A dusty veil shading Betelgeuse during its Great Dimming.

Red supergiants are the most common final evolutionary stage of stars that have initial masses between 8 and 35 times that of the Sun1. During this stage, which lasts roughly 100,000 years1, red supergiants experience substantial mass loss. However, the mechanism for this mass loss is unknown2. Mass loss may affect the evolutionary path, collapse and future supernova light curve3 of a red supergiant, and its ultimate fate as either a neutron star or a black hole4. From November 2019 to March 2020, Betelgeuse-the second-closest red supergiant to Earth (roughly 220 parsecs, or 724 light years, away)5,6-experienced a historic dimming of its visible brightness. Usually having an apparent magnitude between 0.1 and 1.0, its visual brightness decreased to 1.614 ± 0.008 magnitudes around 7-13 February 20207-an event referred to as Betelgeuse's Great Dimming. Here we report high-angular-resolution observations showing that the southern hemisphere of Betelgeuse was ten times darker than usual in the visible spectrum during its Great Dimming. Observations and modelling support a scenario in which a dust clump formed recently in the vicinity of the star, owing to a local temperature decrease in a cool patch that appeared on the photosphere. The directly imaged brightness variations of Betelgeuse evolved on a timescale of weeks. Our findings suggest that a component of mass loss from red supergiants8 is inhomogeneous, linked to a very contrasted and rapidly changing photosphere.

Large granulation cells on the surface of the giant star π1 Gruis.

Convection plays a major part in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars, in dust clouds and on brown dwarfs. Most of our knowledge about stellar convection has come from studying the Sun: about two million convective cells with typical sizes of around 2,000 kilometres across are present on the surface of the Sun-a phenomenon known as granulation. But on the surfaces of giant and supergiant stars there should be only a few large (several tens of thousands of times larger than those on the Sun) convective cells, owing to low surface gravity. Deriving the characteristic properties of convection (such as granule size and contrast) for the most evolved giant and supergiant stars is challenging because their photospheres are obscured by dust, which partially masks the convective patterns. These properties can be inferred from geometric model fitting, but this indirect method does not provide information about the physical origin of the convective cells. Here we report interferometric images of the surface of the evolved giant star π1 Gruis, of spectral type S5,7. Our images show a nearly circular, dust-free atmosphere, which is very compact and only weakly affected by molecular opacity. We find that the stellar surface has a complex convective pattern with an average intensity contrast of 12 per cent, which increases towards shorter wavelengths. We derive a characteristic horizontal granule size of about 1.2 × 1011 metres, which corresponds to 27 per cent of the diameter of the star. Our measurements fall along the scaling relations between granule size, effective temperature and surface gravity that are predicted by simulations of stellar surface convection.

Unexpectedly large mass loss during the thermal pulse cycle of the red giant star R Sculptoris.

The asymptotic-giant-branch star R Sculptoris is surrounded by a detached shell of dust and gas. The shell originates from a thermal pulse during which the star underwent a brief period of increased mass loss. It has hitherto been impossible to constrain observationally the timescales and mass-loss properties during and after a thermal pulse--parameters that determine the lifetime of the asymptotic giant branch and the amount of elements returned by the star. Here we report observations of CO emission from the circumstellar envelope and shell around R Sculptoris with an angular resolution of 1.3″. What was previously thought to be only a thin, spherical shell with a clumpy structure is revealed to also contain a spiral structure. Spiral structures associated with circumstellar envelopes have been previously seen, leading to the conclusion that the systems must be binaries. Combining the observational data with hydrodynamic simulations, we conclude that R Sculptoris is a binary system that underwent a thermal pulse about 1,800 years ago, lasting approximately 200 years. About 3 × 10(-3) solar masses of material were ejected at a velocity of 14.3 km s(-1) and at a rate around 30 times higher than the pre-pulse mass-loss rate. This shows that about three times more mass was returned to the interstellar medium during and immediately after the pulse than previously thought.

Detection of carbapenemase- and ESBL-producing Klebsiella pneumoniae from bovine bulk milk and comparison with clinical human isolates in Italy.

