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Stefania Thorgeirsdottir - One of the best experts on this subject based on the ideXlab platform.
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High incidence of Subclinical Infection of lymphoid tissues in scrapie-affected sheep flocks
Archives of Virology, 2008Co-Authors: Gudmundur Georgsson, Sigurdur Sigurdarson, Astridur Palsdottir, Jona Adalheidur Adolfsdottir, Einar Jorundsson, Stefania ThorgeirsdottirAbstract:Prion diseases are characterized by a long incubation period. In scrapie, sheep may incubate and spread the Infection for several years before clinical signs evolve. We have previously studied the occurrence of subclincal Infection in the brain. Now, we have studied the occurrence of Subclinical Infection in the brain and several lymphoid tissues in two scrapie-affected Icelandic sheep flocks by immunohistochemistry for PrP^Sc, a molecular marker for infectivity, and correlated this with results of PrP genotyping. At culling, one flock had one confirmed scrapie case, while the other flock had two. Analysis of 106 asymptomatic sheep by immunostaining for PrP^Sc revealed that the incidence of Subclinical Infection was 58.3% in one flock and 42.5% in the other. PrP^Sc was only detected in lymphoid tissues. The youngest positive sheep were 4 months old. PrP genotyping showed that over 90% of the sheep were of a genotype which is moderately sensitive to Infection and may delay neuroinvasion. Our results show that asymptomatic sheep may spread the Infection during the long incubation period of several years, which constitutes an important obstacle in the eradication of scrapie. Our findings indicate that contamination of the environment plays an important part in sustaining the Infection.
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Search for healthy carriers of scrapie: an assessment of Subclinical Infection of sheep in an Icelandic scrapie flock by three diagnostic methods and correlation with PrP genotypes.
Archives of virology, 2002Co-Authors: Stefania Thorgeirsdottir, Gudmundur Georgsson, E. Reynisson, Sigurdur Sigurdarson, Astridur PalsdottirAbstract:Subclinical Infection in scrapie of sheep, characterized by a long incubation period, may be of importance for the spread of the disease. We screened brain samples from all 65 sheep in a scrapie-affected flock for Subclinical Infection and correlated with results of PrP genotyping, which is of relevance for the epidemiology and the question, whether by breeding for resistant genotypes one would be breeding for healthy carriers. The sensitivity of three methods was compared, i.e. histopathological examination for vacuoles (HP), immunohistochemical staining (IHC) and Western blotting (WB) for PrPSc. Five sheep showed definite clinical signs and histological scrapie lesions, and signs of Infection were detected in 25 of 60 asymptomatic sheep, by HP and/or IHC and WB. The IHC was slightly more sensitive than HP and WB. Sheep with Subclinical Infection were, with one exception, either homo- or heterozygotes for 136-V, as were four of the five sheep with clinical scrapie. The incidence of the VRQ allelic variant in the flock was unusually high compared to the Icelandic sheep population probably contributing to the high prevalence of both clinical and Subclinical Infection in the flock. Neither sheep with definite scrapie nor detectable Subclinical Infection, were of the resistant AHQ genotype, indicating that Icelandic AHQ sheep are not healthy carriers of scrapie Infection.
Astridur Palsdottir - One of the best experts on this subject based on the ideXlab platform.
