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Design, sampling and data interpretation constitute an important challenge for wildlife surveillance of avian influenza viruses (AIV). The aim of this study was to construct a model to improve and enhance identification in both different periods and locations of avian species likely at high risk of contact with AIV in a specific wetland. This study presents an individualbased stochastic model for the Ebre Delta as an example of this appliance. Based on the Monte-Carlo method, the model simulates the dynamics of the spread of AIV among wild birds in a natural park following introduction of an infected bird. Data on wild bird species population, apparent AIV prevalence recorded in wild birds during the period of study, and ecological information on factors such as behaviour, contact rates or patterns of movements of waterfowl were incorporated as inputs of the model. From these inputs, the model predicted those species that would introduce most of AIV in different periods and those species and areas that would be at high risk as a consequence of the spread of these AIV incursions. This method can serve as a complementary tool to previous studies to optimize the allocation of the limited AI surveillance resources in a local complex ecosystem. However, this study indicates that in order to predict the evolution of the spread of AIV at the local scale, there is a need for further research on the identification of host factors involved in the interspecies transmission of AIV

In this paper we report the synthesis and characterization of biocompatible multi-functional magnetic nanoparticles (MNPs) able to enhance the intracellular transport of N-methylated drugs. The Fe3O4 magnetic core was first functionalized with a mixed monolayer consisting of two different phosphonic acids having terminal acetylenic and amino groups, which provide an active platform for further functionalization with organic molecules. Then, a tetraphosphonate cavitand receptor (Tiiii) bearing an azide moiety and the N-hydroxysuccinimide (NHS) activated forms of poly(ethylene glycol) (PEG), folic acid (FA) and carboxy-X-rhodamine (Rhod) were covalently anchored on alkyne and amine moieties respectively, through 1,3-dipolar cycloaddition and EDC/NHS coupling reactions. The obtained MNPs are biocompatible and possess magnetic, luminescence and recognition properties which make them suitable for multimodal theranostic applications. In particular, combined confocal microscopy and cytotoxicity experiments showed that these multi-functional MNPs are able to recognize a specific drug "in situ'' and promote its cellular internalization, thus enhancing its efficiency.

In this article we present a new INteger-valued AutoRegressive (INAR) model with the aim of extracting baseline patterns of cattle fallen stock registered over an 5-year period at a local scale. We introduce HINAR as a generalization of the classical Poisson-based INAR models whose innovations follow a Hermite distribution. In order to assess trends and seasonality in these time series, we fit different models with time-dependent parameters by specifying proper functions. Using real world examples, we illustrate how to estimate parameters by maximum likelihood and validate the fitted models. We also show a detailed method to forecast. Our proposed model supposes a good solution for studying discrete time series when the counts have many zeros, low counts and moderate overdispersion. This model has been applied to the analysis of fallen cattle registered at a local scale as part of the development of a veterinary syndromic surveillance system.

Swine and poultry viruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine epidemic diarrhea virus (PEDV), and highly pathogenic avian influenza virus (HPAIV), are economically important pathogens that can spread via aerosols. The reliability of methods for quantifying particle-associated viruses as well as the size distribution of aerosolized particles bearing these viruses under field conditions are not well documented. We compared the performance of 2 size-differentiating air samplers in disease outbreaks that occurred in swine and poultry facilities. Both air samplers allowed quantification of particles by size, and measured concentrations of PRRSV, PEDV, and HPAIV stratified by particle size both within and outside swine and poultry facilities. All 3 viruses were detectable in association with aerosolized particles. Proportions of positive sampling events were 69% for PEDV, 61% for HPAIV, and 8% for PRRSV. The highest virus concentrations were found with PEDV, followed by HPAIV and PRRSV. Both air collectors performed equally for the detection of total virus concentration. For all 3 viruses, higher numbers of RNA copies were associated with larger particles; however, a bimodal distribution of particles was observed in the case of PEDV and HPAIV.

