Serosurvey of arthropod-borne diseases among shelter dogs in the Cumberland Gap Region of the United States.

BACKGROUND: The Cumberland Gap Region (CGR) of the United States is a natural corridor between the southeastern, northeastern, and midwestern regions of the country. CGR has also many species of ticks and mosquitos that serve as competent vectors for important animal and human pathogens. In this study, we tested dogs from six different animal shelters in the CGR for Rocky Mountain spotted fever (RMSF), anaplasmosis, Lyme disease, canine ehrlichiosis and canine heartworm disease. RESULTS: Sera from 157 shelter dogs were tested for antibodies to RMSF agent, Rickettsia rickettsii, using an indirect immunofluorescence assay. Sixty-six dogs (42.0%) were positive for either IgM or IgG, or both IgM and IgG antibodies to R. rickettsii. Moreover, the same set of sera (n = 157) plus an and additional sera (n = 75) from resident dogs at the same shelters were tested using the SNAP 4Dx Plus. Of 232 dogs tested, two (0.9%) were positive for antibodies to Anaplasma phagocytophilum/A. platys, nine (3.9%) were positive for antibodies to Borrelia burgdorferi, 23 (9.9%) for positive for antibodies to Ehrlichia canis/E. ewingii, and 13 (5.6%) were positive for Dirofilaria immitis antigen. Co-infection with two or more etiologic agents was detected in five animals. Three dogs had antibodies to both B. burgdorferi and E. canis/E. ewingii, and two dogs were positive for D. immitis antigen and antibodies to B. burgdorferi and E. canis/E. ewingii. CONCLUSIONS: Shelter dogs in the CGR are exposed to a number of important vector-borne pathogens. Further studies are required to ascertain the roles these animals play in maintenance and transmission of these pathogens.

Mouth-clicks used by blind expert human echolocators - signal description and model based signal synthesis.

Echolocation is the ability to use sound-echoes to infer spatial information about the environment. Some blind people have developed extraordinary proficiency in echolocation using mouth-clicks. The first step of human biosonar is the transmission (mouth click) and subsequent reception of the resultant sound through the ear. Existing head-related transfer function (HRTF) data bases provide descriptions of reception of the resultant sound. For the current report, we collected a large database of click emissions with three blind people expertly trained in echolocation, which allowed us to perform unprecedented analyses. Specifically, the current report provides the first ever description of the spatial distribution (i.e. beam pattern) of human expert echolocation transmissions, as well as spectro-temporal descriptions at a level of detail not available before. Our data show that transmission levels are fairly constant within a 60° cone emanating from the mouth, but levels drop gradually at further angles, more than for speech. In terms of spectro-temporal features, our data show that emissions are consistently very brief (~3ms duration) with peak frequencies 2-4kHz, but with energy also at 10kHz. This differs from previous reports of durations 3-15ms and peak frequencies 2-8kHz, which were based on less detailed measurements. Based on our measurements we propose to model transmissions as sum of monotones modulated by a decaying exponential, with angular attenuation by a modified cardioid. We provide model parameters for each echolocator. These results are a step towards developing computational models of human biosonar. For example, in bats, spatial and spectro-temporal features of emissions have been used to derive and test model based hypotheses about behaviour. The data we present here suggest similar research opportunities within the context of human echolocation. Relatedly, the data are a basis to develop synthetic models of human echolocation that could be virtual (i.e. simulated) or real (i.e. loudspeaker, microphones), and which will help understanding the link between physical principles and human behaviour.

Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

Some blind humans have developed the remarkable ability to detect and localize objects through the auditory analysis of self-generated tongue clicks. These echolocation experts show a corresponding increase in 'visual' cortex activity when listening to echo-acoustic sounds. Echolocation in real-life settings involves multiple reflections as well as active sound production, neither of which has been systematically addressed. We developed a virtualization technique that allows participants to actively perform such biosonar tasks in virtual echo-acoustic space during magnetic resonance imaging (MRI). Tongue clicks, emitted in the MRI scanner, are picked up by a microphone, convolved in real time with the binaural impulse responses of a virtual space, and presented via headphones as virtual echoes. In this manner, we investigated the brain activity during active echo-acoustic localization tasks. Our data show that, in blind echolocation experts, activations in the calcarine cortex are dramatically enhanced when a single reflector is introduced into otherwise anechoic virtual space. A pattern-classification analysis revealed that, in the blind, calcarine cortex activation patterns could discriminate left-side from right-side reflectors. This was found in both blind experts, but the effect was significant for only one of them. In sighted controls, 'visual' cortex activations were insignificant, but activation patterns in the planum temporale were sufficient to discriminate left-side from right-side reflectors. Our data suggest that blind and echolocation-trained, sighted subjects may recruit different neural substrates for the same active-echolocation task.

Characterizing Concurrent Tobacco Product Use Among Homeless Cigarette Smokers.

