Long-term dynamics of bluetongue virus in wild ruminants: relationship with outbreaks in livestock in Spain, 2006-2011

Diseases of Iberian ibex (Capra pyrenaica)

Iberian ibex (Capra pyrenaica) is an ecologically and economically relevant medium-sized emblematic mountain ungulate. Diseases participate in the population dynamics of the species as a regulating agent, but can also threaten the conservation and viability of vulnerable population units. Moreover, Iberian ibex can also be a carrier or even a reservoir of pathogens shared with domestic animals and/or humans, being therefore a concern for livestock and public health. The objective of this review is to compile the currently available knowledge on (1) diseases of Iberian ibex, presented according to their relevance on the health and demography of free-ranging populations; (2) diseases subjected to heath surveillance plans; (3) other diseases reported in the species; and (4) diseases with particular relevance in captive Iberian ibex populations. The systematic review of all the information on diseases affecting the species unveils unpublished reports, scientific communications in meetings, and scientific articles, allowing the first comprehensive compilation of Iberian ibex diseases. This review identifies the gaps in knowledge regarding pathogenesis, immune response, diagnostic methods, treatment, and management of diseases in Iberian ibex, providing a base for future research. Moreover, this challenges wildlife and livestock disease and wildlife population managers to assess the priorities and policies currently implemented in Iberian ibex health surveillance and monitoring and disease management.

A serological survey of pathogens associated with the respiratory and digestive system in the Polish European bison (Bison bonasus) population in 2017-2022

BACKGROUND

The European bison (Bison bonasus) is a near threatened species and requires health monitoring. The aim of the present study was to determine the prevalence of antibodies to pathogens known to cause respiratory and digestive illness in ruminants.

RESULTS

In the studied 328 European bison, the highest seroprevalence was observed for Bovine herpesvirus-1 (BoHV-1) (50.27%), Bovine Coronavirus (BCoV) (26.36%), and Bluetongue Virus (BTV) (12.83%). For Mycoplasma bovis strains and Bovine Viral Diarrhea Virus (BVDV), positive results were rare. Interestingly, a higher prevalence of BTV antibodies was noted in the northeastern populations and older animals.

CONCLUSIONS

Our findings indicate that the Polish European bison population appears to have considerable contact with BoHV-1; however, this does not appear to be of great significance, as clinical symptoms and post-mortem lesions are rarely noted in Polish European bison population. The high seroprevalence of BTV in the north-east of Poland is an ongoing trend, also noted in previous studies. It is possible that European bison may perpetuate the virus in this region. This is the first report of antibodies for BCoV in European bison.

Occurrence and limited zoonotic potential of Cryptosporidium spp., Giardia duodenalis, and Balantioides coli infections in free-ranging and farmed wild ungulates in Spain

Little information is currently available on the occurrence and molecular diversity of the enteric protozoan parasites Cryptosporidium spp., Giardia duodenalis, and Balantioides coli in wild ungulates and the role of these host species as potential sources of environmental contamination and consequent human infections. The presence of these three pathogens was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were retrospectively collected from free-ranging (n = 1058) and farmed (n = 324) wild ungulates from the five Spanish bioregions. Overall infection rates were 3.0% (42/1382; 95% CI: 2.1-3.9%) for Cryptosporidium spp., 5.4% (74/1382; 95% CI: 4.2-6.5%) for G. duodenalis, and 0.7% (9/1382; 95% CI: 0.3-1.2%) for B. coli. Cryptosporidium infection was detected in roe deer (7.5%), wild boar (7.0%) and red deer (1.5%), and G. duodenalis in southern chamois (12.9%), mouflon (10.0%), Iberian wild goat (9.0%), roe deer (7.5%), wild boar (5.6%), fallow deer (5.2%) and red deer (3.8%). Balantioides coli was only detected in wild boar (2.5%, 9/359). Sequence analyses revealed the presence of six distinct Cryptosporidium species: C. ryanae in red deer, roe deer, and wild boar; C. parvum in red deer and wild boar; C. ubiquitum in roe deer; C. scrofarum in wild boar; C. canis in roe deer; and C. suis in red deer. Zoonotic assemblages A and B were detected in wild boar and red deer, respectively. Ungulate-adapted assemblage E was identified in mouflon, red deer, and southern chamois. Attempts to genotype samples positive for B. coli failed. Sporadic infections by canine- or swine-adapted species may be indicative of potential cross-species transmission, although spurious infections cannot be ruled out. Molecular evidence gathered is consistent with parasite mild infections and limited environmental contamination with (oo)cysts. Free-ranging wild ungulate species would not presumably play a significant role as source of human infections by these pathogens. Wild ruminants do not seem to be susceptible hosts for B. coli.

Zoonotic Enterocytozoon bieneusi genotypes in free-ranging and farmed wild ungulates in Spain

Microsporidia comprises a diverse group of obligate, intracellular, and spore-forming parasites that infect a wide range of animals. Among them, Enterocytozoon bieneusi is the most frequently reported species in humans and other mammals and birds. Data on the epidemiology of E. bieneusi in wildlife is limited. Hence, E. bieneusi was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were collected from free-ranging (n = 1058) and farmed (n = 324) wild ungulates from five Spanish bioregions. The parasite was detected only in red deer (10.4%, 68/653) and wild boar (0.8%, 3/359). Enterocytozoon bieneusi infections were more common in farmed (19.4%, 63/324) than in wild (1.5%, 5/329) red deer. Eleven genotypes were identified in red deer, eight known (BEB6, BEB17, EbCar2, HLJD-V, MWC_d1, S5, Type IV, and Wildboar3) and three novel (DeerSpEb1, DeerSpEb2, and DeerSpEb3) genotypes. Mixed genotype infections were detected in 15.9% of farmed red deer. Two genotypes were identified in wild boar, a known (Wildboar3) and a novel (WildboarSpEb1) genotypes. All genotypes identified belonged to E. bieneusi zoonotic Groups 1 and 2. This study provides the most comprehensive epidemiological study of E. bieneusi in Spanish ungulates to date, representing the first evidence of the parasite in wild red deer populations worldwide. Spanish wild boars and red deer are reservoir of zoonotic genotypes of E. bieneusi and might play an underestimated role in the transmission of this microsporidian species to humans and other animals.