Klebsiella pneumoniae is the most common Klebsiella species infecting animals and is one of the causing agents of mastitis in cows. The rise of antimicrobial resistance in K. pneumoniae, particularly in strains producing extended-spectrum ß-lactamases (ESBLs) and/or carbapenemases, is of concern worldwide. Recently (Regulation UE No 2022/1255), carbapenems and cephalosporins in combination with ß-lactamase inhibitors have been reserved only to human treatments in the European Union. The aim of this study was to investigate the role of cattle as carrier of human pathogenic carbapenem-resistant (CR) and ESBL-producing K. pneumoniae. On this purpose, a study involving 150 dairy farms in Parma province (Northern Italy) and 14 non replicate K. pneumoniae isolates from patients admitted at Parma University-Hospital was planned. Four multidrug resistant (MDR) K. pneumoniae strains were detected from 258 milk filters collected between 2019 and 2021. One carbapenemase KPC-3-positive K. pneumoniae ST307 (0.4 %; 95 % CI - 0.07 - 2.2) was detected in milk filters. The isolate also harboured OXA-9, CTX-M-15 and SHV-106 determinants, together with genes conferring resistance to aminoglycosides (aac(3')-IIa, aph (3″)-Ib, aph (6)-Id), fluoroquinolones (oqxA, oqxB, qnrB1), phosphonic acids (fosA6), sulphonamides (sul2), tetracyclines (tet(A)6) and trimethoprim (dfrA14). One KPC-3-producing K. pneumoniae ST307 was identified also among the human isolates, thus suggesting a possible circulation of pathogens out of the clinical settings. The remaining three bovine isolates were MDR ESBL-producing K. pneumoniae characterized by different genomic profiles: CTX-M-15, TEM-1B and SHV-187 genes (ST513); CTX-M-15 and SHV-145 (ST307); SHV-187 and DHA-1 (ST307). Occurrence of ESBL-producing K. pneumoniae in milk filters was 1.2 % (95 % CI 0.4-3.4). All the isolates showed resistance to aminoglycosides, 3rd-generation cephalosporins, and fluoroquinolones. Among the human isolates, two multidrug resistant ESBL-producing K. pneumoniae ST307 were found, thus confirming the circulation of this high-risk lineage between humans and cattle. Our findings suggest that food-producing animals can carry human pathogenic microorganisms harboring resistance genes against carbapenems and 3rd-generation cephalosporins, even if not treated with such antimicrobials. Moreover, on the MDR K. pneumoniae farms, the antimicrobial use was much higher than the Italian median value, thus highlighting the importance of a more prudent use of antibiotics in animal productions.

Ventral tegmental area astrocytes orchestrate avoidance and approach behavior.

The ventral tegmental area (VTA) is a heterogeneous midbrain structure, containing neurons and astrocytes, that coordinates behaviors by integrating activity from numerous afferents. Within neuron-astrocyte networks, astrocytes control signals from distinct afferents in a circuit-specific manner, but whether this capacity scales up to drive motivated behavior has been undetermined. Using genetic and optical dissection strategies we report that VTA astrocytes tune glutamatergic signaling selectively on local inhibitory neurons to drive a functional circuit for learned avoidance. In this circuit, astrocytes facilitate excitation of VTA GABA neurons to increase inhibition of dopamine neurons, eliciting real-time and learned avoidance behavior that is sufficient to impede expression of preference for reward. Loss of one glutamate transporter (GLT-1) from VTA astrocytes selectively blocks these avoidance behaviors and spares preference for reward. Thus, VTA astrocytes selectively regulate excitation of local GABA neurons to drive a distinct avoidance circuit that opposes approach behavior.

Amphetamine selectively blocks inhibitory glutamate transmission in dopamine neurons.

Amphetamine is a highly addictive psychostimulant that promotes the release of the catecholamines dopamine and norepinephrine. Amphetamine-induced release of dopamine in the midbrain inhibits the activity of dopamine neurons through activation of D2 dopamine autoreceptors. Here we show that amphetamine may also excite dopamine neurons through modulation of glutamate neurotransmission. Amphetamine potently inhibits metabotropic glutamate receptor (mGluR)-mediated IPSPs in dopamine neurons, but has no effect on ionotropic glutamate receptor-mediated EPSCs. Amphetamine desensitizes the mGluR-mediated hyperpolarization through release of dopamine, activation of postsynaptic alpha1 adrenergic receptors, and suppression of InsP3-induced calcium release from internal stores. By selectively suppressing the inhibitory component of glutamate-mediated transmission, amphetamine may promote burst firing of dopamine neurons. Through this mechanism, amphetamine may enhance phasic release of dopamine, which is important in the neural processing of reward.

Electrophysiological properties of catecholaminergic neurons in the norepinephrine-deficient mouse.

