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Age-related seroprevalence study for St. Louis encephalitis in a population from Cordoba, Argentina
SPINSANTI, Lorena Ivana;Ré, Viviana Elizabeth;DíAZ, María Pilar;CONTIGIANI, Marta Silvia;
Revista do Instituto de Medicina Tropical de S?o Paulo , 2002, DOI: 10.1590/S0036-46652002000200001
Abstract: a serological screening was performed in 615 individuals aged 0-87 years, living in the city of cordoba, argentina to study the relationship between antibody prevalence for the sle virus and age. a 13.98% prevalence of neutralizing antibodies was obtained and its relation to age was significantly high (p = 0.045). the highest seroprevalence was noted on individuals over 60 years old (>20%), whereas no subject under 10 was seropositive for this virus. our results confirm that the agent is endemic in this area and neurological pathology studies should be performed on those individuals aged 60 since they represent the most susceptible group to sle virus.
Age-related seroprevalence study for St. Louis encephalitis in a population from Cordoba, Argentina  [cached]
SPINSANTI Lorena Ivana,Ré Viviana Elizabeth,DíAZ María Pilar,CONTIGIANI Marta Silvia
Revista do Instituto de Medicina Tropical de S?o Paulo , 2002,
Abstract: A serological screening was performed in 615 individuals aged 0-87 years, living in the city of Cordoba, Argentina to study the relationship between antibody prevalence for the SLE virus and age. A 13.98% prevalence of neutralizing antibodies was obtained and its relation to age was significantly high (p = 0.045). The highest seroprevalence was noted on individuals over 60 years old (>20%), whereas no subject under 10 was seropositive for this virus. Our results confirm that the agent is endemic in this area and neurological pathology studies should be performed on those individuals aged 60 since they represent the most susceptible group to SLE virus.
Comparison of Argentinean Saint Louis Encephalitis Virus Non-Epidemic and Epidemic Strain Infections in an Avian Model  [PDF]
Luis Adrián Diaz ,Nicole M. Nemeth,Richard A. Bowen,Walter R. Almiron,Marta S. Contigiani
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001177
Abstract: St. Louis encephalitis virus (SLEV, Flavivirus, Flaviviridae) is an emerging mosquito-borne pathogen in South America, with human SLEV encephalitis cases reported in Argentina and Brazil. Genotype III strains of SLEV were isolated from Culex quinquefasciatus mosquitoes in Cordoba, Argentina in 2005, during the largest SLEV outbreak ever reported in South America. The present study tested the hypothesis that the recent, epidemic SLEV strain exhibits greater virulence in birds as compared with a non-epidemic genotype III strain isolated from mosquitoes in Santa Fe Province 27 years earlier. The observed differences in infection parameters between adult House sparrows (Passer domesticus) that were needle-inoculated with either the epidemic or historic SLEV strain were not statistically significant. However, only the House sparrows that were infected with the epidemic strain achieved infectious-level viremia titers sufficient to infect Cx. spp. mosquitoes vectors. Furthermore, the vertebrate reservoir competence index values indicated an approximately 3-fold increase in amplification potential of House sparrows infected with the epidemic strain when pre-existing flavivirus-reactive antibodies were present, suggesting the possibility that antibody-dependent enhancement may increase the risk of avian-amplified transmission of SLEV in South America.