INTRODUCTION: Cigarette smoking prevalence rates are high among homeless adults (>70%); however, little is known about concurrent tobacco or other nicotine product use (i.e., concurrent use [CU]) in this population. CU may impact smoking quit rates and confer greater risk of health problems within this vulnerable population. This study characterized CU in a sample of homeless smokers and compared cigarette-only smokers (C-OS) to concurrent users (CUs) on participant characteristics and factors known to be associated with smoking cessation. METHODS: Participants were 178 adult conventional cigarette smokers from a homeless shelter in Dallas, TX. Sociodemographic characteristics, number of homelessness episodes, tobacco dependence, and items characterizing use of several tobacco/nicotine products over the last 30 days including use frequency, reasons for use, and perceived health risks were described. Sociodemographic characteristics, number of homelessness episodes, tobacco dependence, stress, readiness to quit (RTQ) smoking, and number of smoking quit attempts in the last year were compared between the C-OS and CUs groups using t tests and chi-square tests. RESULTS: CU was prevalent (n = 91; 51.1%), and 49.5% of CUs reported the use of ≥2 products in addition to conventional cigarettes. Compared with C-OS, CUs were younger and had more homelessness episodes, higher expired breath carbon monoxide levels, and higher stress (ps < .05). Groups did not differ on sex, race, other dependence indicators, RTQ, or previous quit attempts. CONCLUSIONS: CU is common among homeless smokers. CUs and C-OS did not differ in their RTQ smoking, though greater stress among the CUs may represent a hurdle for cessation.

Psychophysics of human echolocation.

The skills of some blind humans orienting in their environment through the auditory analysis of reflections from self-generated sounds have received only little scientific attention to date. Here we present data from a series of formal psychophysical experiments with sighted subjects trained to evaluate features of a virtual echo-acoustic space, allowing for rigid and fine-grain control of the stimulus parameters. The data show how subjects shape both their vocalisations and auditory analysis of the echoes to serve specific echo-acoustic tasks. First, we show that humans can echo-acoustically discriminate target distances with a resolution of less than 1 m for reference distances above 3.4 m. For a reference distance of 1.7 m, corresponding to an echo delay of only 10 ms, distance JNDs were typically around 0.5 m. Second, we explore the interplay between the precedence effect and echolocation. We show that the strong perceptual asymmetry between lead and lag is weakened during echolocation. Finally, we show that through the auditory analysis of self-generated sounds, subjects discriminate room-size changes as small as 10%.In summary, the current data confirm the practical efficacy of human echolocation, and they provide a rigid psychophysical basis for addressing its neural foundations.

The flexible action system: Click-based echolocation may replace certain visual functionality for adaptive walking.

People use sensory, in particular visual, information to guide actions such as walking around obstacles, grasping or reaching. However, it is presently unclear how malleable the sensorimotor system is. The present study investigated this by measuring how click-based echolocation may be used to avoid obstacles while walking. We tested 7 blind echolocation experts, 14 sighted, and 10 blind echolocation beginners. For comparison, we also tested 10 sighted participants, who used vision. To maximize the relevance of our research for people with vision impairments, we also included a condition where the long cane was used and considered obstacles at different elevations. Motion capture and sound data were acquired simultaneously. We found that echolocation experts walked just as fast as sighted participants using vision, and faster than either sighted or blind echolocation beginners. Walking paths of echolocation experts indicated early and smooth adjustments, similar to those shown by sighted people using vision and different from later and more abrupt adjustments of beginners. Further, for all participants, the use of echolocation significantly decreased collision frequency with obstacles at head, but not ground level. Further analyses showed that participants who made clicks with higher spectral frequency content walked faster, and that for experts higher clicking rates were associated with faster walking. The results highlight that people can use novel sensory information (here, echolocation) to guide actions, demonstrating the action system's ability to adapt to changes in sensory input. They also highlight that regular use of echolocation enhances sensory-motor coordination for walking in blind people. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Leptospiral shedding and seropositivity in shelter dogs in the Cumberland Gap Region of Southeastern Appalachia.

BACKGROUND: Leptospirosis, caused by pathogenic Leptospira spp., is a zoonotic infection that affects humans, dogs and many other mammalian species. Virtually any mammalian species can act as asymptomatic reservoir, characterized by chronic renal carriage and shedding of a host-adapted leptospiral serovar. Environmental contamination by chronic shedders results in acquisition of infection by humans and susceptible animals. METHODS: In this study, we investigated if clinically normal shelter dogs and cats harbor leptospires in their kidneys by screening urine samples for the presence of leptospiral DNA by a TaqMan based-quantitative PCR (qPCR) that targets pathogen-associated lipl32 gene. To identify the infecting leptospiral species, a fragment of leptospiral rpoB gene was PCR amplified and sequenced. Additionally, we measured Leptospira-specific serum antibodies using the microscopic agglutination test (MAT), a gold standard in leptospiral serology. RESULTS: A total of 269 shelter animals (219 dogs and 50 cats) from seven shelters located in the tri-state area of western Virginia, eastern Tennessee, and southeastern Kentucky were included in this study. All cats tested negative by both qPCR and MAT. Of the 219 dogs tested in the study, 26/198 (13.1%, 95% CI: 8.4-17.8%) were positive for leptospiral DNA in urine by qPCR and 38/211 (18.0%, 95% CI: 12.8-23.2%) were seropositive by MAT. Twelve dogs were positive for both qPCR and MAT. Fourteen dogs were positive by qPCR but not by MAT. Additionally, leptospiral rpoB gene sequencing from a sub-set of qPCR-positive urine samples (n = 21) revealed L. interrogans to be the leptospiral species shed by dogs. CONCLUSIONS: These findings have significant implications regarding animal and public health in the Cumberland Gap Region and possibly outside where these animals may be adopted.