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High incidence of Subclinical Infection of lymphoid tissues in scrapie-affected sheep flocks
Archives of Virology, 2008Co-Authors: Gudmundur Georgsson, Sigurdur Sigurdarson, Astridur Palsdottir, Jona Adalheidur Adolfsdottir, Einar Jorundsson, Stefania ThorgeirsdottirAbstract:Prion diseases are characterized by a long incubation period. In scrapie, sheep may incubate and spread the Infection for several years before clinical signs evolve. We have previously studied the occurrence of subclincal Infection in the brain. Now, we have studied the occurrence of Subclinical Infection in the brain and several lymphoid tissues in two scrapie-affected Icelandic sheep flocks by immunohistochemistry for PrP^Sc, a molecular marker for infectivity, and correlated this with results of PrP genotyping. At culling, one flock had one confirmed scrapie case, while the other flock had two. Analysis of 106 asymptomatic sheep by immunostaining for PrP^Sc revealed that the incidence of Subclinical Infection was 58.3% in one flock and 42.5% in the other. PrP^Sc was only detected in lymphoid tissues. The youngest positive sheep were 4 months old. PrP genotyping showed that over 90% of the sheep were of a genotype which is moderately sensitive to Infection and may delay neuroinvasion. Our results show that asymptomatic sheep may spread the Infection during the long incubation period of several years, which constitutes an important obstacle in the eradication of scrapie. Our findings indicate that contamination of the environment plays an important part in sustaining the Infection.
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Search for healthy carriers of scrapie: an assessment of Subclinical Infection of sheep in an Icelandic scrapie flock by three diagnostic methods and correlation with PrP genotypes.
Archives of virology, 2002Co-Authors: Stefania Thorgeirsdottir, Gudmundur Georgsson, E. Reynisson, Sigurdur Sigurdarson, Astridur PalsdottirAbstract:Subclinical Infection in scrapie of sheep, characterized by a long incubation period, may be of importance for the spread of the disease. We screened brain samples from all 65 sheep in a scrapie-affected flock for Subclinical Infection and correlated with results of PrP genotyping, which is of relevance for the epidemiology and the question, whether by breeding for resistant genotypes one would be breeding for healthy carriers. The sensitivity of three methods was compared, i.e. histopathological examination for vacuoles (HP), immunohistochemical staining (IHC) and Western blotting (WB) for PrPSc. Five sheep showed definite clinical signs and histological scrapie lesions, and signs of Infection were detected in 25 of 60 asymptomatic sheep, by HP and/or IHC and WB. The IHC was slightly more sensitive than HP and WB. Sheep with Subclinical Infection were, with one exception, either homo- or heterozygotes for 136-V, as were four of the five sheep with clinical scrapie. The incidence of the VRQ allelic variant in the flock was unusually high compared to the Icelandic sheep population probably contributing to the high prevalence of both clinical and Subclinical Infection in the flock. Neither sheep with definite scrapie nor detectable Subclinical Infection, were of the resistant AHQ genotype, indicating that Icelandic AHQ sheep are not healthy carriers of scrapie Infection.
Sérgio Paulo Bydlowski - One of the best experts on this subject based on the ideXlab platform.
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Detection of Plasmodium falciparum and Plasmodium vivax Subclinical Infection in non-endemic region: implications for blood transfusion and malaria epidemiology
Malaria journal, 2014Co-Authors: Luciana Morganti Ferreira Maselli, Debora Levy, Gabriel Zorello Laporta, Aline M Monteiro, Linah Akemi Fukuya, Maria De Fátima Ferreira-da-cruz, Cláudio Tadeu Daniel-ribeiro, Pedro Enrique Dorlhiac-llacer, Maria Anice Mureb Sallum, Sérgio Paulo BydlowskiAbstract:Background In Brazil, malaria is endemic in the Amazon River basin and non-endemic in the extra-Amazon region, which includes areas of Sao Paulo state. In this state, a number of autochthonous cases of malaria occur annually, and the prevalence of Subclinical Infection is unknown. Asymptomatic Infections may remain undetected, maintaining transmission of the pathogen, including by blood transfusion. In these report it has been described Subclinical Plasmodium Infection in blood donors from a blood transfusion centre in Sao Paulo, Brazil.