Risk-based serological survey of bluetongue and the first evidence of bluetongue virus serotype 26 circulation in Tunisia

BACKGROUND

Bluetongue (BT), a vector-borne disease of wild and domestic ruminants, is responsible for severe economic losses in flocks. To reduce this impact, a surveillance and control plan was implemented in Tunisia. However, the epidemiological situation of BT remains incompletely understood, especially for the circulating serotypes.

OBJECTIVE

The aim of this survey was to determine the seroprevalence, to identify the circulating serotypes and to identify the associated risk factors for bluetongue virus (BTV) circulation in Tunisia using risk-based sampling (RBS).

METHODS

A total of 3314 blood samples were randomly collected from 67 sectors using risk-based sampling and screened by competitive enzyme-linked immunosorbent assays (c-ELISAs). Out of the 1330 positive samples, 200 samples were analysed by serum neutralization test (SNT) to identify circulating BTV serotypes.

RESULTS

Of 3314 sera, 1330 were c-ELISA-positive (40.1%) for antibodies against the BTV structural protein VP7. The result of SNT showed the presence of BTV-1, BTV-2, BTV-3, BTV-4 and, for the first time in Tunisia, BTV-26. The logistic regression model revealed that older animals had nearly two times the odds of being infected with BTV compared to younger animals. Flocks with a history of BT were almost 1.5 times more likely to be at risk for contracting BTV infection. The flock size, housing indoors and intensive production system were significant protective factors.

CONCLUSIONS

High seroprevalence of BTV among sheep was highlighted in Tunisia. The neutralization test showed the presence of the following BTV serotypes: BTV-1, BTV-2, BTV-3, BTV-4 and, for the first time in Tunisia, BTV-26. Age, production system and flock size were important variables associated with BTV infection in sheep. This finding is crucial, as it will allow the adjustment of the BT control programme in Tunisia.

Survey of Culicoides-borne Bluetongue and Schmallenberg viruses at the wildlife-livestock interface in Doñana National Park (Spain)

A cross-sectional study was carried out to assess the circulation of bluetongue virus (BTV) and Schmallenberg virus (SBV) within the wild and domestic ungulate host community in Doñana National Park (southwestern Spain). A total of 440 animals, including 138 cattle, 102 red deer (Cervus elaphus), 101 fallow deer (Dama dama) and 99 wild boar (Sus scrofa) were sampled in 2015 during the seasonal peak of Culicoides spp. (summer-autumn). Serum and spleen samples were analysed to detect exposure (using commercial blocking ELISAs) and infection (by RT-PCR), respectively, to BTV and SBV. Cattle were not tested by BTV-bELISA because all were previously vaccinated against BTV serotypes 1 and 4. High BTV seroprevalences were found in red deer (97.0%) and fallow deer (64.7%). Antibodies against SBV were detected in 37.0% of cattle, 16.8% of red deer, 23.5% of fallow deer and 2.0% of wild boar. Thirty-eight of the 203 deer (18.7%; 17 red deer and 21 fallow deer) were co-exposed to both viral agents. BTV-4 RNA was confirmed in four red deer and two fallow deer. SBV RNA was found in two fallow deer. Co-infections were not detected. Our results indicate high exposure, widespread distribution, and active circulation of BTV and SBV in the ruminant community in the study area. We provide additional evidence for the potential role of wild cervids as reservoirs of these Culicoides-borne viruses in two different epidemiological scenarios: with vaccination (BTV) and without vaccination (SBV) of sympatric livestock. This study highlights the importance of wildlife surveillance, particularly of cervid species, for the proper execution of control programmes of Culicoides-borne diseases in extensively reared livestock. This article is protected by copyright. All rights reserved.

The Interplay between Bluetongue Virus Infections and Adaptive Immunity

Viral infections have long provided a platform to understand the workings of immunity. For instance, great strides towards defining basic immunology concepts, such as MHC restriction of antigen presentation or T-cell memory development and maintenance, have been achieved thanks to the study of lymphocytic choriomeningitis virus (LCMV) infections. These studies have also shaped our understanding of antiviral immunity, and in particular T-cell responses. In the present review, we discuss how bluetongue virus (BTV), an economically important arbovirus from the Reoviridae family that affects ruminants, affects adaptive immunity in the natural hosts. During the initial stages of infection, BTV triggers leucopenia in the hosts. The host then mounts an adaptive immune response that controls the disease. In this work, we discuss how BTV triggers CD8⁺ T-cell expansion and neutralizing antibody responses, yet in some individuals viremia remains detectable after these adaptive immune mechanisms are active. We present some unpublished data showing that BTV infection also affects other T cell populations such as CD4⁺ T-cells or γδ T-cells, as well as B-cell numbers in the periphery. This review also discusses how BTV evades these adaptive immune mechanisms so that it can be transmitted back to the arthropod host. Understanding the interaction of BTV with immunity could ultimately define the correlates of protection with immune mechanisms that would improve our knowledge of ruminant immunology.