Given that Newcastle disease (ND) is one of the major threats for the poultry industry, testing of Newcastle disease virus (NDV) has been carried out since 2010 in cases of mortality in wild birds (passive surveillance) in Catalonia. The objective is to provide an early warning system to prevent the infection of poultry. Since 2010, 35 episodes of mortality in wild birds were attributed to NDV infection. Throughout this period there was a progressive expansion of NDV to new areas, with an increase in the episodes of mortality, although it is not clear whether they were the result of the spread of the virus, or of the improvement of the surveillance. Phylogenetic analyses indicate that two distinct sublineages of NDV, 4a and 4b, were circulating in Catalonia. Both sublineages seem to be endemic in the wild bird population, affecting mainly Eurasian-collared doves, with a clear pattern in relation to its spatial distribution (coincident with the distribution of this species), and its temporal distribution (with the majority of cases between September and February). So far, endemicity in wild birds has not resulted in ND outbreaks in poultry. However, there are still many uncertainties about, for example, whether NDV may expand to new areas of Catalonia (with higher poultry density), or about the threat that the apparently more novel sublineage 4a may represent. Hence, efforts should be made so that measures to prevent infection of poultry farms (particularly in high-risk areas and periods) are encouraged, and surveillance is maintained.

The reporting and monitoring of swine enteric coronavirus diseases (SECD), including porcine epidemic diarrhea virus and porcine delta coronavirus, in the United States have been challenging because of the initial absence of a regulatory framework and the emerging nature of these diseases. The National Animal Health Laboratory Network, the Emergency Management and Response System, and the Swine Health Monitoring Project were used to monitor the disease situation between May 2013 and March 2015. Important differences existed between and among them in terms of nature and extent of reporting. Here, we assess the implementation of these systems from different perspectives, including a description and comparison of collected data, disease metrics, usefulness, simplicity, flexibility, acceptability, representativeness, timeliness, and stability. This assessment demonstrates the limitations that the absence of premises identification imposes on certain animal health surveillance and response databases, and the importance of federally regulated frameworks in collecting accurate information in a timely manner. This study also demonstrates the value that the voluntary and producer-organized systems may have in monitoring emerging diseases. The results from all three data sources help to establish the baseline information on SECD epidemiological dynamics after almost 3 years of disease occurrence in the country.

The antibacterial activity and possible toxicity of graphene oxide and laser-irradiated graphene oxide (iGO) were investigated. Antibacterial activity was tested on Escherichia coli and shown to be higher for GO irradiated for at least three hours, which seems to be correlated to the resulting morphology of laser-treated GO and independent of the kind and amount of oxygen functionalities. X-ray photoelectron spectroscopy, Raman spectroscopy, dynamic light scattering and scanning electron microscopy (SEM) show a reduction of the GO flakes size after visible laser irradiation, preserving considerable oxygen content and degree of hydrophilicity. SEM images of the bacteria after the exposure to the iGO flakes confirm membrane damage after interaction with the laser-modified morphology of GO. In addition, a fish embryo toxicity test on zebrafish displayed that neither mortality nor sublethal effects were caused by the different iGO solutions, even when the concentration was increased up to four times higher than the one effective in reducing the bacteria survival. The antibacterial properties and the absence of toxicity make the visible laser irradiation of GO a promising option for water purification applications.

Industry-driven voluntary disease control programs for swine diseases emerged in North America in the early 2000's, and, since then, those programs have been used for monitoring diseases of economic importance to swine producers. One example of such initiatives is Dr. Morrison's Swine Health Monitoring Project, a nation-wide monitoring program for swine diseases including the porcine reproductive and respiratory syndrome (PRRS). PRRS has been extensively reported as a seasonal disease in the U.S., with predictable peaks that start in fall and are extended through the winter season. However, formal time series analysis stratified by geographic region has never been conducted for this important disease across the U.S. The main objective of this study was to use approximately seven years of PRRS incidence data in breeding swine herds to conduct time-series analysis in order to describe the temporal patterns of PRRS outbreaks at the farm level for five major swine-producing states across the U.S. including the states of Minnesota, Iowa, North Carolina, Nebraska and Illinois. Data was aggregated retrospectively at the week level for the number of herds containing animals actively shedding PRRS virus. Basic descriptive statistics were conducted followed by autoregressive integrated moving average (ARIMA) modelling, conducted separately for each of the above-mentioned states. Results showed that there was a difference in the nature of PRRS seasonality among states. Of note, when comparing states, the typical seasonal pattern previously described for PRRS could only be detected for farms located in the states of Minnesota, North Carolina and Nebraska. For the other two states, seasonal peaks every six months were detected within a year. In conclusion, we showed that epidemic patterns are not homogeneous across the U.S, with major peaks of disease occurring through the year. These findings highlight the importance of coordinating alternative control strategies in different regions considering the prevailing epidemiological patterns.