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detection of plasmodium falciparum and plasmodium vivax Subclinical Infection in non endemic region implications for blood transfusion and malaria epidemiology
Malaria Journal, 2014Co-Authors: Luciana Morganti Ferreira Maselli, Debora Levy, Gabriel Zorello Laporta, Aline M Monteiro, Linah Akemi Fukuya, Maria Anice Mureb Sallum, Maria De Fatima Ferreiradacruz, Claudio Tadeu Danielribeiro, Pedro Enrique Dorlhiacllacer, Sérgio Paulo BydlowskiAbstract:Background: In Brazil, malaria is endemic in the Amazon River basin and non-endemic in the extra-Amazon region, which includes areas of Sao Paulo state. In this state, a number of autochthonous cases of malaria occur annually, and the prevalence of Subclinical Infection is unknown. Asymptomatic Infections may remain undetected, maintaining transmission of the pathogen, including by blood transfusion. In these report it has been described Subclinical Plasmodium Infection in blood donors from a blood transfusion centre in Sao Paulo, Brazil. Methods: In this cross-sectional study, representative samples of blood were obtained from 1,108 healthy blood donors at the Fundacao Pro-Sangue Hemocentro de Sao Paulo, the main blood transfusion centre in Sao Paulo. Malaria exposure was defined by the home region (exposed: forest region; non-exposed: non-forest region). Real-time PCR was used to detect Plasmodium falciparum and Plasmodium vivax. Subclinical malaria cases were geo-referenced. Results: Eighty-four (7.41%) blood donors tested positive for Plasmodium; 57 of these were infected by P. falciparum, 25 by P. vivax, and 2 by both. The prevalence of P. falciparum and P. vivax was 5.14 and 2.26, respectively. The overall prevalence ratio (PR) was 3.23 (95% confidence interval (CI) 2.03, 5.13); P. falciparum PR was 16.11 (95% CI 5.87, 44.21) and P. vivax PR was 0.47 (95% CI 0.2, 1.12). Plasmodium falciparum Subclinical malaria Infection in the Atlantic Forest domain was present in the mountain regions while P. vivax Infection was observed in cities from forest-surrounded areas. Conclusions: The presence ofPlasmodium in healthy blood donors from a region known as non-endemic, which is important in the context of transfusion biosafety, was described. Infected recipients may become asymptomatic carriers and a reservoir for parasites, maintaining their transmission. Furthermore, P. falciparum PR was positively associated with the forest environment, and P. vivax was associated with forest fragmentation.
Barbara Wieland - One of the best experts on this subject based on the ideXlab platform.
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economic efficiency analysis of different strategies to control post weaning multi systemic wasting syndrome and porcine circovirus type 2 Subclinical Infection in 3 weekly batch system farms
Preventive Veterinary Medicine, 2013Co-Authors: Pablo Alarcon, Jonathan Rushton, Heiko Nathues, Barbara WielandAbstract:The study assessed the economic efficiency of different strategies for the control of post-weaning multi-systemic wasting syndrome (PMWS) and porcine circovirus type 2 Subclinical Infection (PCV2SI), which have a major economic impact on the pig farming industry worldwide. The control strategies investigated consisted on the combination of up to 5 different control measures. The control measures considered were: (1) PCV2 vaccination of piglets (vac); (2) ensuring age adjusted diet for growers (diets); (3) reduction of stocking density (stock); (4) improvement of biosecurity measures (bios); and (5) total depopulation and repopulation of the farm for the elimination of other major pathogens (DPRP). A model was developed to simulate 5 years production of a pig farm with a 3-weekly batch system and with 100 sows. A PMWS/PCV2SI disease and economic model, based on PMWS severity scores, was linked to the production model in order to assess disease losses. This PMWS severity scores depends on the combination post-weaning mortality, PMWS morbidity in younger pigs and proportion of PCV2 infected pigs observed on farms. The economic analysis investigated eleven different farm scenarios, depending on the number of risk factors present before the intervention. For each strategy, an investment appraisal assessed the extra costs and benefits of reducing a given PMWS severity score to the average score of a slightly affected farm. The net present value obtained for each strategy was then multiplied by the corresponding probability of success to obtain an expected value. A stochastic simulation was performed to account for uncertainty and variability. For moderately affected farms PCV2 vaccination alone was the most cost-efficient strategy, but for highly affected farms it was either PCV2 vaccination alone or in combination with biosecurity measures, with the marginal profitability between 'vac' and 'vac+bios' being small. Other strategies such as 'diets', 'vac+diets' and 'bios+diets' were frequently identified as the second or third best strategy. The mean expected values of the best strategy for a moderately and a highly affected farm were £14,739 and £57,648 after 5 years, respectively. This is the first study to compare economic efficiency of control strategies for PMWS and PCV2SI. The results demonstrate the economic value of PCV2 vaccination, and highlight that on highly affected farms biosecurity measures are required to achieve optimal profitability. The model developed has potential as a farm-level decision support tool for the control of this economically important syndrome.