Long-term determinants of the seroprevalence of the bluetongue virus in deer species in southern Spain

Bluetongue is a vector-borne disease affecting domestic and wild ruminants, with a major socioeconomic impact. Endemic circulation of the bluetongue virus serotype 4 (BTV-4) and BTV-1 have occurred in Spain since 2004 and 2007, respectively. However, epidemiological studies have seldom been approached from a long-term perspective in wild ruminants. A total of 881 deer (red deer and fallow deer) were necropsied from 2005 to 2018 as part of the DNP health-monitoring program. Serum samples were tested for antibodies against BTV with the aims of assessing the temporal trend and to evaluate the modulating factors: individual, populational, environmental, and stochastic. Red deer displayed statistically significant higher seroprevalences of BTV (SBT; 78.6 ± 3.8%) than fallow deer (53.1 ± 4.7%). The detection of BTV-1 and BTV-4 by the serum neutralization test in calves suggested the circulation of both serotypes over the study period. For red deer, wet years together with high densities could provide suitable conditions for vector borne BTV transmission. Moreover, proximity to high suitability habitat for Culicoides, permanent pasturelands, was associated with higher SBT. The differences in the ecology and behaviour of deer species influencing the exposure to the vectors could determine the differences found in the SBT patterns. This study evidences the role that deer species may play in the maintenance of BTV, however, elucidating the epidemiological role of host in different contexts as well as the consequences of climate change on the competent vector populations and its potential effect on the dynamics of BTV infection in hosts communities deserve further research.

Monitoring of bluetongue virus in zoo animals in Spain, 2007-2019

Bluetongue (BT) is an emerging and re-emerging communicable vector-borne disease of animal health concern. A serosurvey was performed to assess exposure to BT virus (BTV) in zoo animals in Spain and to determine the dynamics of seropositivity in longitudinally sampled individuals during the study period. Serum samples were collected from 241 zoo animals belonging to 71 different species in five urban zoos (A-E) in Spain between 2007 and 2019. Twenty-four of these animals were longitudinally surveyed at three of the sampled zoos (zoos B, C and E) during the study period. Anti-BTV antibodies were found in 46 (19.1%; 95% CI: 14.1-24.1) of the 241 captive animals analysed by commercial ELISA. A virus neutralization test confirmed specific antibodies against BTV-1 and BTV-4 in 25 (10.7%; 95% CI: 6.7-14.6) and five (3.0%; 95% CI: 0.3-4.0) animals, respectively. Two of the 24 longitudinally sampled individuals (one African elephant (Loxodanta africana) and one aoudad (Ammotragus lervia)) showed anti-BTV antibodies at all samplings, whereas seroconversions were detected in one mouflon (Ovis aries musimon) in 2016, and one Asian elephant (Elephas maximus) in 2019. To the best of the authors' knowledge, this is the first large-scale survey on BTV conducted in both artiodactyl and non-artiodactyl zoo species worldwide. The results confirm BTV exposure in urban zoo parks in Spain, which could be of animal health and conservation concern. Circulation of BTV was detected in yearling animals in years when there were no reports of BTV outbreaks in livestock. Surveillance in artiodactyl and non-artiodactyl zoo species could be a valuable tool for epidemiological monitoring of BTV.

Demography reveals populational expansion of a recently extinct Iberian ungulate

Reconstructing the demographic history of endangered taxa is paramount to predict future fluctuations and disentangle the contributing factors. Extinct taxa or populations might also provide key insights in this respect by means of the DNA extracted from museum specimens. Nevertheless, the degraded status of biological material and the limited number of records may pose some constraints. For this reason, identifying all available sources, including private and public biological collections, is a crucial step forward. In this study, we reconstructed the demographic history based on cytochrome-b sequence data of the Pyrenean ibex (Capra pyrenaica pyrenaica), a charismatic taxon of the European wildlife that became extinct in the year 2000. Moreover, we built a database of the museum specimens available in public biological collections worldwide and genotyped a privately owned 140-year-old trophy from the Spanish Pyrenees to confirm its origin. We found that the population of the Pyrenean ibex underwent a recent expansion approximately 20,000 years ago, after which trophy hunting and epizootics triggered a relentless population decline. Our interpretations, based on the genetic information currently available in public repositories, provide a solid basis for more exhaustive analyses relying on all the new sources identified. In particular, the adoption of a genome-wide approach appears a fundamental prerequisite to disentangle the multiple contributing factors associated with low genetic diversity, including inbreeding depression, acting as extinction drivers.

Bluetongue virus serotype 12 enters Australia - a further incursion of novel western lineage genome segments

Bluetongue virus (BTV) is an arbovirus (genus: Orbivirus) that occurs worldwide. It infects domestic and wild ruminant species and can cause disease in livestock, producing high economic impact. Recently, it gained extra prominence throughout Europe, with disease occurring in regions traditionally free of BTV. BTV enters Australia from Southeast Asia via wind-borne infected Culicoides spp. The first Australian isolation was 1975 (BTV-20) and further serotypes were isolated between 1979-86 (BTV-1, -3, -9, -15, -16, -21, -23). Despite increased, more sensitive, monitoring, no more were detected in over two decades, implying a stable BTV episystem of eastern ancestry. Isolations of BTV-2, -7 and -5 then occurred between 2007-15, with the latter two possessing genome segments with high sequence identity to western isolates. We report on the first isolation and genomic characterization of BTV-12, which revealed that three more novel western topotype gene segments have entered northern Australia.