To determine how norepinephrine affects the basic physiological properties of catecholaminergic neurons, brain slices containing the substantia nigra pars compacta and locus coeruleus were studied with cell-attached and whole-cell recordings in control and dopamine beta-hydroxylase knockout (Dbh -/-) mice that lack norepinephrine. In the cell-attached configuration, the spontaneous firing rate and pattern of locus coeruleus neurons recorded from Dbh -/- mice were the same as the firing rate and pattern recorded from heterozygous littermates (Dbh +/-). During whole-cell recordings, synaptic stimulation produced an alpha-2 receptor-mediated outward current in the locus coeruleus of control mice that was absent in Dbh -/- mice. Normal alpha-2 mediated outward currents were restored in Dbh -/- slices after pre-incubation with norepinephrine. Locus coeruleus neurons also displayed similar changes in holding current in response to bath application of norepinephrine, UK 14304, and methionine-enkephalin. Dopamine neurons recorded in the substantia nigra pars compacta similarly showed no differences between slices harvested from Dbh -/- and control mice. These results indicate that endogenous norepinephrine is not necessary for the expression of catecholaminergic neuron firing properties or responses to direct agonists, but is necessary for auto-inhibition mediated by indirect alpha-2 receptor stimulation.

Noradrenergic modulation of the hyperpolarization-activated cation current (Ih) in dopamine neurons of the ventral tegmental area.

Alterations in the state of excitability of midbrain dopamine (DA) neurons from the ventral tegmental area (VTA) may underlie changes in the synaptic plasticity of the mesocorticolimbic system. Here, we investigated norepinephrine's (NE) regulation of VTA DA cell excitability by modulation of the hyperpolarization-activated cation current, Ih, with whole cell recordings in rat brain slices. Current clamp recordings show that NE (40 microM) hyperpolarizes spontaneously firing VTA DA cells (11.23+/-4 mV; n=8). In a voltage clamp, NE (40 microM) induces an outward current (100+/-24 pA; n=8) at -60 mV that reverses at about the Nernst potential for potassium (-106 mV). In addition, NE (40 microM) increases the membrane cord conductance (179+/-42%; n=10) and reduces Ih amplitude (68+/-3% of control at -120 mV; n=10). The noradrenergic alpha-1 antagonist prazosin (40 microM; n=5) or the alpha-2 antagonist yohimbine (40 microM; n=5) did not block NE effects. All NE-evoked events were blocked by the D2 antagonists sulpiride (1 microM) and eticlopride (100 nM) and no significant reduction of Ih took place in the presence of the potassium channel blocker BaCl2 (300 microM). Therefore, it is concluded that NE inhibition of Ih was due to an increase in membrane conductance by a nonspecific activation of D2 receptors that induce an outward potassium current and is not a result of a second messenger system acting on h-channels. The results also suggest that Ih channels are mainly located at dendrites of VTA DA cells and, thus, their inhibition may facilitate the transition from single-spike firing to burst firing and vice versa.

The use of a web-based interactive geographical information system for the surveillance of bluetongue in Italy.

Since 2000 Italy has experienced five epidemics of bluetongue, an arthropod-borne disease that affects primarily sheep and asymptomatically cattle, goats and wildlife ruminants. In four years the disease spread through Southern and Central Italy, involving 14 Italian regions out of 20. To control the disease, the Ministry of Health established a surveillance system that included clinical, entomological and serological surveillance elements. The National Reference Centre for Veterinary Epidemiology--Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale'--developed a Web-based National Information System (NIS) and a Geographical Information System (GIS)to collect and manage data from Veterinary Services across Italy. The system was designed to gather and spread information in order to support the management of control activities and to provide an early warning system. Surveillance data are displayed to the user in different ways: reports, tables and interactive maps.

Antipanic effect of fluoxetine measured by CO2 challenge test.

BACKGROUND: Respiratory symptoms are important in panic disorder for frequency and intensity. Patients with this disorder are often chronic hyperventilators, and inhalation of carbon dioxide is a strong panicogenic stimulus. We tested the hypothesis of whether respiratory parameters may be used as indicators of the course of panic disorder during its treatment with fluoxetine. METHODS: Nine patients with panic disorders, previously shown to panic in response to intravenously administered lactate, and 10 control subjects underwent the Read rebreathing test by a 5-min inhalation of a 7% CO2/93% O2 mixture before and after 1 month of fluoxetine treatment. RESULTS: At baseline, patients differed from controls for higher percent value of expiratory reserve volume/vital capacity ratio and ventilatory response. Eight of the 9 patients had panic in response to the CO2 challenge. After fluoxetine, respiratory parameters decreased significatively, and only 3 patients remained hypercarbic challenge responders. CONCLUSIONS: The carbon dioxide challenge may represent a useful tool to evaluate the individual respiratory set, which may be a marker of the vulnerability to panic attack. Assessment of respiratory parameters may represent a biological marker to measure the efficacy of antipanic treatment.

