Coxiella burnetii in Humans and Ticks in Rural Senegal

Q fever is a zoonotic disease known since 1937. The disease may be severe, causing pneumonia, hepatitis and endocarditis. Q fever agent has been described as a possible biological weapon. Animals—especially domestic cows, goats and sheep—are considered reservoirs for this infection. They are capable of sustaining the infection for long periods and excreting viable bacteria, infecting other animals and, occasionally, humans. Here we studied the distribution of Q fever in a poorly studied region, Senegal. We studied the agent of Q fever both in ticks parasitizing domestic animals and in humans (antibodies in serum, bacteria in feces, saliva and milk). We found from the studied regions the bacterium is highly prevalent in rural Senegal. Up to 37.6% of five different and most prevalent tick species may carry the bacterium. Humans living in such areas, as other mammals, may occasionally excrete Q fever agent through feces and milk

Prevalence of Coxiella burnetii in clinically healthy German sheep flocks

<p>Abstract</p> <p>Background</p> <p>Current epidemiological data on the situation of <it>Coxiella (C.) burnetii </it>infections in sheep are missing, making risk assessment and the implementation of counteractive measures difficult. Using the German state of Thuringia as a model example, the estimated sero-, and antigen prevalence of <it>C. burnetii </it>(10% and 25%, respectively) was assessed at flock level in 39/252 randomly selected clinically healthy sheep flocks with more than 100 ewes and unknown abortion rate.</p> <p>Results</p> <p>The CHECKIT™ Q-fever Test Kit identified 11 (28%) antibody positive herds, whereas real-time PCR revealed the presence of <it>C. burnetii </it>DNA in 2 (5%) of the flocks. Multiple-locus variable number of tandem repeats analysis of 9 isolates obtained from one flock revealed identical profiles. All isolates contained the plasmid QpH1.</p> <p>Conclusions</p> <p>The results demonstrate that <it>C. burnetii </it>is present in clinically inconspicuous sheep flocks and sporadic flare-ups do occur as the notifications to the German animal disease reporting system show. Although <it>C. burnetii </it>infections are not a primary veterinary concern due to the lack of significant clinical impact on animal health (with the exception of goats), the eminent zoonotic risk for humans should not be underestimated. Therefore, strategies combining the interests of public and veterinary public health should include monitoring of flocks, the identification and culling of shedders as well as the administration of protective vaccines.</p

Management of a caseous lymphadenitis outbreak in a new Iberian ibex (Capra pyrenaica) stock reservoir

Background: In 2010, an Iberian ibex (Capra pyrenaica hispanica) stock reservoir was established for conservation purposes in north-eastern Spain. Eighteen ibexes were captured in the wild and housed in a 17 hectare enclosure. Once in captivity, a caseous lymphadenitis (CLA) outbreak occurred and ibex handlings were carried out at six-month intervals between 2010 and 2013 to perform health examinations and sampling. Treatment with a bacterin-based autovaccine and penicillin G benzatine was added during the third and subsequent handlings, when infection by Corynebacterium pseudotuberculosis was confirmed. Changes in lesion score, serum anti-C. pseudotuberculosis antibodies and haematological parameters were analyzed to assess captivity effects, disease emergence and treatment efficacy. Serum acute phase proteins (APP) Haptoglobin (Hp), Amyloid A (SAA) and Acid Soluble Glycoprotein (ASG) concentrations were also determined to evaluate their usefulness as indicators of clinical status.Once in captivity, 12 out of 14 ibexes (85.7%) seroconverted, preceding the emergence of clinical signs; moreover, TP, WBC, eosinophil and platelet cell counts increased while monocyte and basophil cell counts decreased. After treatment, casualties and fistulas disappeared and both packed cell volume (PCV) and haemoglobin concentration significantly increased. Hp, SAA and ASG values were under the limit of detection or showed no significant differences. Conclusions: A role for captivity in contagion rate is suggested by the increase in antibody levels against C. pseudotuberculosis and the emergence of clinical signs. Although boosted by captivity, this is the first report of an outbreak of caseous lymphadenitis displaying high morbidity and mortality in wild ungulates. Treatment consisting of both vaccination and antibiotic therapy seemed to prevent mortality and alleviate disease severity, but was not reflected in the humoural response. Haematology and APP were not useful indicators in our study, perhaps due to the sampling frequency. Presumably endemic and irrelevant in the wild, this common disease of domestic small ruminants is complicating conservation efforts for the Iberian ibex in north-eastern Spain

Dermacentor reticulatus: a vector on the rise

Dermacentor reticulatus is a hard tick species with extraordinary biological features. It has a high reproduction rate, a rapid developmental cycle, and is also able to overcome years of unfavourable conditions. Dermacentor reticulatus can survive under water for several months and is cold-hardy even compared to other tick species. It has a wide host range: over 60 different wild and domesticated hosts are known for the three active developmental stages. Its high adaptiveness gives an edge to this tick species as shown by new data on the emergence and establishment of D. reticulatus populations throughout Europe. The tick has been the research focus of a growing number of scientists, physicians and veterinarians. Within the Web of Science database, more than a fifth of the over 700 items published on this species between 1897 and 2015 appeared in the last three years (2013–2015). Here we attempt to synthesize current knowledge on the systematics, ecology, geographical distribution and recent spread of the species and to highlight the great spectrum of possible veterinary and public health threats it poses. Canine babesiosis caused by Babesia canis is a severe leading canine vector-borne disease in many endemic areas. Although less frequently than Ixodes ricinus, D. reticulatus adults bite humans and transmit several Rickettsia spp., Omsk haemorrhagic fever virus or Tick-borne encephalitis virus. We have not solely collected and reviewed the latest and fundamental scientific papers available in primary databases but also widened our scope to books, theses, conference papers and specialists colleagues’ experience where needed. Besides the dominant literature available in English, we also tried to access scientific literature in German, Russian and eastern European languages as well. We hope to inspire future research projects that are necessary to understand the basic life-cycle and ecology of this vector in order to understand and prevent disease threats. We conclude that although great strides have been made in our knowledge of the eco-epidemiology of this species, several gaps still need to be filled with basic research, targeting possible reservoir and vector roles and the key factors resulting in the observed geographical spread of D. reticulatus. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1599-x) contains supplementary material, which is available to authorized users

Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

Neural model of the multi-stable dynamics of the perception of body motion

Multi-stable perception refers to the association of the same visual stimulus with multiple alternative percepts. So far multi-stability has been studied primarily in the context of low-level vision and shape recognition. Multi-stability has also been observed during the perception of body motion, especially if the associated depth information is ambiguous [1]. In this case the same action stimulus is associated, for example, with multiple alternative walking directions. In psychophysical experiments it has been demonstrated that body motion perception can show spontaneous perceptual switching between different interpretations and hysteresis, if a stimulus parameter is gradually varied that introduces a bias for one of the two perceptual interpretations. We present a physiologically-inspired neural model that provides a unifying account for this perceptual multi-stability and multiple psychophysical experiments that characterize the underlying perceptual dynamics. Our model includes the following parts: (1) a deep neural hierarchy that recognizes body shapes from silhouette features and shading gradients of the moving figure; (2) a fast dynamic neural layer that can be interpreted as 2D neural field whose dimensions encode the stimulus view and the temporal order of the body shapes within action sequences; (3) a slower bistable read-out network that pools neural responses over the body shapes belonging to the same action and view over time-points. Our model provides a unifying account for a number psychophysical results from the literature, and from our own experiments: (a) dependence of percept probabilities on shading cues, (b) illusory misperception of walking direction for body stimuli that are illuminated from below [2]; (c) perceptual hysteresis for the gradual variation of disambiguating shading cues of body motion stimuli [3]. Our results show that the multi-stability of body motion perception can be accounted for in a simple way by the interaction between deep example-based neural networks for the recognition of body shapes and an elementary physiologically plausible cortical activation dynamics (Fig. 1)

Modeling of the perceptual dynamics of the perception of body motion

Dynamic phenomena of perceptual organization and multi-stable perception have been studied extensively since the time of Gestalt psychology, typically with low-level vision. Recent work demonstrates multi-stability and adaptation for high-level body motion perception. We have developed a neurodynamical model that reproduces multi-stability and adaptation in body motion perception. Our model consists of hierarchies of neural detectors that analyze the silhouette and the shading features of body motion stimuli, which are encoded as temporal sequences of patterns by a dynamic neural field (Fig 1A). Its multi-stable dynamics accounts for spontaneous perceptual switching. In addition, its neurons are adaptive, accounting for high-level after-effects. Further details of the implementation are discussed in [2].We showed elsewhere that the model reproduces the perceptual multi-stability of body motion perception and its dependence on shading cues [2]. Here we show additional simulations reproducing the following experimental results: (i) High-level after-effects and the time course of adaptation (Figure 1B). For a bistable stimulus the probability of seeing the percept shown during adaptation decays with the duration of the adaptor, with a time constant that is similar to the one found in experiments [1]. (ii) Exploiting a novel stimulus (inset Figure 1A) that for which perception can be biased towards one of the two perceptual alternatives, we find the time for the first perceptual switch in the region where both percepts are equally stable. By adjusting 2 parameters, we could match the observed behavior to the psychophysically measured switching times (Figure 1C). A physiologically-inspired hierarchical (‘deep’) neural model for body motion perception reproduces a multitude of effects that characterize the dynamics of body motion perception. The model makes concrete predictions about the behavior of single cells in body motion-sensitive areas

Dynamics of multistable biological motion perception

The dynamic stability of percepts has been extensively studied in low-level motion (Hock et al. 2003, 1996). A manifestation of dynamic stability is the perceptual hysteresis shown for a pair of mutually exclusive motion stimuli. So far hysteresis effects have not been investigated in biological motion perception. Its measurement requires a parameter that controls the relative bias of perception for the two alternatives. We developed such a stimulus for biological motion perception and investigated dynamic stability. METHODS: Our stimulus is based on the fact that body motion perception from two-dimensional movies can be bistable (Vanrie et al. 2004), alternating between two different percepts. We developed a new stimulus by random sampling two shaded volumetric walkers covered with 1050 circular discs. The fraction of discs drawn from either walker is a hysteresis parameter that allows to vary gradually the preference for two perceived walking directions. We realized two experiments: I. Measurement of the times before the first perceptual switch as function of the hysteresis parameter. II. Measurement of a hysteresis loop, varying the hysteresis parameter gradually up and down. This experiment adapted the Modified Method of Limits by (Hock et al. 1993). RESULTS: Experiment I shows that, dependent on the hysteresis parameter, the new stimulus can induce both an unambiguous perception of walking direction and perceptual bistability. The average switching time is smallest if both percepts are equally likely and it depends systematically on the hysteresis parameter (p < 10-15). Experiment II measured the percept probabilities as function of the hysteresis parameter. These probabilities are significantly dependent on previous values of the parameter (i.e. whether it was increasing or decreasing), implying perceptual hysteresis (p < 0.01). CONCLUSION: We demonstrated that body motion perception, like low-level motion perception, shows indicators of dynamic multi-stability