Surveillance of Culicoides (Diptera: Ceratopogonidae) biting midges was carried out between 2001 and 2003, at 119 sites within a 50 x 50-km grid distributed across Bulgaria, using light trap collections around the time of peak adult midge abundance. Sentinel and ad hoc serum surveillance of hosts susceptible to bluetongue infection was carried out at around 300 sites between 1999 and 2003. Following the initial incursion of bluetongue virus 9 (BTV-9) into Bourgas province in 1999, affecting 85 villages along the southern border, a further 76 villages were affected along the western border in 2001, with outbreaks extending as far north as 43.6 degrees N. The BTV-9 strain in circulation was found to have a low pathogenicity for Bulgarian sheep populations, with less than 2% of susceptible individuals becoming sick and seroconversions detected up to 30 km from recorded outbreaks in the south. The major Old World vector Culicoides imicola Kieffer was not detected among over 70,000 Culicoides identified in summer collections, suggesting that BTV-9 transmission in Bulgaria was primarily carried out by indigenous European vectors. The most likely candidates, the Palaearctic species complexes - the Culicoides obsoletus Meigen and C. pulicaris L. complexes - were widespread and abundant across the whole country. The C. obsoletus complex represented 75% of all individuals trapped in summer and occurred in high catch sizes (up to 15,000 individuals per night) but was not found across all outbreak sites, indicating that both Palearctic complexes probably played a role in transmission. Within the C. pulicaris complex, only C. pulicaris s.s., C. punctatus Meigen and C. newsteadi Austen were sufficiently abundant and prevalent to have been widely involved in transmission, whilst within the C. obsoletus complex most trapped males were C. obsoletus s.s. Adult vectors were found to be largely absent from sites in west Bulgaria for a period of at least 3 months over winter, which, taken along with the spatiotemporal pattern of outbreaks in the region between years, indicates the virus may be overwintering here by an alternative mechanism - either by covert persistence in the vertebrate host or possibly by persistence in larval stages of the vector.

Summary 1.The spread of vector-borne diseases into new areas, commonly attributed to environmental change or increased trade and travel, could be exacerbated if novel vector species in newly invaded areas spread infection beyond the range of traditional vectors. 2. By analysing the differential degree of overlap between the environmental envelopes for bluetongue, a devastating livestock disease, and its traditional (Afro-Asian) and potential new (Palearctic) midge vectors, we have implicated the latter in the recent dramatic northward spread of this disease into Europe. 3. The traditional vector of bluetongue virus, the Afro-Asian midge Culicoides imicola , was found to occur in warm (annual mean 12-20 ° C), thermally stable locations that were dry in summer (< 400 mm precipitation). The Palearctic C. obsoletus and C. pulicaris complexes were both found to occur in cooler (down to 7 ° C annual mean), thermally more variable and wetter (up to 700 mm summer precipitation) locations. 4. Of 501 recorded outbreaks from the 1998-2004 bluetongue epidemic in southern Europe, 40% fall outside the climate envelope of C. imicola , but within the species' envelopes of the C. obsoletus and C. pulicaris complexes. 5. The distribution in multivariate environmental space of bluetongue virus is closer to that of the Palaearctic vectors than it is to that of C. imicola . This suggests that Palearctic vectors now play a substantial role in transmission and have facilitated the spread of bluetongue into cooler, wetter regions of Europe. 6. Synthesis and applications . The risk to Northern Europe now depends on how much of the distributions of the widespread, abundant Palearctic midge vectors (the C. obsoletus and C. pulicaris complexes) bluetongue can occupy, perhaps determined by thermal constraints on viral replication. This was highlighted by the sudden appearance in summer 2006 of bluetongue virus at latitudes of more than 50 ° North -approximately 6 ° further North than previous outbreaks in southern Europe. Future surveillance for bluetongue and for related Culicoides -borne pathogens should include studies to record and explain the distributional patterns of all potential Palearctic vector species.

SummaryRadev, V., N. Lalkovski, P. Zhelyazkov, T. Kostova, P. Sabev, N. Nedelchev & R. Vassileva, 2016. Prevalence of gastrointestinal parasites and Dirofilaria spp. in stray dogs from some regions in Bulgaria. Bulg. J. Vet. Med., 19, No 1,[57][58][59][60][61][62] During the summer seasons of two consequent years (2013)(2014), 80 faecal samples from dogs in stray shelters of two Bulgarian districts (Sofia, n=40 and Pleven, n=40) were examined for infection with gastrointestinal parasites. The flotation-centrifugation method using ZnCl 2 solution was used for parasitological examination of the samples. Thirty-three blood samples from dogs in one stray shelter (Sofia district) were tested for infection with Dirofilaria sp. by the Knott's method and the positive samples were further tested by the Combo SNAP test for Dirofilaria immitis. The obtained eggs or larvae were morphologically examined through light microscopy. The study revealed that the examined dogs from stray shelters in these districts of Bulgaria were infected with parasites belonging to eight genera -Ancylostoma, Toxocara, Toxascaris, Trichuris, Uncinaria, Dipylidium, Dirofilaria and Isospora. Among the positive dogs, Ancylostoma was the most common parasite in the Sofia district being recovered from 52.5% of the examined dogs, while Trichuris vulpis was more common in the Pleven district -20%. Dirofilaria-positive samples were 33% of all examined blood samples. Out of them, 15% were positive for infection with D. immitis and 18% -with D. repens. This study showed that the nematode infection rate in stray dogs was high and suggested the existence of a real risk for infection in humans and pets.

At the moment the most important diseases for Bulgarian pig industry are classical swine fever and Aujeszky’s disease in respect of which we are obliged to meet the require ments of the European Union (EU) as well as Porcine reproductive and respiratory syndrome and Porcine circovirus type 2, which cause big losses on pig farms. According to the experts on pig diseases we are now in the era of multifactorial diseases. The emergence of porcine reproductive and respiratory syndrome (PRRS) and porcine cyrcovirus type 2 (PCV2) in the last 15 years also lead to alteration of the pig pathology and increased the importance of multifactor diseases. Also, the diseases important for pig production in Bulgaria are the diseases: porcine parvovirus (PPV), swine influenca virus (SIV), Mycoplasma hyopneumonia (M hyo) and Actinobacillus pleuropneumoniae (APP), the infections that of ten joined with above mentioned caus ative agents.

From goat and bucks with genital disorders and abortions the attempts for isolation of caprine herpesvirus 1 (CHV 1) were carried out. For virus exaltation Dexametazone was used. For viruses isolation vaginal, nasal, rectal, preputial swabs and organ samples were used. Primary and continuous cell cultures rabbit kidney (RK), Madin Darby bovine kidney (MDBK), and embrional bovine trachea (EBTR) were used for cultivation. For determination of DNA type and lipid envelop 60 μg/ml iod desoxiuridine (JDUR) and the ether treat ment was used. Neutralization by specific hyperimmune serum obtained from Switzerland was performed. Five CHV 1 strains were isolated by cell cultures and identified as goat herpesviruses from dif ferent Bulgarian regions. After electron microscopy the viral agents with typical size and morphology for herpesviruses were established. For demonstration gC gene of CHV 1 the polymerase chain reaction (PCR) with primers designed from sequences deposited in gene bank were developed. Isolated on cell cultures herpesviruses were proved as caprine herpesvirus 1 by using applied PCR variant. The products after gC gene amplification from Bulgarian isolates were separated on the same place as the amplicons of ref er ence CHV 1 strains.