Identifying Spanish Areas at More Risk of Monthly BTV Transmission with a Basic Reproduction Number Approach

Bluetongue virus (BTV) causes a disease that is endemic in Spain and its two major biological vector species, C. imicola and the Obsoletus complex species, differ greatly in their ecology and distribution. Understanding the seasonality of BTV transmission in risk areas is key to improving surveillance and control programs, as well as to better understand the pathogen transmission networks between wildlife and livestock. Here, monthly risk transmission maps were generated using risk categories based on well-known BTV R0 equations and predicted abundances of the two most relevant vectors in Spain. Previously, Culicoides spp. predicted abundances in mainland Spain and the Balearic Islands were obtained using remote sensing data and random forest machine learning algorithm. Risk transmission maps were externally assessed with the estimated date of infection of BTV-1 and BTV-4 historical outbreaks. Our results highlight the differences in risk transmission during April-October, June-August being the period with higher R0 values. Likewise, a natural barrier has been identified between northern and central-southern areas at risk that may hamper BTV spread between them. Our results can be relevant to implement risk-based interventions for the prevention, control and surveillance of BTV and other diseases shared between livestock and wildlife host populations.

Distribution of Pestivirus exposure in wild ruminants in Spain

A large-scale study was carried out to determine the prevalence of antibodies against Pestivirus species in wild ruminants and describe their spatial variation in mainland Spain. Serum samples of 1,874 wild ruminants from different regions of this country were collected between the years 2000 and 2017. A total of 6.6% (123/1,874) animals showed antibodies against Pestivirus by both blocking ELISA (bELISA) and virus neutralization tests (VNT). The prevalence of antibodies against pestiviruses was different both among species and regions. Seroprevalence by species was 30.0% (75/250) in Southern chamois (Rupicapra pyrenaica), 7.0% (25/357) in fallow deer (Dama dama), 2.5% (10/401) in red deer (Cervus elaphus), 2.4% (8/330) in Iberian wild goat (Capra pyrenaica), 1.1% (4/369) in roe deer (Capreolus capreolus) and 0.8% (1/130) in mouflon (Ovis aries musimon), not detecting seropositivity (0/37) in Barbary sheep (Ammotragus lervia). The results confirm that exposure to pestiviruses was detected throughout mainland Spain, with significantly higher seroprevalence in Northern regions associated with the presence of Southern chamois. This indicates an endemic circulation of pestiviruses in Southern chamois and a limited circulation of these viruses in the remaining wild ruminant species during the last two decades, thus suggesting that non-chamois species are not true Pestivirus reservoirs in Spain. Nonetheless, the high spatial spread of these viruses points out that new epidemic outbreaks in naïve wild ruminant populations or transmission to livestock may occur, evidencing the usefulness of monitoring pestiviruses in wild ruminants, especially at the wildlife-livestock interface.

Spatiotemporal monitoring of selected pathogens in Iberian ibex (Capra pyrenaica)

An epidemiological surveillance programme was carried out to assess exposure and spatiotemporal patterns of selected pathogens (Brucella spp., Mycobacterium avium subsp. paratuberculosis (MAP), Mycoplasma agalactiae, Pestivirus and bluetongue virus (BTV)) in Iberian ibex (Capra pyrenaica) from Andalusia (southern Spain), the region with the largest population of this species. A total of 602 animals in five distribution areas were sampled during 2010-2012 (P1) and 2013-2015 (P2). The Rose Bengal test (RBT) and complement fixation test (CFT) were used in parallel to detect anti-Brucella spp. antibodies. Commercial ELISAs were used to test for antibodies against the other selected pathogens. Sera positive for BTV and Pestivirus by ELISA were tested by serum neutralization test (SNT) to identify circulating serotypes/genotypes. The overall seroprevalences were as follows: 0.4% for Brucella spp. (2/549; CI 95%: 0.1-1.3) (14/555 positive by RBT; 2/564 by CFT), 0.5% for MAP (3/564; CI 95%: 0.1-1.5), 5.7% for M. agalactiae (30/529; CI 95%: 3.9-8.0), 11.1% for Pestivirus (58/525; CI 95%: 8.5-14.1) and 3.3% for BTV (18/538; CI 95%: 2.0-5.2). Significantly higher seropositivity to both M. agalactiae and BTV was observed in P1 compared with P2. Spatiotemporal clusters of high seroprevalence were also found for M. agalactiae in four of the five sampling areas in 2010, and for BTV in one of five areas in 2012. Specific antibodies against BTV-4, BDV-4 and BVDV-1 were confirmed by SNT. Our results indicate that the Iberian ibex may be considered spillover hosts of Brucella spp. and MAP rather than true reservoirs. The prevalence of antibodies against M. agalactiae and BTV suggests spatiotemporal variation in the circulation of these pathogens, while Pestivirus has a moderately endemic circulation in Iberian ibex populations. Our study highlights the importance of long-term surveillance for a better understanding of the spatiotemporal distribution of shared infectious diseases and providing valuable information to improve control measures at the wildlife-livestock interface.