Gudmundur Georgsson - One of the best experts on this subject based on the ideXlab platform.
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High incidence of Subclinical Infection of lymphoid tissues in scrapie-affected sheep flocks
Archives of Virology, 2008Co-Authors: Gudmundur Georgsson, Sigurdur Sigurdarson, Astridur Palsdottir, Jona Adalheidur Adolfsdottir, Einar Jorundsson, Stefania ThorgeirsdottirAbstract:Prion diseases are characterized by a long incubation period. In scrapie, sheep may incubate and spread the Infection for several years before clinical signs evolve. We have previously studied the occurrence of subclincal Infection in the brain. Now, we have studied the occurrence of Subclinical Infection in the brain and several lymphoid tissues in two scrapie-affected Icelandic sheep flocks by immunohistochemistry for PrP^Sc, a molecular marker for infectivity, and correlated this with results of PrP genotyping. At culling, one flock had one confirmed scrapie case, while the other flock had two. Analysis of 106 asymptomatic sheep by immunostaining for PrP^Sc revealed that the incidence of Subclinical Infection was 58.3% in one flock and 42.5% in the other. PrP^Sc was only detected in lymphoid tissues. The youngest positive sheep were 4 months old. PrP genotyping showed that over 90% of the sheep were of a genotype which is moderately sensitive to Infection and may delay neuroinvasion. Our results show that asymptomatic sheep may spread the Infection during the long incubation period of several years, which constitutes an important obstacle in the eradication of scrapie. Our findings indicate that contamination of the environment plays an important part in sustaining the Infection.
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Search for healthy carriers of scrapie: an assessment of Subclinical Infection of sheep in an Icelandic scrapie flock by three diagnostic methods and correlation with PrP genotypes.
Archives of virology, 2002Co-Authors: Stefania Thorgeirsdottir, Gudmundur Georgsson, E. Reynisson, Sigurdur Sigurdarson, Astridur PalsdottirAbstract:Subclinical Infection in scrapie of sheep, characterized by a long incubation period, may be of importance for the spread of the disease. We screened brain samples from all 65 sheep in a scrapie-affected flock for Subclinical Infection and correlated with results of PrP genotyping, which is of relevance for the epidemiology and the question, whether by breeding for resistant genotypes one would be breeding for healthy carriers. The sensitivity of three methods was compared, i.e. histopathological examination for vacuoles (HP), immunohistochemical staining (IHC) and Western blotting (WB) for PrPSc. Five sheep showed definite clinical signs and histological scrapie lesions, and signs of Infection were detected in 25 of 60 asymptomatic sheep, by HP and/or IHC and WB. The IHC was slightly more sensitive than HP and WB. Sheep with Subclinical Infection were, with one exception, either homo- or heterozygotes for 136-V, as were four of the five sheep with clinical scrapie. The incidence of the VRQ allelic variant in the flock was unusually high compared to the Icelandic sheep population probably contributing to the high prevalence of both clinical and Subclinical Infection in the flock. Neither sheep with definite scrapie nor detectable Subclinical Infection, were of the resistant AHQ genotype, indicating that Icelandic AHQ sheep are not healthy carriers of scrapie Infection.
