Seroepidemiology of bluetongue disease and risk factors in small ruminants of Shiraz suburb, Fars province, Iran.
3/12/2012 - IRAN, ISLAMIC REPUBLIC OF - NOT OFFICIAL - Published paper
Bluetongue virus (BTV) is a member of the genus Orbivirus in the family Reoviridae which is transmitted by insects and could cause considerable damages in sheep and goat flocks, such as mortality, decreased production and fertility, medical costs and commercial limits for flocks and their biologic production. As no study has been conducted on small ruminants about this disease in Fars province of Iran, the present study was conducted to determine the seroprevalence of the disease and some risk factors that might be related to it. A total of 200 serum samples were collected from 13 flocks including nomadic animals (70%) and resident flocks (30%) using a cluster random sampling method with an equal proportion of sheep and goats during the last three months of 2010. Some risk factors such as age, breed and abortion, exposure to other flocks, density and female replacement origin were reported in a question sheet. Totally, 73.5% of the samples were positive for presence of BTV antibody.The results showed that age and contact with other herds are influential risk factors on seroprevalence of the disease.
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Bluetongue virus serotype 8 virus-like particles protect sheep against virulent virus infection as a single or multi-serotype cocktail immunogen.
28/11/2012 - UNITED KINGDOM - NOT OFFICIAL - Published paper
Since 1998, there have been multiple separate outbreaks of Bluetongue disease (BT) in Europe with the largest outbreak ever recorded in Northern Europe caused by Bluetongue virus serotype 8 (BTV-8). Coinciding with the BTV-8 outbreak, a virulent strain of BTV-1 emerged and co-infections of these two serotypes were reported. In response, we generated VLPs for BTV-8 and tested the efficacy of BTV-8 VLPs as a single immunogen and as a component of a multivalent vaccine, with VLPs of BTV-1 and BTV-2, in order to test if there was any interference between serotypes. All pre-Alps sheep vaccinated with BTV-8 VLPs developed a strong neutralising antibody response to BTV-8 and multivalent VLP vaccinated animals also developed neutralising antibodies to BTV-1 and BTV-2. There were no side effects observed due to the vaccination with either the single- or multivalent VLP cocktail. All VLP-vaccinated animals had no clinical manifestation of BT or viraemia after challenge with a virulent BTV-8 isolate. This data indicates that BTV-8 VLPs delivered as a single immunogen or as a component of a multivalent vaccine are highly efficacious. Moreover, there was no interference on the development of a strong protective immune response due to the combination of different phylogenetically unrelated BTV serotypes in the vaccinated animals. This report further highlights that BTV VLPs are safe and efficacious immunogens that are able to afford complete protection against a virulent virus challenge.
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Predicting the spatio-temporal distribution of culicoides imicola in Sardinia using a discrete-time population model.
23/11/2012 - ITALY - NOT OFFICIAL - Published paper
ABSTRACT: BACKGROUND: Culicoides imicola KIEFFER, 1913 (Diptera: Ceratopogonidae) is the principal vector of Bluetongue disease in the Mediterranean basin, Africa and Asia. Previous studies have identified a range of eco-climatic variables associated with the distribution of C. imicola, and these relationships have been used to predict the large-scale distribution of the vector. However, these studies are not temporally-explicit and can not be used to predict the seasonality in C. imicola abundances. Between 2001 and 2006, longitudinal entomological surveillance was carried out throughout Italy, and provided a comprehensive spatio-temporal dataset of C. imicola catches in Onderstepoort-type black-light traps, in particular in Sardinia where the species is considered endemic. METHODS: We built a dynamic model that allows describing the effect of eco-climatic indicators on the monthly abundances of C. imicola in Sardinia. Model precision and accuracy were evaluated according to the influence of process and observation errors. RESULTS: A first-order autoregressive cofactor, a digital elevation model and MODIS Land Surface Temperature (LST)/or temperatures acquired from weather stations explained ~77 % of the variability encountered in the samplings carried out in 9 sites during 6 years. Incorporating Normalized Difference Vegetation Index (NDVI) or rainfall did not increase the model's predictive capacity. On average, dynamics simulations showed good accuracy (predicted vs. observed r corr = 0.9). Although the model did not always reproduce the absolute levels of monthly abundances peaks, it succeeded in reproducing the seasonality in population level and allowed identifying the periods of low abundances and with no apparent activity. On that basis, we mapped C. imicola monthly distribution over the entire Sardinian region. CONCLUSIONS: This study demonstrated prospects for modelling data arising from Culicoides longitudinal entomological surveillance. The framew...
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