Evaluation of Bluetongue Virus (BTV) Antibodies for the Immunohistochemical Detection of BTV and Other Orbiviruses

The detection of bluetongue virus (BTV) antigens in formalin-fixed tissues has been challenging; therefore, only a limited number of studies on suitable immunohistochemical approaches have been reported. This study details the successful application of antibodies for the immunohistochemical detection of BTV in BSR variant baby hamster kidney cells (BHK-BSR) and infected sheep lungs that were formalin-fixed and paraffin-embedded (FFPE). BTV reactive antibodies raised against non-structural (NS) proteins 1, 2, and 3/3a and viral structural protein 7 (VP7) were first evaluated on FFPE BTV-infected cell pellets for their ability to detect BTV serotype 1 (BTV-1). Antibodies that were successful in immunolabelling BTV-1 infected cell pellets were further tested, using similar methods, to determine their broader immunoreactivity against a diverse range of BTV and other orbiviruses. Antibodies specific for NS1, NS2, and NS3/3a were able to detect all BTV isolates tested, and the VP7 antibody cross-reacted with all BTV isolates, except BTV-15. The NS1 antibodies were BTV serogroup-specific, while the NS2, NS3/3a, and VP7 antibodies demonstrated immunologic cross-reactivity to related orbiviruses. These antibodies also detected viral antigens in BTV-3 infected sheep lung. This study demonstrates the utility of FFPE-infected cell pellets for the development and validation of BTV immunohistochemistry.

Re-emergence of bluetongue virus serotype 4 in Iberian ibex (Capra pyrenaica) and sympatric livestock in Spain, 2018-2019

Between early October and mid-December 2018, mortalities were detected in Iberian ibex (Capra pyrenaica) populations in southern Spain. In the same region and period, bluetongue virus (BTV) circulation was also reported in sentinel and clinically affected domestic ruminant herds. Molecular analyses confirmed BTV serotype 4 (BTV-4) infection in eight Iberian ibexes from six hunting areas, and in 46 domestic ruminants from seven herds in close proximity to affected hunting estates. Histopathological analyses revealed vascular changes in several organs, pneumonia, lymphoid depletion, inflammatory mononuclear cell infiltrate and fibrosis as the most frequently observed lesions in the affected Iberian ibexes. Epidemiological and laboratory results indicate that BTV-4 was the main aetiological agent involved in outbreaks detected in Iberian ibex populations during the study period. Sequence analyses indicated that the BTV-4 strain detected in Iberian ibex had high homology (99.4%-100%) with strains isolated in livestock during the same period, and with previous isolates (≥98.9%) from Spain and Mediterranean Basin countries. Further studies are warranted to determine the impact of BTV-4 on the health status of Iberian ibex populations after the outbreaks. The inclusion of this species in the surveillance programme may be useful for early detection of BTV, especially in epidemiological scenarios at the wildlife-livestock interface.

Serosurveillance of Schmallenberg virus in wild ruminants in Spain

Schmallenberg disease (SBD) is an emerging vector-borne disease that affects domestic and wild ruminants. A long-term serosurvey was conducted to assess exposure to Schmallenberg virus (SBV) in all the wild ruminant species present in mainland Spain. Between 2010 and 2016, sera from 1,216 animals were tested for antibodies against SBV using a commercial blocking ELISA. The overall prevalence of antibodies was 27.1% (95%CI: 24.7-29.7). Statistically significant differences among species were observed, with significantly higher seropositivity found in fallow deer (Dama dama) (45.6%; 99/217), red deer (Cervus elaphus) (31.6%; 97/307) and mouflon (Ovis aries musimon) (28.0%; 33/118) compared to Barbary sheep (Ammotragus lervia) (22.2%; 8/36), Iberian wild goat (Capra pyrenaica) (19.9%; 49/246), roe deer (Capreolus capreolus) (17.5%; 34/194) and Southern chamois (Rupicapra pyrenaica) (10.2%; 10/98). Seropositive animals were detected in 81.4% (57/70; 95%CI: 70.8-88.8) of the sampled populations. SBV seroprevalence ranged from 18.8% (48/256) in bioregion (BR)2 (north-central, Mediterranean) to 32.3% (31/96) in BR1 (northeastern or Atlantic, Eurosiberian). Anti-SBV antibodies were not found before 2012, when the first outbreak of SBD was reported in Spain. In contrast, seropositivity was detected uninterruptedly during the period 2012-2016 and anti-SBV antibodies were found in yearling animals in each of these years. Our results provide evidence of widespread endemic circulation of SBV among wild ruminant populations in mainland Spain in recent years. Surveillance in these species could be a useful tool for monitoring SBV in Europe, particularly in areas where wild ruminants share habitats with livestock.

Large-scale seroprevalence and risk factors associated with Bluetongue virus in Iran