Encefalitis por virus San Luis en la Ciudad de Buenos Aires durante el brote de dengue 2009 Saint Louis encephalitis virus in Buenos Aires city during the outbreak of dengue in 2009
Horacio López,Jorge Neira,María Alejandra Morales,Cintia Fabbri
Medicina (Buenos Aires) , 2011,
Abstract: Se presenta un paciente de 80 a os de edad, residente en la Ciudad de Buenos Aires, con diagnóstico serológico para el virus de la encefalitis de San Luis (SLE) durante el brote de dengue ocurrido entre enero y mayo de 2009. Presentaba leucemia linfoide crónica en tratamiento con clorambucilo, cáncer de próstata tratado con hormonoterapia y radioterapia, e imágenes óseas compatibles con metástasis. El estudio del líquido cefalorraquídeo demostró pleocitosis con predominio de mononucleares y proteinorraquia elevada. El resultado de los cultivos para bacterias, hongos y micobacterias, así como el PCR en LCR para herpes virus, HSV, CMV y EBV, fue negativo. Se detectaron anticuerpos IgM para virus SLE tanto en LCR como en muestra de suero, con seroconversión IgG por neutralización en cultivos celulares y resultados negativos para los demás Flavivirus con circulación en Argentina. Se revisan evidencias sobre la presencia de virus de San Luis en nuestro país, y se se ala la importancia de la confirmación diagnóstica y el estudio de otros Flavivirus en casos sospechosos de dengue con presentación grave o atípica. Este trabajo remarca la necesidad de fortalecer tanto la vigilancia epidemiológica del virus SLE, como el control vectorial para prevenir las diferentes infecciones transmitidas por mosquitos y conocer su efecto en Salud Pública en la Argentina. We report the case of a male, 80-year-old resident in the City of Buenos Aires, with a diagnosis of St. Louis encephalitis (SLE) during a countrywide dengue outbreak, from January to May 2009. The patient had a chronic lymphocytic leukemia treated with chlorambucil, prostate cancer (hormone therapy and radiotherapy) and images consistent with bone metastases. Cerebrospinal fluid examination showed pleocytosis with a predominance of mononuclear cells and high protein concentration. Bacteria, fungi and mycobacteria cultures, as well as the PCR for herpes virus, HSV, CMV and EBV, were negative. We confirmed the diagnosis of SLE by detection of IgM antibodies in both CSF and serum sample with IgG seroconversion by neutralization in cell cultures and negative results for other flaviviruses with known circulation in Argentina. We review the evidence for the presence of the St. Louis virus in our country and point to the importance of the diagnosis and the search of other Flavivirus in suspected dengue cases with severe or atypical presentation. This work emphasizes the need to strengthen both the epidemiological surveillance of SLE, and vector control to prevent different infections transmitted by mosquitoes and to
Serologic evidence of the recent circulation of Saint Louis encephalitis virus and high prevalence of equine encephalitis viruses in horses in the Nhecolandia sub-region in South Pantanal, Central-West Brazil
Pauvolid-Corrêa, Alex;Tavares, Fernando Neto;Costa, Eliane Veiga da;Burlandy, Fernanda Marcicano;Murta, Michele;Pellegrin, Aiesca Oliveira;Nogueira, Márcia Furlan;Silva, Edson Elias da;
Memórias do Instituto Oswaldo Cruz , 2010, DOI: 10.1590/S0074-02762010000600017
Abstract: as in humans, sub-clinical infection by arboviruses in domestic animals is common; however, its detection only occurs during epizootics and the silent circulation of some arboviruses may remain undetected. the objective of the present paper was to assess the current circulation of arboviruses in the nhecolandia sub-region of south pantanal, brazil. sera from a total of 135 horses, of which 75 were immunized with bivalent vaccine composed of inactive eastern equine encephalitis virus (eeev) and western equine encephalitis virus(weev) and 60 were unvaccinated, were submitted to thorough viral isolation, reverse transcriptase polymerase chain reaction (rt-pcr) and neutralization tests for saint louis encephalitis virus (slev), eeev, weev and mayaro virus (mayv). no virus was isolated and viral nucleic-acid detection by rt-pcr was also negative. nevertheless, the prevalence of neutralizing antibodies in horses older than seven months was 43.7% for slev in equines regardless of vaccine status, and 36.4% for weev and 47.7% for eeev in unvaccinated horses. there was no evidence of mayv infections. the serologic evidence of circulation of arboviruses responsible for equine and human encephalitis, without recent official reports of clinical infections in the area, suggests that the nhecolandia sub-region in south pantanal is an important area for detection of silent activity of arboviruses in brazil.
An indirect immunofluorescence assay to detect antibodies against St. Louis Encephalitis virus
SPINSANTI, Lorena;RE, Viviana;AGUILAR, Javier;CONTIGIANI, Marta;
Revista do Instituto de Medicina Tropical de S?o Paulo , 2001, DOI: 10.1590/S0036-46652001000600008
Abstract: an in house indirect immmunofluorescence assay ( ifa ) in relation to neutralization (nt) reference test, was assessed as a fast and cheap method to carry out serological surveys for st. louis encephalitis virus (sle). sera obtained from 213 blood donors were analyzed by both tests. the prevalence of seropositivity obtained with ifa was lower than (30.98%) that observed on nt (41.78%). the relative specificity rate of ifa was 96.77% whereas its relative sensitivity rate was 69.66%. kappa index showed a good correlation between both tests. the results indicate that neutralization assay is still the serological test with the highest sensitivity and specificity relative rates for detecting antibodies against sle virus. nevertheless, the ifa could be useful as an alternative test in order to learn the circulation of the flavivirus genus in a certain area.