Serum samples from 210 wild ruminants collected between 2006 and 2007 in southern Spain were tested for antibodies against bluetongue virus (BTV) by means of a competitive ELISA assay. Eighty-seven of the 210 wild ruminants analysed (41%) showed antibodies against BTV. Statistically significant differences were found in the seroprevalence among species: 66% (65 of 98) for red deer (Cervus elaphus), 50% (ten of 20) for fallow deer (Dama dama), 33% (three of nine) for mouflon (Ovis aries musimon) and 11% (nine of 83) for Spanish ibex (Capra pyrenaica). Overall, the sites where seropositive wild ruminants were found coincide with the areas where BTV had been detected in livestock, but in eastern Sierra Morena, the virus circulated in wild ruminants, although it had not been detected in domestic ruminants in the same areas. Wild ruminants over 1-year of age (sub-adults and adults) had significantly higher seroprevalences than juvenile animals. Statistically significant differences were also observed between BTV seroprevalence and management (free-ranging vs. captivity) with higher prevalence in free-ranging animals. The high seroprevalences obtained suggest that BTV is widespread in wild ruminants in southern Spain. This factor could have an important influence on the evolution of the infection in domestic livestock and indicates the need to include wild ruminant species in BTV surveillance or control programs.

During the period 2004–2005 a serological survey was conducted in sheep flocks in Catalonia (North-Eastern Spain) in order to determine the seroprevalence of maedi-visna virus (MVV) and pestiviruses, such as Border Disease Virus (BDV), to investigate their spatial distribution and to obtain information about associations between them for planning and prioritizing the control measures in this region. A random sample of 241 sheep flocks stratified by counties was analyzed. A total of 5120 and 3611 animals were tested using different indirect ELISA methods for MVV and pestiviruses, respectively. The results showed that MVV and pestiviruses were very widespread in Catalonia. Ninety percent of sheep flocks were positive for MVV and sixty four percent were positive for Pestivirus genus. The spatial distributions of both viral pathogens were not homogenous: MVV seroprevalence within flock was higher in North-Western and Western Catalonia, whereas the antibody proportion of pestiviruses at the flock-level and within flock was higher in North-Western Catalonia. Large flocks had higher seroprevalences within flock than smaller ones. Mixed flocks showed higher risk of MVV infection than purely sheep flocks and there was a statistical association between MVV and pestivirus seroprevalence.

Porcine reproductive and respiratory syndrome virus (PRRSv) infection causes a devastating economic impact to the swine industry. Active surveillance is routinely conducted in many swine herds to demonstrate freedom from PRRSv infection. The design of efficient active surveillance sampling schemes is challenging because optimum surveillance strategies may differ depending on infection status, herd structure, management, or resources for conducting sampling. Here, we present an open web-based application, named ‘OptisampleTM’, designed to optimize herd sampling strategies to substantiate freedom of infection considering also costs of testing. In addition to herd size, expected prevalence, test sensitivity, and desired level of confidence, the model takes into account the presumed risk of pathogen introduction between samples, the structure of the herd, and the process to select the samples over time. We illustrate the functionality and capacity of ‘OptisampleTM’ through its application to active surveillance of PRRSv in hypothetical swine herds under disparate epidemiological situations. Diverse sampling schemes were simulated and compared for each herd to identify effective strategies at low costs. The model results show that to demonstrate freedom from disease, it is important to consider both the epidemiological situation of the herd and the sample selected. The approach illustrated here for PRRSv may be easily extended to other animal disease surveillance systems using the web-based application available at http://stemma.ahc.umn.edu/optisample.

Antibodies against bluetongue virus were detected in cattle, sheep, goats, and camels in Algeria in 2008. Antibodies against epizootic hemorrhagic disease virus were detected in cattle, but antibodies against African horse sickness virus were not detected in horses and mules. Epizootic hemorrhagic disease in northern Africa poses a major risk for the European Union.