Striatal, pallidal, and pars reticulata evoked inhibition of nigrostriatal dopaminergic neurons is mediated by GABA(A) receptors in vivo.

Dopaminergic neurons express both GABA(A) and GABA(B) receptors and GABAergic inputs play a significant role in the afferent modulation of these neurons. Electrical stimulation of GABAergic pathways originating in neostriatum, globus pallidus or substantia nigra pars reticulata produces inhibition of dopaminergic neurons in vivo. Despite a number of prior studies, the identity of the GABAergic receptor subtype(s) mediating the inhibition evoked by electrical stimulation of neostriatum, globus pallidus, or the axon collaterals of the projection neurons from substantia nigra pars reticulata in vivo remain uncertain. Single-unit extracellular recordings were obtained from substantia nigra dopaminergic neurons in urethane anesthetized rats. The effects of local pressure application of the selective GABA(A) antagonists, bicuculline and picrotoxin, and the GABA(B) antagonists, saclofen and CGP-55845A, on the inhibition of dopaminergic neurons elicited by single-pulse electrical stimulation of striatum, globus pallidus, and the thalamic axon terminals of the substantia nigra pars reticulata projection neurons were recorded in vivo. Striatal, pallidal, and thalamic induced inhibition of dopaminergic neurons was always attenuated or completely abolished by local application of the GABA(A) antagonists. In contrast, the GABA(B) antagonists, saclofen or CGP-55845A, did not block or attenuate the stimulus-induced inhibition and at times even increased the magnitude and/or duration of the evoked inhibition. Train stimulation of globus pallidus and striatum also produced an inhibition of firing in dopaminergic neurons of longer duration. However this inhibition was largely insensitive to either GABA(A) or GABA(B) antagonists although the GABA(A) antagonists consistently blocked the early portion of the inhibitory period indicating the presence of a GABA(A) component. These data demonstrate that dopaminergic neurons of the substantia nigra pars compacta are inhibited by electrical stimulation of striatum, globus pallidus, and the projection neurons of substantia nigra pars reticulata in vivo. This inhibition appears to be mediated via the GABA(A) receptor subtype, and all three GABAergic afferents studied appear to possess inhibitory presynaptic GABA(B) autoreceptors that are active under physiological conditions in vivo.

GABAergic control of rat substantia nigra dopaminergic neurons: role of globus pallidus and substantia nigra pars reticulata.

Dopaminergic neurons in vivo fire spontaneously in three distinct patterns or modes. It has previously been shown that the firing pattern of substantia nigra dopaminergic neurons can be differentially modulated by local application of GABA(A) and GABA(B) receptor antagonists. The GABA(A) antagonists, bicuculline or picrotoxin, greatly increase burst firing in dopaminergic neurons whereas GABA(B) antagonists cause a modest shift away from burst firing towards pacemaker-like firing. The three principal GABAergic inputs to nigral dopaminergic neurons arise from striatum, globus pallidus and from the axon collaterals of nigral pars reticulata projection neurons, each of which appear to act in vivo primarily on GABA(A) receptors (see preceding paper). In this study we attempted to determine on which afferent pathway(s) GABA(A) antagonists were acting to cause burst firing. Substantia nigra dopaminergic neurons were studied by single unit extracellular recordings in urethane anesthetized rats during pharmacologically induced inhibition and excitation of globus pallidus. Muscimol-induced inhibition of pallidal neurons produced an increase in the regularity of firing of nigral dopaminergic neurons together with a slight decrease in firing rate. Bicuculline-induced excitation of globus pallidus neurons produced a marked increase in burst firing together with a modest increase in firing rate. These changes in firing rate were in the opposite direction to what would be expected for a monosynaptic GABAergic pallidonigral input. Examination of the response of pars reticulata GABAergic neurons to similar manipulations of globus pallidus revealed that the firing rates of these neurons were much more sensitive to changes in globus pallidus neuron firing rate than dopaminergic neurons and that they responded in the opposite direction. Pallidal inhibition produced a dramatic increase in the firing rate of pars reticulata GABAergic neurons while pallidal excitation suppressed the spontaneous activity of pars reticulata GABAergic neurons. These data suggest that globus pallidus exerts significant control over the firing rate and pattern of substantia nigra dopaminergic neurons through a disynaptic pathway involving nigral pars reticulata GABAergic neurons and that at least one important way in which local application of bicuculline induces burst firing of dopaminergic neurons is by disinhibition of this tonic inhibitory input.

