Natural SARS-CoV-2 Infection in Kept Ferrets, Spain.

We found severe acute respiratory syndrome coronavirus 2 RNA in 6 (8.4%) of 71 ferrets in central Spain and isolated and sequenced virus from 1 oral and 1 rectal swab specimen. Natural infection occurs in kept ferrets when virus circulation among humans is high. However, small ferret collections probably cannot maintain virus circulation.

Epidemiology of paratuberculosis in sheep and goats in southern Spain.

Paratuberculosis is a worldwide, chronic infectious disease caused by Mycobacterium avium subsp. paratuberculosis (MAP) that mainly affects ruminant species. This disease has a significant economic impact on small ruminant production due to the costs of implementing control measures and production losses. A cross-sectional study was carried out to determine the seroprevalence, spatial distribution and risk factors associated with MAP exposure in sheep and goats in Andalusia (southern Spain). Serum samples from 4134 small ruminants (2266 sheep and 1868 goats) in 153 flocks were tested by an in-house ELISA for antibodies against MAP using paratuberculosis protoplasmic antigen 3 (PPA3) as coating antigen. Antibodies against MAP were detected in 8.1% (183/2266; 95% CI: 7.0-9.2%) of sheep and 20.0% (374/1868; 95% CI: 18.2-21.8%) of goats. The true individual seroprevalence was 8.4% (95% CI: 6.9-10.1%) in sheep and 25.2% (95% CI: 22.7-27.8%) in goats. Seropositivity was detected in 66.3% (55/83; 95% CI: 56.1-76.4%) of sheep herds and 90.0% (63/70; 95% CI: 83.0-97.0%) of goat herds. Spatial analysis identified three statistically significant clusters (p < 0.05) associated with areas with higher seroprevalence of MAP. The main risk factors potentially associated with MAP exposure were: species (goat) and absence of perimeter livestock fencing. The results of this study show that MAP is widespread in small ruminant populations in southern Spain and suggest that goats may play a more important role than sheep in the transmission and maintenance of MAP. Because of animal health concerns and the economic consequences of paratuberculosis, appropriate surveillance and control programs are required to reduce the risk of MAP infections in small ruminant flocks in this country.

No effect of inoculation site and injection device on the skin test response of red deer to the intradermal injection of Mycobacterium avium-derived purified protein derivative (PPD).

Mycobacterial diseases are important health issues in farmed deer. The single intradermal tuberculin test is the standard test for tuberculosis testing in deer. We studied two factors which might influence the response of deer to skin testing: the inoculation site and the injection device. Deer included in this study were 2.5 years old farmed red deer (Cervus elaphus) hinds (n = 80). Two areas of 3 cm × 3 cm were shaved at the left side of the neck. Site A (SA) was situated about 10 cm caudal to the head, while site B (SB) was 10 cm caudal to SA. All hinds received at the same time two 0.1 ml inoculations of Mycobacterium avium derived purified protein derivative (aPPD). One inoculation was made by syringe and the other one with the needle-free syringe Dermojet. To test the inoculation site effect, half of the animals were inoculated by Dermojet in SA and by syringe in SB to compare with the inoculation in SA by syringe and Dermojet in SB in the other half. No differences were recorded for the injection device nor for the inoculation site. Ten hinds had a skinfold increase larger than 30 tenths of mm by any injection device and inoculation site. Seven (9%) and 6 (8%) hinds were classified as positive by syringe and Dermojet, and at the anterior or posterior inoculation site, respectively. The distribution of skinfold thickness increases did not differ by injection device. Our findings support the needle-free Dermojet syringe as a suitable tool for skin-testing in red deer and suggest no relevant effect of the position of the inoculation site along the neck in red deer.

Transcranial photoacoustic computed tomography based on a layered back-projection method.

A major challenge of transcranial human brain photoacoustic computed tomography (PACT) is correcting for the acoustic aberration induced by the skull. Here, we present a modified universal back-projection (UBP) method, termed layered UBP (L-UBP), that can de-aberrate the transcranial PA signals by accommodating the skull heterogeneity into conventional UBP. In L-UBP, the acoustic medium is divided into multiple layers: the acoustic coupling fluid layer between the skull and detectors, the skull layer, and the brain tissue layer, which are assigned different acoustic properties. The transmission coefficients and wave conversion are considered at the fluid-skull and skull-tissue interfaces. Simulations of transcranial PACT using L-UBP were conducted to validate the method. Ex vivo experiments with a newly developed three-dimensional PACT system with 1-MHz center frequency demonstrated that L-UBP can substantially improve the image quality compared to conventional UBP.

Simultaneous transmission and reception on all elements of an array: binary code excitation.