Bluetongue virus (BTV) remains as an economically major concern in the world. Seroprevalence and potential risk factors of BTV were assessed in a cross-sectional study at both the herd and animal levels in Iran. A total of 73 Epidemiologic Units (E.Unit), defined as a herd, flock or village including animals with equal chance of exposure to infectious agents, were randomly selected. Serum samples from all animals (n = 34,575) within the E.Units were collected and tested for BTV sero-group antibodies by using commercially competitive ELISA test. Using cluster analysis, 90.41 % (95 %, CI: 80.85 %-95.47 %) of the E.Units and 56.13 % (95 % CI: 55.61 %-56.66 %) of the tested animals were detected seropositive against BTV. A seroprevalence rate of 57.59 % (95 % CI: 48.01 %-66.63 %), 65.65 % (95 % CI: 59.10 %-73.74 %) and 27.63 % (95 % CI: 14.40 %-46.43 %) was estimated for sheep, goats and cattle, respectively. At E.Unit (herd) level, density was identified as a great risk factor for the infection (r² = 0.891; P = 0.000), and particularly density of cattle significantly correlated with BTV infection within the E.Units (r² = 0.247; P = 0.019). Using multilevel logistic regression, adjusted odds ratios (ORs) were estimated at individual level. A significantly less risk of BTV infection was evaluated for cattle than for sheep (OR = 0.42, 95 % CI: 0.38-0.47, P < 0.001), while no significant difference was observed between sheep and goat (OR = 1.03, 95 % CI: 0.97-1.10, P = 0.345). Animals over 2 years and between 6 months and 2 years expressed 2.22 (OR = 2.22, 95 % CI: 1.96-2.52, P < 0.001) and 2.18 (OR = 2.18, 95 % CI: 1.92-2.49, P < 0.001) times higher chance for the infection than animals under 6 months. Males were at significantly less risk of the infection than females (OR=0.68, 95 % CI: 0.63-0.74, P < 0.001). Animals kept in industrial farming systems displayed 0.46 (OR=0.46, 95 % CI: 032-0.66, P < 0.001) times less chance than animals kept in traditional farming system for BTV, while animals lived in semi-industrial farming system were found to be at 2.97 (OR=2.97, 95 % CI: 2.41-3.66, P < 0.001) times higher chance for BTV than animals lived in traditional farming system. Furthermore, seropositive animals exhibited a high amount of antibodies against BTV (s) suggesting that viral exposure may have frequently occurred during their lifetimes. This large - scale study yielded information on epidemiology of BTV in Iran that is prerequisite for further research, and also for evaluation of any cost-benefit control measure to be established in an enzootic zone of the virus.

Culicoides species composition and molecular identification of host blood meals at two zoos in the UK

BACKGROUND

Culicoides biting midges are biological vectors of arboviruses including bluetongue virus (BTV), Schmallenberg virus (SBV) and African horse sickness virus (AHSV). Zoos are home to a wide range of 'at risk' exotic and native species of animals. These animals have a high value both in monetary terms, conservation significance and breeding potential. To understand the risk these viruses pose to zoo animals, it is necessary to characterise the Culicoides fauna at zoos and determine which potential vector species are feeding on which hosts.

METHODS

Light-suction traps were used at two UK zoos: the Zoological Society of London (ZSL) London Zoo (LZ) and ZSL Whipsnade Zoo (WZ). Traps were run one night each week from June 2014 to June 2015. Culicoides were morphologically identified to the species level and any blood-fed Culicoides were processed for blood-meal analysis. DNA from blood meals was extracted and amplified using previously published primers. Sequencing was then carried out to determine the host species.

RESULTS

A total of 11,648 Culicoides were trapped and identified (n = 5880 from ZSL WZ; n = 5768 from ZSL LZ), constituting 25 different species. The six putative vectors of BTV, SBV and AHSV in northern Europe were found at both zoos and made up the majority of the total catch (n = 10,701). A total of 31 host sequences were obtained from blood-fed Culicoides. Culicoides obsoletus/C. scoticus, Culicoides dewulfi, Culicoides parroti and Culicoides punctatus were found to be biting a wide range of mammals including Bactrian camels, Indian rhinoceros, Asian elephants and humans, with Culicoides obsoletus/C. scoticus also biting Darwin's rhea. The bird-biting species, Culicoides achrayi, was found to be feeding on blackbirds, blue tits, magpies and carrion crows.

CONCLUSIONS

To our knowledge, this is the first study to directly confirm blood-feeding of Culicoides on exotic zoo animals in the UK and shows that they are able to utilise a wide range of exotic as well as native host species. Due to the susceptibility of some zoo animals to Culicoides-borne arboviruses, this study demonstrates that in the event of an outbreak of one of these viruses in the UK, preventative and mitigating measures would need to be taken.

Evaluation of two enzyme-linked immunosorbent assays for diagnosis of bluetongue virus in wild ruminants

Bluetongue (BT) is a reportable re-emerging vector-borne disease of animal health concern. Enzyme-linked immunosorbent assays (ELISA) are frequently used in BT surveillance programs in domestic ruminants, but their diagnostic accuracy has not been evaluated for wild ruminants, which can play an important role as natural reservoirs of bluetongue virus (BTV). The aim of this study was to assess two commercial ELISAs for BT diagnosis in wild ruminants using control sera of known BTV infection status and field samples. When control sera were tested, the double recognition ELISA (DR-ELISA) showed 100 % sensitivity (Se) and specificity (Sp), while the competitive ELISA (C-ELISA) had 86.4 % Se and 97.1 % Sp. Using field samples, the selected latent-class analysis model showed 95.7 % Se and 85.9 % Sp for DR-ELISA, 58.2 % Se and 95.8 % Sp for C-ELISA and 84.2 % Se for the serum neutralization test (SNT). Our results indicate that the DR-ELISA may be a useful diagnostic method to assess BTV circulation in endemic areas, while the C-ELISA should be selected when free-areas are surveyed. The discrepancy between control and field samples point out that the inclusion of field samples is required to assess the accuracy of commercial ELISAs for the serological diagnosis of BTV in wild ruminants.

Method validation, reference values, and characterization of acute-phase protein responses to experimentally induced inflammation and bluetongue virus infection in the Iberian ibex

BACKGROUND

Acute phase protein (APP) concentrations can change due to inflammation and be used to monitor disease in the Iberian ibex (Capra pyrenaica).

OBJECTIVES

This study aimed to validate Haptoglobin (Hp) and serum amyloid A (SAA) analytes, establish reference values, and characterize Hp and SAA responses in the Iberian ibex after experimentally induced inflammation and experimental bluetongue virus (BTV) infection.