Six serological assays for the diagnosis of ovine brucellosis, due to Brucella melitensis were evaluated. Reference serum samples from sheep of known B. melitensis infection status ( n = 118) were assessed using the Rose Bengal test (RBT), complement fixation test (CFT) and four commercial enzyme-linked immunosorbent assays (ELISAs), including two indirect ELISAs (iELISAs), one competitive ELISA (cELISA) and one blocking ELISA (bELISA). The highest differential positive rates (DPR) were obtained with the cELISA and bELISA, while the lowest DPR was estimated using iELISAs. A latent class analysis was performed to estimate the accuracy of the CFT, RBT and bELISA using 1827 sera from sheep undergoing testing as part of a surveillance and control programme. Lower sensitivity and specificity were obtained for the three serological tests when the field samples were used. A higher DPR was achieved by the CFT, compared to bELISA and RBT. The results suggest that ELISAs, and particularly the bELISA, might be suitable for inclusion in the European Union legislation on intra-community trade for diagnosing B. melitensis infection in sheep, as it has a similar test performance compared to the RBT.

Even though bluetongue virus (BTV) transmission is apparently interrupted during winter, bluetongue outbreaks often reappear in the next season (overwintering). Several mechanisms for BTV overwintering have been proposed, but to date, their relative importance remain unclear. In order to assess the probability of BTV overwintering by persistence in adult vectors, ruminants (through prolonged viraemia) or a combination of both, a quantitative risk assessment model was developed. Furthermore, the model allowed the role played by the residual number of vectors present during winter to be examined, and the effect of a proportion of Culicoides living inside buildings (endophilic behaviour) to be explored. The model was then applied to a real scenario: overwintering in Germany between 2006 and 2007. The results showed that the limited number of vectors active during winter seemed to allow the transmission of BTV during this period, and that while transmission was favoured by the endophilic behaviour of some Culicoides, its effect was limited. Even though transmission was possible, the likelihood of BTV overwintering by the mechanisms studied seemed too low to explain the observed re-emergence of the disease. Therefore, other overwintering mechanisms not considered in the model are likely to have played a significant role in BTV overwintering in Germany between 2006 and 2007.

Selection of an ideal sample is a vital element in early detection of influenza infection. Rapid identification of infectious individuals or animals is crucial not only for avian influenza virus (AIV) surveillance programmes, but also for treatment and containment strategies. This study used a combination of quantitative real-time RT-PCR with an internal positive control and a cell-titration system to examine the presence of virus in different samples during active experimental AIV infection and its persistence in the infected carcasses. Oropharyngeal/cloacal swabs as well as feather pulp and blood samples were collected from 15-day-old chicks infected with H7N1 highly pathogenic AIV (HPAIV) and the kinetics of virus shedding during active infection were evaluated. Additionally, several samples (muscle, skin, brain, feather pulp and oropharyngeal and cloacal swabs) were examined to assess the persistence of virus in the HPAIV-infected carcasses. Based on the results, feather pulp was found to be the best sample to detect and isolate HPAIV from infected chicks from 24 h after inoculation onwards. Kinetic studies on the persistence of virus in infected carcasses revealed that tissues such as muscle could potentially transmit infectious virus for 3 days post-mortem (p.m.), whilst other tissues such as skin, feather pulp and brain retained their infectivity for as long as 5-6 days p.m. at environmental temperature (22-23 degrees C). These results strongly favour feather as a useful sample for HPAIV diagnosis in infected chickens as well as in carcasses.

The potential of fallen stock data to monitor the health status of animal populations has been noted in previous studies. However, further research is required to implement these systems for surveillance. This work presents a novel approach to determining the baselines associated with bovine fallen stock, comparing patterns between subpopulations and identifying subpopulations in which an abnormal event may occur. This study was based on data from 193,873 disposal visits carried out between 2004 and 2012 across a total of 2,991 bovine farms. Proxy measurements such as the number of collections carried out and the weight of carcasses collected were used. Both outcomes were aggregated weekly at different geographical scales for three production types (beef cattle, dairy cattle and heifer fattening). The analysis of these data combined autoregressive integrated moving average modelling and hierarchical time series methods.The three production types exhibited historical baselines that differed notably from one another. Based on the 757 beef cattle farms monitored, the mean number of collections registered per week at the regional level was 37 (range: 10–83). This series was relatively constant over time and showed a marked yearly seasonality. In contrast, for the 426 dairy cattle farms the mean number of disposal visits registered weekly was 121 (range: 71–180), showing half-yearly and yearly seasonality and a marked increase over the period monitored. From the 1,808 heifer fattening farms the mean number of disposal visits was 248 (range: 166–357) and the pattern presented a marked alternating trend over time. These patterns were assessed and compared at regional, provincial, county and municipal levels. The use of hierarchical time series approaches appeared to be a useful tool for comparing the patterns within different subpopulations over time as well as for assessing the spatial extent to which various abnormal events could be detected. info:eu-repo/semantics/publishedVersion

