitos de pacientes infectados con VIH (n= 13) y sujetos control (n= 13), se activaron con ligandos específicos y se determinó la expresión de MyD88 y NF-kBp65 por citometría de flujo. IRAK4 y TRAF6 fueron estudiadas por inmunoelectrotransferencia. RESULTADOS: No se observó diferencia estadística en la expresión de TLR7, 8 y 9 en los monocitos de pacientes con respecto a los controles, pero observamos aumento no significante del TLR9 en los pacientes. La activación no mostró diferencia significativa en la expresión de MyD88 y NF-kBp65 en pacientes con respecto a los controles, pero se encontraron disminuidas en células estimuladas con respecto a las no estimuladas. IRAK4 y TRAF6 no se detectaron. CONCLUSIONES: No se observó diferencia en la expresión de los TLR, ni en la expresión de MyD88 y NFkBp65, en monocitos de pacientes con respecto a los controles probablemente debido a la terapia antirretroviral recibida al momento del estudio. Se sugieren estudios con pacientes con y sin TARV, respondedores y no respondedores, y trabajar con diferentes poblaciones celulares.

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OBJECTIVE: To determine the prevalence of West Nile Virus (WNV) infection in animals, mosquitoes and employees from two zoos of Tabasco state, Mexico. MATERIAL AND METHODS: WNV antibodies were detected by blocking ELISA in serum samples from animals. Viral RNA was detected by RT-PCR from mosquitoes and serum samples from employees at "Yum-Ká" zoo. RESULTS: Seroprevalence in birds was 25.65% (19/74) and 85% (6/7) in reptiles from "La Venta" zoo. Thirty-one percent of birds (50/160) and 34.48% mammals (16/29) at the "Yum-Ká" zoo, were seropositive. All human serum samples from Yum-ká zoo were negative by RT-PCR. A pool of mosquitoes (Culex quinquefasciatus) was positive for WNV. CONCLUSIONS: The presence of WNV antibodies in animals from both zoos and the detection of viral genome in mosquitoes demonstrate the presence of WNV in this region and indicates a potential risk of infection in animals and humans.

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OBJETIVO: Determinar la prevalencia de infección por el virus del Nilo Occidental (VNO) en animales, mosquitos y personal que labora en dos zoológicos del estado de Tabasco, en México. MATERIAL Y MÉTODOS: Con la utilización de ELISA de bloqueo se detectaron anticuerpos en sueros de animales: se buscó un fragmento del genoma del VNO por RT-PCR en el suero de animales, empleados y mosquitos. RESULTADOS: En el zoológico "La Venta" se encontró una seroprevalencia de 25.67 por ciento (19/74) en aves y de 85.71 por ciento (6/7) en reptiles. En el zoológico "Yum-Ká", 31.25 por ciento (50/160) de las aves y 34.48 por ciento (16/29,) de los mamíferos, tuvieron anticuerpos contra el VNO. En un grupo de mosquitos (Culex quinquefasciatus) se detectó el genoma del virus. CONCLUSIONES: La detección de anticuerpos contra el VNO en animales de ambos zoológicos y del genoma viral en mosquitos demuestra la presencia del virus, lo cual representa un riesgo potencial de infección para animales y humanos.

OBJECTIVE: To determine the prevalence of West Nile Virus (WNV) infection in animals, mosquitoes and employees from two zoos of Tabasco state, Mexico. MATERIAL AND METHODS: WNV antibodies were detected by blocking ELISA in serum samples from animals. Viral RNA was detected by RT-PCR from mosquitoes and serum samples from employees at "Yum-Ká" zoo. RESULTS: Seroprevalence in birds was 25.65 percent (19/74) and 85 percent (6/7) in reptiles from "La Venta" zoo. Thirty-one percent of birds (50/160) and 34.48 percent mammals (16/29) at the "Yum-Ká" zoo, were seropositive. All human serum samples from Yum-ká zoo were negative by RT-PCR. A pool of mosquitoes (Culex quinquefasciatus) was positive for WNV. CONCLUSIONS: The presence of WNV antibodies in animals from both zoos and the detection of viral genome in mosquitoes demonstrate the presence of WNV in this region and indicates a potential risk of infection in animals and humans.

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La enfermedad producida por el virus de la enfermedad de Borna (VEB) o Borna Disease Virus (BDV), conocida como una encefalitis fatal, se ha reportado en caballos y ovejas en Europa Central, desde hace más de dos siglos. Los animales infectados por el VEB muestran cambios en el comportamiento: ansiedad, agresividad, separación del rebaño e hiperactividad. Estos signos también pueden encontrarse en seres humanos, con trastornos psiquiátricos como: enfermedad bipolar, depresión, esquizofrenia o encefalitis idiopáticas. Estas manifestaciones en los animales infectados se deben principalmente, a la respuesta inmune contra las células infectadas del sistema nervioso central (SNC). Desde 1980 se ha demostrado evidencia serológica de infección por el VEB en humanos. Sin embargo, aún existe mucho por investigar en este tema. En numerosos estudios se ha intentado asociar la presencia de anticuerpos o de partículas virales con manifestaciones psiquiátricas. Debido a que los desórdenes psiquiátricos son un problema importante en salud pública, y a que la gran mayoría de los reportes científicos se han hecho en países desarrollados en donde la epidemiología de las enfermedades muestran un comportamiento muy distinto a la que se observa en países tropicales en vías de desarrollo, es necesario realizar análisis rigurosos para corroborar o refutar el efecto de la infección por el VEB en algunas enfermedades mentales.

The disease caused by Borna Disease Virus (BDV), known as fatal encephalitis, has been diagnosed in horses and sheeps en Central Europe for over a century. Infected animals show changes in the behaviour such as anxiety, separation of the herd, and hyperactivity. This signs can be found in humans with psychiatric syndromes like bipolar disease, depression, schizophrenia, or idiopathic diseases. The manifestations in infected animals are due to the immune response against the infected cells in the central nervous system. Since 1980, serological evidence of BDV infection has been reported in humans and many suggested an association of specific antibodies or viral particles with psychiatric manifestations.Because most of the studies have been done in developed countries where epidemiological manifestations are different to those observed in tropical developing countries, it is necessary to do rigorous analysis to corroborate or refute the effect of BDV in some mental diseases.

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The prevalence and type diversity of human astroviruses (HAstV) in children with symptomatic and asymptomatic infections were determined in five localities of Mexico. HAstV were detected in 4.6 (24 of 522) and 2.6% (11 of 428) of children with and without diarrhea, respectively. Genotyping of the detected strains showed that at least seven (types 1 to 4 and 6 to 8) of the eight known HAstV types circulated in Mexico between October 1994 and March 1995. HAstV types 1 and 3 were the most prevalent in children with diarrhea, although they were not found in all localities studied. HAstV type 8 was found in Mexico City, Monterrey, and Mérida; in the last it was as prevalent (40%) as type 1 viruses, indicating that this astrovirus type is more common than previously recognized. A correlation between the HAstV infecting type and the presence or absence of diarrheic symptoms was not observed. Enteric adenoviruses were also studied, and they were found to be present in 2.3 (12 of 522) and 1.4% (6 of 428) of symptomatic and asymptomatic children, respectively.

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Serum samples were obtained from 252 horses in the State of Yucatan, Mexico, from July to October 2002. Antibodies to West Nile virus were detected by epitope-blocking enzyme-linked immunosorbent assays in three (1.2%) horses and confirmed by plaque reduction neutralization test. We report the first West Nile virus activity in the State of Yucatan.

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