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Search Results: 1 - 10 of 331253 matches for " Marta S. Contigiani "
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Silent Circulation of St. Louis Encephalitis Virus Prior to an Encephalitis Outbreak in Cordoba, Argentina (2005)
Luis Adrian Díaz ,Guillermo Albrieu Llinás,Ana Vázquez,Antonio Tenorio,Marta Silvia Contigiani
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001489
Abstract: St. Louis encephalitis virus is a complex zoonoses. In 2005, 47 laboratory-confirmed and probable clinical cases of SLEV infection were reported in Córdoba, Argentina. Although the causes of 2005 outbreak remain unknown, they might be related not only to virological factors, but also to ecological and environmental conditions. We hypothesized that one of the factors for SLE reemergence in Córdoba, Argentina, was the introduction of a new SLEV genotype (SLEV genotype III), with no previous activity in the area. In order to evaluate this hypothesis we carried out a molecular characterization of SLEV detections from mosquitoes collected between 2001 and 2004 in Córdoba city. A total of 315 mosquito pools (11,002 individuals) including 12 mosquitoes species were analyzed. Overall, 20 pools (8 mosquitoes species) were positive for SLEV. During this study, genotypes II, V and VII were detected. No mosquito pool infected with genotype III was detected before the 2005 outbreak. Genotype V was found every year and in the 8 sampled sites. Genotypes II and VII showed limited temporal and spatial activities. We cannot dismiss the association of genotype II and V as etiological agents during the outbreak. However, the silent circulation of other SLEV strains in Córdoba city before the 2005 outbreak suggests that the introduction of genotype III was an important factor associated to this event. Not mutually exclusive, other factors such as changes in avian hosts and mosquitoes vectors communities, driven by climatic and environmental modifications, should also be taken into consideration in further studies.
Comparison of Argentinean Saint Louis Encephalitis Virus Non-Epidemic and Epidemic Strain Infections in an Avian Model
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.
Evaluation of five screening tests licensed in Argentina for detection of hepatitis C virus antibodies
, Viviana;Gallego, Sandra;Trevi?o, Elena;Barbás, Gabriela;Domínguez, Claudia;Elbarcha, Osvaldo;Bepre, Héctor;Contigiani, Marta;
Memórias do Instituto Oswaldo Cruz , 2005, DOI: 10.1590/S0074-02762005000300016
Abstract: this study was conducted to compare among the most recent generation of five screening tests licensed in argentina, in order to evaluate which of the tests has the best sensitivity for detection of antibodies against hepatitis c virus (hcv). the tests analyzed were: detect-hcv? (3.0) biochem immunosystems, canada; hepatitis c eia wiener lab., argentina; equipar hcv ab, italy; murex hcv 4.0, uk and serodia-hcv particles agglutination test, japan. the results obtained showed high discrepancy between the different kits used and show that some of the tests assessed have a low sensitivity for anti-hcv detection in both chronic infections and early seroconversion, and indicate that among the commercially available kits in argentina, murex hcv 4.0 (uk) and serodia-hcv particles agglutination test (japan) have the best sensitivity for hcv screening. although the sensitivity of the assays is the first parameter to be considered for blood screening, more studies should be carried out to assess the specificity of such assays.
Phylodynamics of Hepatitis C Virus Subtype 2c in the Province of Córdoba, Argentina
Viviana E. Ré,Andrés C. A. Culasso,Silvia Mengarelli,Adrián A. Farías,Fabián Fay,María B. Pisano,Osvaldo Elbarcha,Marta S. Contigiani,Rodolfo H. Campos
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019471
Abstract: The Hepatitis C Virus Genotype 2 subtype 2c (HCV-2c) is detected as a low prevalence subtype in many countries, except in Southern Europe and Western Africa. The current epidemiology of HCV in Argentina, a low-prevalence country, shows the expected low prevalence for this subtype. However, this subtype is the most prevalent in the central province of Córdoba. Cruz del Eje (CdE), a small rural city of this province, shows a prevalence for HCV infections of 5%, being 90% of the samples classified as HCV-2c. In other locations of Córdoba Province (OLC) with lower prevalence for HCV, HCV-2c was recorded in about 50% of the samples. The phylogenetic analysis of samples from Córdoba Province consistently conformed a monophyletic group with HCV-2c sequences from all the countries where HCV-2c has been sequenced. The phylogeographic analysis showed an overall association between geographical traits and phylogeny, being these associations significant (α = 0.05) for Italy, France, Argentina (places other than Córdoba), Martinique, CdE and OLC. The coalescence analysis for samples from CdE, OLC and France yielded a Time for the Most Common Recent Ancestor of about 140 years, whereas its demographic reconstruction showed a “lag” phase in the viral population until 1880 and then an exponential growth until 1940. These results were also obtained when each geographical area was analyzed separately, suggesting that HCV-2c came into Córdoba province during the migration process, mainly from Europe, which is compatible with the history of Argentina of the early 20th century. This also suggests that the spread of HCV-2c occurred in Europe and South America almost simultaneously, possibly as a result of the advances in medicine technology of the first half of the 20th century.
Identification of hepatitis C virus subtype 2c by sequencing analysis in patients from Córdoba, Argentina
, Viviana;Contigiani, Marta;Yoshida, Clara Fumiko Tachibana;Lampe, Elisabeth;
Memórias do Instituto Oswaldo Cruz , 2007, DOI: 10.1590/S0074-02762007000800016
Abstract: in argentina, most information on hepatitis c virus (hcv) genotype distribution comes from studies carried out in buenos aires (east province). in order to identify hcv subtypes in central argentina, nucleotide sequencing of core region was performed in samples from 36 patients living in córdoba, the second most populated province of argentina. the sequence analysis identified subtype 2c as the most prevalent (50%), followed by subtype 1b (33%) and to a lesser extent by subtypes 1a (11%), 3a (3%) and 4a (3%). this is the first report of circulation of hcv subtype 2c in this region of argentina and also such high prevalence has never been found before in the genotype distribution of south america.
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.
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.
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.
Seroprevalence of antibodies to Venezuelan equine encephalitis complex (subtypes IAB and VI) in humans from General Belgrano Island, Formosa, Argentina
Cámara, Alicia;Díaz, Gladis;Vega, Victor;Basualdo, María;Contigiani, Marta;
Revista do Instituto de Medicina Tropical de S?o Paulo , 2003, DOI: 10.1590/S0036-46652003000400005
Abstract: this work presents the results of the detection of antibodies (immunoglobulin g) for subtypes i and vi of vee viruses complex (togaviridae family) in people from the general belgrano island, formosa province (argentina). the prevalence of neutralizing (nt) antibodies for subtype vi was from 30% to 70% and the prevalence of antibodies inhibitory of hemagglutination (hi) was of 0% in the first and second inquiry respectively. for the subtype iab the prevalence of nt antibodies was from 13% to 3.6%, similar to the prevalence total for both subtypes. hi antibodies were not detected in any inquiries for any subtype. it was observed that both subtypes circulate simultaneously, while subtype vi remains constant with some peaks, subtype i was found in low level.
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