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al., Studies exploring the ecological interactions between avian influenza viruses (AIV), natural hosts and the environment are scarce. Most work has focused on viral survival and transmission under laboratory conditions and through mathematical modelling. However, more integrated studies performed under field conditions are required to validate these results. In this study, we combined information on bird community, environmental factors and viral epidemiology to assess the contribution of biotic and abiotic factors in the occurrence of low pathogenic AIV in Spanish wetlands. For that purpose, seven locations in five different wetlands were studied during two years (2007-2009), including seven sampling visits by location. In each survey, fresh faeces (n = 4578) of wild birds and water samples were collected for viral detection. Also, the vegetation structure, water physical properties of wetlands, climatic conditions and wild bird community composition were determined. An overall AIV prevalence of 1.7%±0.4 was detected in faecal samples with important fluctuations among seasons and locations. Twenty-six AIV were isolated from the 78 RRT-PCR positive samples and eight different haemagglutinines and five neuraminidases were identified, being the combination H3N8 the most frequent. Variation partitioning procedures identified the combination of space and time variables as the most important pure factor - independently to other factors - explaining the variation in AIV prevalence (36.8%), followed by meteorological factor (21.5%) and wild bird community composition/vegetation structure (21.1%). These results contribute to the understanding of AIV ecological drivers in Spanish ecosystems and provide useful guidelines for AIV risk assessment identifying potential hotspots of AIV activity., This work was financially supported by INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria), project FAU2006-00019-C03-00 and by Department of Environment, Territorial Planning, Agriculture and Fisheries of the Basque Government. P. Acevedo was supported by a Beatriu de Pinós fellowship funded by Comissionat per a Universitats i Recerca del Departament d'Innovació, Universitats i Empresa, of the Generalitat de Catalunya and the COFUND Programme-Marie Curie Actions under 7th Marc Programme of the European Community.

In August 2006, a bluetongue outbreak was detected in the Netherlands. It was caused by bluetongue virus serotype 8 (BTV- 8), a serotype thought to be of sub-Saharan origin. The most obvious mechanisms for BTV introduction, the import of infected hosts or the transport of infected Culicoides on airstreams, seemed unlikely. Therefore, the import of Culicoides along with or independently from the import of animals, plants or other ‘materials’ was considered as one of the possible explanations for the outbreak. In order to assess the likelihood of Culicoides being introduced via transport and trade networks, a quantitative risk assessment model has been constructed.

One of the objectives of Medreonet is to identify new serotypes of bluetongue (BT) in some countries of the Mediterranean Basin including Turkey. In May 2008, a cross-sectional study was con­ducted in cattle to investigate the presence of new serotypes in the provinces of Adana, Antalya, Hatay, Mersin, and Osmaniye. Cattle were the species selected since they had not been vac­cinated against BT and the vaccine did not interfere with the serological results. The village was established as the epidemio­logical unit. The sample size was calculated with the aim to detect at least 2% of positive villages and a within-village preva­lence of 30% (with 95% confidence level), resulting in a total of 1168 animals. A competitive enzyme-linked immunosorbent assay (cELISA) and an antigen capture ELISA (BTACE) were used to detect antibody and antigen, respectively. The presence of specific BT serotypes was confirmed by a specific polymerase chain reaction (PCR). To isolate BT virus, all the blood samples that were antigen positive were inoculated into embryonated chicken eggs and into cell cultures. Of the 1096 sera samples obtained, 994 (90.7%) were from dairy cattle (Holstein and crossbred Holstein), and only 102 (9.3%) were from beef breeds. A total of 352 (32.1%) sera samples were positive. Of the 140 villages sampled, 99 (71%) presented at least one positive animal, and the prevalence was 31%. The prevalence in dairy cattle was significantly (P = 0.0002) higher than in beef breeds (34 and 16%, respectively). Older animals presented a higher level of prevalence. Animals up to two years old had a prevalence of 24.3% (P < 0.05), whereas the preva­lence in adult animals was 52% (P < 0.05). Given that the last BT cases in Turkey were reported in August 2000 (serotypes 9 and 16), these data indicate that BT virus has been circulat­ing in the country in the last years. There were major differ­ences between provinces: 88% of the samples were positive in Osmaniye against only 14% in Antalya. These differences could be attributable to differences in vector densities, but they could also be related to host factors such as breed, density of cattle and small ruminant populations, and age of the animals (animals were older in some provinces than in others).