Evidence of Leptospiral Presence in the Cumberland Gap Region.

BACKGROUND: Leptospirosis is a widespread zoonotic disease that causes reproductive losses and/or hepatorenal failure in a number of animal species. Wild reservoirs of the disease, such as rodents, harbor the causative bacterium, Leptospira spp., in their kidneys and contaminate the environment by excreting infected urine. In this study, we tested small wild mammals, environmental water, and livestock in the Cumberland Gap region of southeastern Appalachia for the presence of pathogenic Leptospira or leptospiral antibodies. METHODS/RESULTS: Small wild mammals (n = 101) and environmental water samples (n = 89) were screened by a real time quantitative PCR that targets the pathogenic Leptospira-specific lipl32 gene. Kidneys from 63 small wild mammals (62.37%) and two water sources (2.25%) tested positive for leptospiral DNA. To identify the infecting leptospiral species in qPCR-positive water and kidney samples, a fragment of leptospiral rpoB gene was PCR amplified and sequenced. L. kirschneri and L. interrogans were the leptospiral species carried by small wild mammals. Furthermore, sera from livestock (n = 52; cattle and horses) were screened for leptospiral antibodies using microscopic agglutination test (MAT). Twenty sera (38.46%) from livestock had antibodies to one or more serovars of pathogenic Leptospira spp. CONCLUSIONS: In conclusion, results from our study show exposure to leptospiral infection in farm animals and the presence of this zoonotic pathogen in the environmental water and kidneys of a significant number of small wild mammals. The public health implications of these findings remain to be assessed.

Parahippocampal cortex is involved in material processing via echoes in blind echolocation experts.

Some blind humans use sound to navigate by emitting mouth-clicks and listening to the echoes that reflect from silent objects and surfaces in their surroundings. These echoes contain information about the size, shape, location, and material properties of objects. Here we present results from an fMRI experiment that investigated the neural activity underlying the processing of materials through echolocation. Three blind echolocation experts (as well as three blind and three sighted non-echolocating control participants) took part in the experiment. First, we made binaural sound recordings in the ears of each echolocator while he produced clicks in the presence of one of three different materials (fleece, synthetic foliage, or whiteboard), or while he made clicks in an empty room. During fMRI scanning these recordings were played back to participants. Remarkably, all participants were able to identify each of the three materials reliably, as well as the empty room. Furthermore, a whole brain analysis, in which we isolated the processing of just the reflected echoes, revealed a material-related increase in BOLD activation in a region of left parahippocampal cortex in the echolocating participants, but not in the blind or sighted control participants. Our results, in combination with previous findings about brain areas involved in material processing, are consistent with the idea that material processing by means of echolocation relies on a multi-modal material processing area in parahippocampal cortex.

Shape-specific activation of occipital cortex in an early blind echolocation expert.

We have previously reported that an early-blind echolocating individual (EB) showed robust occipital activation when he identified distant, silent objects based on echoes from his tongue clicks (Thaler, Arnott, & Goodale, 2011). In the present study we investigated the extent to which echolocation activation in EB's occipital cortex reflected general echolocation processing per se versus feature-specific processing. In the first experiment, echolocation audio sessions were captured with in-ear microphones in an anechoic chamber or hallway alcove as EB produced tongue clicks in front of a concave or flat object covered in aluminum foil or a cotton towel. All eight echolocation sessions (2 shapes×2 surface materials×2 environments) were then randomly presented to him during a sparse-temporal scanning fMRI session. While fMRI contrasts of chamber versus alcove-recorded echolocation stimuli underscored the importance of auditory cortex for extracting echo information, main task comparisons demonstrated a prominent role of occipital cortex in shape-specific echo processing in a manner consistent with latent, multisensory cortical specialization. Specifically, relative to surface composition judgments, shape judgments elicited greater BOLD activity in ventrolateral occipital areas and bilateral occipital pole. A second echolocation experiment involving shape judgments of objects located 20° to the left or right of straight ahead activated more rostral areas of EB's calcarine cortex relative to location judgments of those same objects and, as we previously reported, such calcarine activity was largest when the object was located in contralateral hemispace. Interestingly, other echolocating experts (i.e., a congenitally blind individual in Experiment 1, and a late blind individual in Experiment 2) did not show the same pattern of feature-specific echo-processing calcarine activity as EB, suggesting the possible significance of early visual experience and early echolocation training. Together, our findings indicate that the echolocation activation in EB's occipital cortex is feature-specific, and that these object representations appear to be organized in a topographic manner.