GABAA receptor stimulation blocks NMDA-induced bursting of dopaminergic neurons in vitro by decreasing input resistance.

The effects of the GABAA agonist, isoguvacine, on NMDA-induced burst firing of substantia nigra dopaminergic neurons were studied with intracellular and whole cell recordings in vitro. NMDA application caused the neurons to fire in rhythmic bursts. Although the NMDA-induced bursty firing pattern was insensitive to hyperpolarization by current injection, it was reversibly abolished by the selective GABAA agonist, isoguvacine. The block of the rhythmic burst pattern by isoguvacine application occurred regardless of whether the chloride reversal potential was hyperpolarizing (ECl-=-70 mV) or depolarizing (ECl-=-40 mV). In either case, the input resistance of the dopaminergic neurons was dramatically decreased by application of isoguvacine. It is concluded that GABAA receptor activation by isoguvacine disrupts NMDA receptor-mediated burst firing by increasing the input conductance and thereby shunting the effects of NMDA acting at a distally located generator of rhythmic burst firing.

Ultrasound aspects of fetal and extrafetal structures in pregnant cats.

Prenatal feline fetal growth and utero-placental development were ultrasonographically evaluated using an ultrasound scanner with a 10 MHz sector probe. Uterus, placenta, embryo, fetus and fetal membranes in 16 pregnant cats were monitored during the course of pregnancy; 13 subjects underwent an ovariectomy on specific days while three subjects went to term. Various anatomic structures, fixed in Carson-buffered formalin, were sectioned and then compared to ultrasound images. By ultrasound examination it is possible to evaluate every stage of the fetal development; the gestational chamber can be seen on the 10th and the embryo inside the chamber on the 14th day. By the 20th day it is possible to evaluate all the fetal membranes, and later it is possible to appreciate organs and structures such as the stomach, intestine, eyes (crystalline lens), kidneys and the cerebral choroid plexi, on the 30th, 40th, 50th, 39th and 40th day respectively. Based on our observations, it will be simpler to locate anomalies of development or pathologies during ultrasound examination of pregnant queens.

Generating bursts (and pauses) in the dopamine midbrain neurons.

Dopamine (DA) midbrain neurons project to several striatal and cortical target areas and are essentially involved in a puzzling variety of important brain functions such as action selection and motor performance, motivation and reward-based learning, but also working memory and cognition. These neurons act via the release of their (main) neurotransmitter, dopamine, which binds to metabotropic dopamine receptors of the D1 or D2 type on target neurons. Axonal but also dendritic dopamine release is essentially controlled by calcium-triggered exocytosis of dopamine-filled synaptic vesicles primarily driven by electrical activity of the dopamine neuron, which generates patterns of actions potentials in the somato-dendritic domain and distributes them along its axonal tree. Thus, recording the behaviorally relevant pattern of electrical activity in DA neurons and identifying the underlying biophysical mechanisms that integrate afferent synaptic inputs and intrinsic excitability constitute a crucial element for defining the physiological roles of the midbrain DA system. Electrical activity of midbrain DA neurons in vivo is characterized by tonic background activity in a narrow frequency range (ca. 1-8Hz) interrupted by either transient (i.e. phasic, <500ms) sequences of high-frequency firing (>15Hz), so called "bursts", or transient pauses of electrical activity, where DA neurons generate no action potentials. This review focuses on the properties of these phasic activity changes in midbrain DA neurons. It updates recent progress on the expanding behavioral contexts, associated with phasic electrical activity in DA neurons beyond the classical (canonical) reward prediction error model. The review also highlights recently defined contributions of synaptic inputs for burst and pause generation and the roles of distinct postsynaptic ion channels in midbrain DA neurons.

Bluetongue serotype 2 and 9 modified live vaccine viruses as causative agents of abortion in livestock: a retrospective analysis in Italy.