Potentially infected Culicoides may be accidentally carried in vehicles associated to the transport of people, animal, plants (cars, planes, boats...) coming from countries where bluetongue virus (BTV) is present. In order to estimate the risk of BTV trans­mission by the introduction of infected Culicoides by means of transport/commodities, a stochastic risk assessment model was constructed. The model was applied to estimate the risk to other countries by the introduction of one Culicoides infected with BTV serotype 1 from Spain. There is currently no data on the probability of Culicoides being transported by different means of transport/commodities. Therefore, the probability had to be estimated per vector. Four different steps were considered in the transmission pathway: probability of Culicoides infection, prob­ability of Culicoides surviving the extrinsic incubation period and the time to the next blood meal, probability of finding a new host, and probability of effective BTV transmission to host. The probability of BTV introduction by infected Culicoides was highly variable throughout the year, mainly as a consequence of differences in ambient temperatures. The maximum risk was reached in May with a mean probability of 1.7 x 10-8 (per vec­tor). The main limiting factors in this probability were the prob­ability of Culicoides infection, and the probability of Culicoides surviving the extrinsic incubation period and the time to the next blood meal. Given the low probability obtained for this pathway to be considered as important, the number of Culicoides trans­ported by these means should be very high.

In order to prevent the transmission of bluetongue virus (BTV) by semen, in case a semen collection or a storage centre is located within an endemic zone, the European Union established a ban on the movement of semen. However, there is a series of measures which may be applied to allow the exemption of semen from the exit ban. In order to assess the risk reduction achieved by some of these measures, a simulation model was constructed. In addition, the probability of introduction of BTV by importation of semen from a non-restricted area (exotic serotype) was also assessed.

Even though bluetongue virus (BTV) transmission is apparently interrupted during winter, bluetongue outbreaks often reappear in the next season (overwintering). Several mechanisms for BTV overwintering have been proposed, but to date their relative importance remains unclear. In order to assess the probability of BTV overwintering by horizontal transmission in vectors (long-lived Culicoides), ruminants (prolonged viraemia), or a combina­tion of both, a quantitative risk assessment model was developed. Furthermore, the model allowed the role played by the residual number of vectors present during winter to be examined, and the effect of a proportion of Culicoides living inside buildings (endophilic behaviour) to be explored. The model was then applied to a real scenario: overwintering in Germany between 2006 and 2007. The results showed that the limited number of vectors active during winter seemed to allow the transmission of BTV during this period and that this transmission was favoured by the endophilic behaviour of some Culicoides. Even though trans­mission was possible, the likelihood of BTV overwintering by horizontal transmission in vectors, ruminants or in both seemed however too low to explain the observed re-emergence of the disease. Therefore, other overwintering mechanisms that were not considered in the model are likely to have played a significant role in BTV overwintering in Germany between 2006 and 2007.

The objective of this study was to detect the presence of new serotypes of bluetongue (BT) circulating in Turkey. A cross-sec­tional study was conducted between March and May 2008 in the provinces of Adana, Mersin, Antalya, Osmaniye, and Hatay (Mediterranean region). The serosurvey was only performed in cattle. This species was not vaccinated and the presence of an­tibodies would indicate that the animal had been infected by field strains of BT virus. Only animals born after the outbreaks were sampled. The epidemiological unit was the village, which was the lowest level for which census data was available. Ran­dom sampling was carried out in 146 villages and eight sam­ples were collected in each village. A competitive enzyme-linked immunosorbent assay (cELISA) was used for detection of BT antibodies. Preliminary results of the study were presented. From a total of 1096 serum samples collected, 352 (32.1%) were positive to BT. The seroprevalence by province ranged from 15% in Antalya (45/257) to 88% in Osmaniye (77/88). In animals under two years old, the sero­prevalence was 25%, whereas in adult animals it was 52%. The differences in the seroprevalence detected between the five provinces could be attributed to the different density of vector, cattle and small ruminant populations. The high seroprevalence in unvaccinated cattle indicated that BT infection was wide­spread in the ruminant population of Turkey. The young animals presented a lower prevalence than the adults, suggesting that the adults had probably been exposed to the virus before the last two years, whereas the presence of positive seroconversion in young animals indicated that BT virus had been circulating in the two-year period.