METHODS

Sera from 40 free-ranging box-trapped ibexes were used to establish Hp and SAA reference values. Six healthy ibexes were subcutaneously injected with 5 mL of turpentine, then, blood samples were taken, and clinical evaluations were performed on days 0, 1, 2, 3, 4, 7, and 14 postinjection. Another seven ibexes were challenged with BTV. Serum Hp and SAA concentrations were quantified using commercial assays following the manufacturer's instructions.

RESULTS

Intra-assay precision and linearity were acceptable for both Hp and SAA. Intra-assay variation for high and low concentration of Hp and SAA were 9.74% and 17.31% and 16.49% and 12.89%, respectively. Inter-assay variation was higher for the low APP concentrations. Reference values for the healthy Iberian ibexes were (median, minimum, and maximum values) 0.2 (0.12-0.64) g/L for Hp and 4.74 (0.05-29.54) mg/L for SAA. Both Hp and SAA acted as a moderate and a major APP, respectively, and each could distinguish animals with turpentine-induced inflammation from those without. Hp and SAA did not change in asymptomatic BTV-infected animals.

CONCLUSION

This study validated Hp and SAA analytes and provided basal reference values for these analytes in the Iberian ibex. Both APPs were able to discriminate between healthy and diseased Iberian ibexes animals during turpentine-induced inflammatory processes.

Red deer (Cervus elaphus) Did Not Play the Role of Maintenance Host for Bluetongue Virus in France: The Burden of Proof by Long-Term Wildlife Monitoring and Culicoides Snapshots

Bluetongue virus (BTV) is a Culicoides-borne pathogen infecting both domestic and wild ruminants. In Europe, the Red Deer (Cervus elaphus) (RD) is considered a potential BTV reservoir, but persistent sylvatic cycle has not yet been demonstrated. In this paper, we explored the dynamics of BTV1 and BTV8 serotypes in the RD in France, and the potential role of that species in the re-emergence of BTV8 in livestock by 2015 (i.e., 5 years after the former last domestic cases). We performed 8 years of longitudinal monitoring (2008–2015) among 15 RD populations and 3065 individuals. We compared Culicoides communities and feeding habits within domestic and wild animal environments (51,380 samples). Culicoides diversity (>30 species) varied between them, but bridge-species able to feed on both wild and domestic hosts were abundant in both situations. Despite the presence of competent vectors in natural environments, BTV1 and BTV8 strains never spread in RD along the green corridors out of the domestic outbreak range. Decreasing antibody trends with no PCR results two years after the last domestic outbreak suggests that seropositive young RD were not recently infected but carried maternal antibodies. We conclude that RD did not play a role in spreading or maintaining BTV in France.

Preliminary serological and molecular investigation of selected viral pathogens in Croatian cervid species

A total of 131 blood samples and 175 spleen samples were collected from three cervid species: roe deer (Capreolus capreolus), red deer (Cervus elaphus) and fallow deer (Dama dama) inhabiting the continental part of Croatia. Serum samples were tested for antibodies against bovine herpesvirus 1, parainfluenza-3 virus, bluetongue virus, bovine respiratory syncytial virus, hepatitis E virus, bovine viral diarrhoea virus and enzootic bovine leukosis virus. The tested sera were negative for bovine viral diarrhoea virus, enzootic bovine leukosis virus, bluetongue virus, bovine respiratory syncytial virus and hepatitis E virus antybodies. The antibody prevalence in roe deer and red deer samples was 21.11% for bovine herpesvirus 1 and 75.55% for parainfluenza-3 virus. Sera from bovine herpesvirus 1 positive animals were subsequenty tested with comparative virus neutralization test and bovine herpesvirus 1 neutralising antibodies were found in 18 (out of 19) sera. In fallow deer, no antibodies against any of the viral pathogens were detected. All spleen samples tested for bovine viral diarrhoea virus and enzootic bovine leukosis virus came back negative, except for one red deer spleen sample found to be weakly diarrhoea virus-positive. Our findings provide the first information on the exposure of Croatia-inhabiting cervid species to viral pathogens, and could serve as valuable baseline data for future investigations regarding deer exposure to various pathogens and the distribution of diseases shared between wildlife and livestock. As of now, the epidemiology of these viruses in the Croatian cervid population has been only poorly understood, so that further research is recommended.

Analysis of spatial dynamic of epizootic process of bluetongue and its risk factors

AIM

The study was undertaken to find out the spatial dynamic occurrence and patterns of the global spread of bluetongue (BT) disease for the period from 1996 to 2016, as well as the assessment of the risk of occurrence and its spread in 2017-2018.

MATERIALS AND METHODS

Outbreaks (serum samples were collected from clinically healthy as well as suspected animals in infected points) were confirmed and reported officially by veterinary departments which represent different geographical regions in the world to World Organization for Animal Health. These reports explained that ELISA and polymerase chain reaction were used to identify the BT disease, taking in the account number of infected, dead animals, and focus of BT infection in all susceptible animals from 1996 to 2016. Once conventional statistical population was defined (an observational study), we had classified data as well as possible to answer to our aim, using descriptive statistics methods, including the test of the relationship between different epizootiological indicators.