The recent outbreak caused by Schmallenberg virus, which affected sheep, goats and cattle in Europe, highlighted the importance of having a robust surveillance plan capable of monitoring abortions and malformations in the livestock offspring. In this context, bluetongue viruses (BTVs) represented and represent one of the major threats to the European livestock industry. Aiming to improve the understanding on BTV cross placental transmission and serotype involvement, in this retrospective study foetal spleens and/or brains of 663 ovines, 429 bovines, 155 goats and 17 buffaloes were tested for the presence of BTV by virus isolation. BTV vaccine strains were isolated from 31 foetuses (2.4%; 95% CI: 1.7-3.4%): 24 (3.6%; 95% CI: 2.4-5.3%) from ovine foetal tissues; 6 (1.4%; 95% CI: 0.6-3.0%) from bovine foetal tissues and 1 (0.6%; 95% CI: 0.2-3.5%) from the spleen of a caprine foetus. All foetuses were from animals vaccinated with either BTV-2 or BTV-2, and BTV-9 modified live vaccines (MLVs) produced by Onderstepoort Biological Products (OBP), South Africa. Among the 31 isolated vaccine strains, serotype 9 (n = 28) was more frequently isolated (P < 0.05) than serotype 2 (n = 3). In two cases infectious vaccine strains were found in the foetal tissues 2 months after the vaccine administration. Other pathogens known to be causative agents of abortion in ruminants were not detected nor isolated. This study demonstrates, for the first time, that BTV-2 and BTV-9 vaccine strains are able to cross the placental barrier of sheep, cattle and goats. BTV-2 and BTV-9 vaccine strains are able to infect foetuses and cause abortions or malformations depending on the period of pregnancy at the time of vaccination.

Detection of bursts and pauses in spike trains.

Midbrain dopaminergic neurons in vivo exhibit a wide range of firing patterns. They normally fire constantly at a low rate, and speed up, firing a phasic burst when reward exceeds prediction, or pause when an expected reward does not occur. Therefore, the detection of bursts and pauses from spike train data is a critical problem when studying the role of phasic dopamine (DA) in reward related learning, and other DA dependent behaviors. However, few statistical methods have been developed that can identify bursts and pauses simultaneously. We propose a new statistical method, the Robust Gaussian Surprise (RGS) method, which performs an exhaustive search of bursts and pauses in spike trains simultaneously. We found that the RGS method is adaptable to various patterns of spike trains recorded in vivo, and is not influenced by baseline firing rate, making it applicable to all in vivo spike trains where baseline firing rates vary over time. We compare the performance of the RGS method to other methods of detecting bursts, such as the Poisson Surprise (PS), Rank Surprise (RS), and Template methods. Analysis of data using the RGS method reveals potential mechanisms underlying how bursts and pauses are controlled in DA neurons.

Dynamic regulation of midbrain dopamine neuron activity: intrinsic, synaptic, and plasticity mechanisms.

Although the roles of dopaminergic signaling in learning and behavior are well established, it is not fully understood how the activity of dopaminergic neurons is dynamically regulated under different conditions in a constantly changing environment. Dopamine neurons must integrate sensory, motor, and cognitive information online to inform the organism to pursue outcomes with the highest reward probability. In this article, we provide an overview of recent advances on the intrinsic, extrinsic (i.e., synaptic), and plasticity mechanisms controlling dopamine neuron activity, mostly focusing on mechanistic studies conducted using ex vivo brain slice preparations. We also hope to highlight some unresolved questions regarding information processing that takes place at dopamine neurons, thereby stimulating further investigations at different levels of analysis.

First evidence of bluetongue virus serotype 16 in Croatia.

This study described the first report of BTV-16 in Croatia. Serological evidence occurred in cattle at the end of September and continued during October and November 2004. All positive animals were in the Dubrovnik-Neretva County, a region located in the southernmost part of Croatia. BTV-16 infection was also detected in goats and sheep. Apart from few cases reported in Greece between 1999 and 2000, BTV-16 has never been reported in the Balkanic peninsula before. The BTV strain was isolated from cattle blood samples and typed as BTV-16. When the S5 was sequenced, it showed 100% homology with the BTV-16 vaccine isolate produced by Ondersterpoort Biological Product (SA) and used in Italy during the 2004 BT vaccination campaign. On the other hand no complete homology was found when the same RNA segment sequence was compared with that of the homologous Italian field isolate. As no evidence of livestock movements from Italy was demonstrated, an eolic transmission of the infection through infected Culicoides was hypothesised. According to the local meteostations, in several occasions, during the 2004 summer months, the west-east breeze blew with a speed above 50 km/h from Italy towards the Dubrovnik County. It is concluded that the BTV-16 which infected Croatian livestock was similar to the homologous OBP vaccine isolate and it is likely that it was introduced from Italy into the Southern regions of Croatia through infected Culicoides carried by the wind.