An indirect immunofluorescence assay to detect antibodies against St. Louis Encephalitis virus
SPINSANTI Lorena,RE Viviana,AGUILAR Javier,CONTIGIANI Marta
Revista do Instituto de Medicina Tropical de S?o Paulo , 2001,
Abstract: An in house indirect immmunofluorescence assay ( IFA ) in relation to neutralization (NT) reference test, was assessed as a fast and cheap method to carry out serological surveys for St. Louis Encephalitis virus (SLE). Sera obtained from 213 blood donors were analyzed by both tests. The prevalence of seropositivity obtained with IFA was lower than (30.98%) that observed on NT (41.78%). The relative specificity rate of IFA was 96.77% whereas its relative sensitivity rate was 69.66%. Kappa index showed a good correlation between both tests. The results indicate that neutralization assay is still the serological test with the highest sensitivity and specificity relative rates for detecting antibodies against SLE virus. Nevertheless, the IFA could be useful as an alternative test in order to learn the circulation of the Flavivirus genus in a certain area.
Isolation of Saint Louis Encephalitis Virus from a Horse with Neurological Disease in Brazil  [PDF]
Roberta Rosa,Erica Azevedo Costa,Rafael Elias Marques,Taismara Simas Oliveira,Ronaldo Furtini,Maria Rosa Quaresma Bomfim,Mauro Martins Teixeira,Tatiane Alves Paix?o,Renato Lima Santos
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002537
Abstract: St. Louis encephalitis virus (SLEV) is a causative agent of encephalitis in humans in the Western hemisphere. SLEV is a positive-sense RNA virus that belongs to the Flavivirus genus, which includes West Nile encephalitis virus, Japanese encephalitis virus, Dengue virus and other medically important viruses. Recently, we isolated a SLEV strain from the brain of a horse with neurological signs in the countryside of Minas Gerais, Brazil. The SLEV isolation was confirmed by reverse-transcription RT-PCR and sequencing of the E protein gene. Virus identity was also confirmed by indirect immunofluorescence using commercial antibodies against SLEV. To characterize this newly isolated strain in vivo, serial passages in newborn mice were performed and led to hemorrhagic manifestations associated with recruitment of inflammatory cells into the central nervous system of newborns. In summary this is the first isolation of SLEV from a horse with neurological signs in Brazil.
Two cases of Saint Louis encephalitis in HIV-1 infected patients in Buenos Aires
Viloria, Guillermo Alberto;Kundro, Mariana Angelica;Toibaro, Javier Jose;Seijo, Alfredo;Losso, Marcelo Horacio;
Brazilian Journal of Infectious Diseases , 2011, DOI: 10.1590/S1413-86702011000600019
Abstract: saint louis encephalitis virus (sle) is a mosquito borne disease. only a small proportion of cases progress to severe clinical forms. there have been few reports on hiv-infected patients and the relationship between immunodeficiency and the course of the disease remains unclear. herein we describe two cases of sle in hiv-1-infected patients in buenos aires city.
Serological detection of St. Louis encephalitis virus and West Nile virus in equines from Santa Fe, Argentina
Tauro, Laura;Marino, Betina;Diaz, Luis Adrian;Lucca, Eduardo;Gallozo, Debora;Spinsanti, Lorena;Contigiani, Marta;
Memórias do Instituto Oswaldo Cruz , 2012, DOI: 10.1590/S0074-02762012000400019
Abstract: st. louis encephalitis virus (slev) and west nile virus (wnv) present ecological and antigenic similarities and are responsible for serious human diseases. in addition, wnv is a significant pathogen in terms of equine health. the purpose of our study was to analyse the seroprevalence of slev and wnv in equine sera collected in santa fe province, argentina. the seroprevalence determined using the plaque reduction neutralisation test was 12.2% for slev, 16.2% for wnv and 48.6% for a combination of both viruses. these results provide evidence of the co-circulation of slev and wnv in equines in santa fe.
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