RESULTS

The spatial dynamic study of BT's occurrence and its spread in the world over the two past decades was presented by different epizootic indicators. The given analysis includes assessment and measurement of risk factors. It was built too, regression models, and allowed to put different forecasts on the different epizootic indicators in the years 2017-2018 by the extrapolation method. We had also determined that, in 2017, BT continues to spread with the total expectancy of 3.4 focus of infection (number of diseased animals in a single unfavorable point) and mortality of about 26 %; these rates tend to decrease in 2018. At abused points by BT, up to 78.4% of animals are mixed (more than one type) and in 21.6% - uniform. By this way, the relative risk of the incidence of appearance-abused points in mixed households has 3.64, which might be considered higher for the BT dissemination. Moreover, between the enzootic index and other epizootiological indicators had revealed an inverse correlation, i.e., to an increase in the level of enzootic index among the cattle population would be formed population less sensitive to BT. Cluster analysis was done, which had demonstrated the zoning of risk levels in the world and the occurrence of the disease intensity in the period 1996-2016 years. Then, assess connection degree of the dynamic of BT tension with geographical and socioeconomic conditions background 0.66 and 0.68, respectively.

CONCLUSION

It is important to define a variety of BT risk factors and assess their influence on BT occurrence. However, the most important is to define the overlapping coinfluence between them that cause serious losses. To have an out of BT territory needs to make an emphasis of co-influence of risk factors on this zone. Was predicted a continue hits of disease in the next year with weight moderation through one year. Far from statists, to assess the given forecast may have a serious variety, taken in account problems of actual climate change in the world.

Monitoring of Schmallenberg virus in Spanish wild artiodactyls, 2006-2015

Schmallenberg disease is an emerging disease that affects domestic and wild ruminants in Europe. An epidemiological survey was carried out to assess exposure to Schmallenberg virus (SBV) in wild artiodactyls in Spain between 2006 and 2015. A total of 1751 sera from wild artiodactyls, including 1066 red deer, 304 fallow deer, 192 mouflon, 109 wild boar, 49 roe deer and 31 Spanish ibex were tested for antibodies against SBV by ELISA and confirmed by virus neutralization test. SBV was not detected between the 2006/2007 and the 2010/2011 hunting seasons. Overall seroprevalence (including samples collected between the 2011/2012 and 2014/2015 hunting seasons) was 14.6% (160/1099; 95%CI: 12.7–16.6). Mean SBV seroprevalence was 13.3±2.6% in red deer, 23.9±4.2% in fallow deer, 16.4±6.1% in mouflon and 2.8±3.1% in wild boar. No antibodies against SBV were found in roe deer or Spanish ibex. The presence of SBV RNA was confirmed in three of 255 (1.2%) spleen samples from wild ruminants analysed by rRT-PCR. In a multivariate mixed-effects logistic regression model, the main risk factors associated with SBV seroprevalence were: species (fallow deer, red deer and mouflon), age (adults) and interactions between hunting areas of more than 1000 hectares and hunting season (2012/2013, 2013/2014 and 2014/2015). The hypothesis of endemic circulation of SBV in the last few years is supported by the detection of SBV RNA in animals sampled in 2011 and 2015, as well as antibodies detected at low level in juveniles in 2012, 2013 and 2014. The results indicate that SBV circulated in wild ruminant populations in Spain during the same period when the virus was first reported in northern Europe, and at least five months before the first case was officially reported in livestock in Spain.

Spatial-temporal Trends and Factors Associated with the Bluetongue Virus Seropositivity in Large Game Hunting Areas from Southern Spain

An epidemiological study was carried out to determine the spatial-temporal trends and risk factors potentially involved in the seropositivity to bluetongue virus (BTV) in hunting areas with presence of red deer (Cervus elaphus). A total of 60 of 98 (61.2%; CI95% : 51.6-70.9) hunting areas sampled presented at least one seropositive red deer. Antibodies against BTV were detected in juvenile animals during the hunting seasons 2007/2008 to 2013/2014 in 15 of 98 (15.3%) hunting areas, which indicates an uninterrupted circulation of BTV in this period. A multivariate logistic regression model showed that the red deer density at hunting area level (>22 individuals/km(2) ), the annual abundance of Culicoides imicola (>1.4 mosquitoes/sampling) and the goat density at municipality level (>24.1 individuals/km(2) ) were factors significantly associated with BTV seropositivity in hunting areas. Control measures against BTV in the studied area include vaccination programmes in wild and domestic ruminants, movement control in areas with high densities and abundance of red deer and C. imicola, respectively. Considering the potential risk of BTV re-emergence, red deer should be included in the BT surveillance programmes in regions where these species share habitats with livestock.

Wild ungulates as sentinel of BTV-8 infection in piedmont areas

Bluetongue caused by the genotype 8 virus (BTV-8) appeared for the first time in BTV free areas in northern Italy in 2008. The presence of domestic animals outbreaks, abundant wild ungulates populations, and ongoing regional BTV control plans, made this area interesting to evaluate the role of wild ruminants in BTV-8 epidemiology. We analyzed spleen samples from hunted red deer (Cervus elaphus), roe deer (Capreolus capreolus) and Alpine chamois (Rupicapra rupicapra) by quantitative RT-PCR. Samples were collected from 2008 to 2011 in two provinces of Piedmont region. BTV-8 was detected in all ungulate species, confirming their receptivity to the infection. However, the viral load in the positive specimens was low, and decreased from 2008 to 2011. These results, together with the extinction of the epidemic following a regional livestock vaccination campaign, lead to hypothesize that wild ungulates were an epiphenomenon and they had not an important role in the domestic transmission cycle of BTV-8 in this area. In spite of this, wild ruminants appear to be good sentinels of BTV circulation and their monitoring could be useful for surveillance in piedmont areas.