Pulse-echo arrays are used in radar, sonar, seismic, medical and non-destructive evaluation. There is a trend to produce arrays with an ever-increasing number of elements. This trend presents two major challenges: (i) often the size of the elements is reduced resulting in a lower signal-to-noise ratio (SNR) and (ii) the time required to record all of the signals that correspond to every transmit-receive path increases. Coded sequences with good autocorrelation properties can increase the SNR while orthogonal sets can be used to simultaneously acquire all of the signals that correspond to every transmit-receive path. However, a central problem of conventional coded sequences is that they cannot achieve good autocorrelation and orthogonality properties simultaneously due to their length being limited by the location of the closest reflectors. In this paper, a solution to this problem is presented by using coded sequences that have receive intervals. The proposed approach can be more than one order of magnitude faster than conventional methods. In addition, binary excitation and quantization can be employed, which reduces the data throughput by roughly an order of magnitude and allows for higher sampling rates. While this concept is generally applicable to any field, a 16-element system was built to experimentally demonstrate this principle for the first time using a conventional medical ultrasound probe.

Description of the first Schmallenberg disease outbreak in Spain and subsequent virus spreading in domestic ruminants.

Schmallenberg disease (SBD) is an emerging disease transmitted mainly among ruminant species by biting midges of the genus Culicoides. Since the Schmallenberg virus (SBV) was first identified in Germany in late 2011, it rapidly spread to other European countries. The aims of the present study were to describe the first SBD outbreak in Spain and to assess the spread and risk factors associated with SBV infection in domestic ruminants from nearby farms during the following year. In March 2012, one malformed stillborn lamb from a sheep farm located in Cordoba province (Southern Spain) was subjected to necropsy. Pathological compatible lesions and molecular analyses confirmed the first SBV infection in Spain. Afterwards, serum samples from 505 extensively reared domestic ruminants from 29 farms were analysed using both blocking ELISA and virus neutralization test against SBV. The overall seroprevalence was 54.4% (CI95%: 50.0-58.7). Antibodies were detected in 70.6%, 46.0% and 34.8% of cattle, sheep and goats, respectively. A generalized estimating equation model indicated that the main risk factors associated with SBV infection were: species (cattle), age (adult), and absence of animal insecticide treatment. Pathological and molecular results confirmed the presence of SBV in Spain few months after it was firstly identified in Germany. The seroprevalence detected indicates a widespread circulation of SBV in nearby domestic ruminant farms one year after this first outbreak was reported in Spain. Further studies are warranted to determine the spatio-temporal trend of SBV in domestic ruminants in this country.

Coded Excitation for Pulse-Echo Systems.

Pulse compression has been used for decades in radar, sonar, medical, and industrial ultrasound. It consists in transmitting a modulated or coded excitation, which is then cross-correlated with the received signal such that received echoes are time compressed, thereby increasing their intensity and hence the system resolution and signal-to-noise ratio (SNR). A central problem in pulse-echo systems is that while longer coded excitations yield higher SNRs, the length of the coded excitation or sequence is limited by the distance between the closest reflector and the transmitter/receiver. In this paper, a new approach to coded excitation is presented whereby receive intervals or pauses are introduced within the excitation itself; reception takes place in these intervals. As a result, the code length is no longer limited by the distance to the closest reflector and a higher SNR increase can be realized. Moreover, the excitation can be coded in such a way that continuous transmission becomes possible, which reduces the overall duration of the system response to changes in the medium. The optimal distribution of the receive intervals within the excitation is discussed, and an example of its application in industrial ultrasound is presented. The example consists of an electromagnetic-acoustic transducer driven with 4.5 V, where a clear signal can be obtained in quasi-real-time (e.g., ~9-Hz refresh rate), while commercially available systems require 1200 V for a similar performance.

The Use of Binary Quantization for the Acquisition of Low SNR Ultrasonic Signals: A Study of the Input Dynamic Range.

Low-power excitation and/or low sensitivity transducers, such as electromagnetic acoustic transducers, piezoelectric paints, air-coupled transducers, and small elements of dense arrays, may produce signals below the noise threshold at the receiver. The information from those noisy signals can be recovered after averaging or pulse compression using binary (1-b) quantization only without experiencing significant losses. Hence, no analog-to-digital converter is required, which reduces the data throughput and makes the electronics faster, more compact, and energy efficient. All these are especially attractive for applications that require arrays with many channels and high sampling rates, where the sampling rate can be as high as the system clock. In this paper, the theory of binary quantization is reviewed, mainly from previous work on wireless sensor networks, and the signal-to-noise ratio (SNR) of the input signals under which binary quantization is of practical interest for ultrasound applications is investigated. The main findings are that in most practical cases binary quantization can be used with small errors when the input SNR is on the order of 8 dB or less. Moreover, the maximum SNR after binary quantization and averaging can be estimated as 10log10N-2 dB , where N is the number of averages.