VTechWorks Repository :: Browsing by Author "Alexander, Kathleen A."

Browsing by Author "Alexander, Kathleen A."

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Anthropogenic landscapes increase Campylobacter jejuni infections in urbanizing banded mongoose (Mungos mungo): A one health approach
Medley, Sarah; Ponder, Monica A.; Alexander, Kathleen A. (PLOS, 2020-03-17)
Background: Campylobacter is a common, but neglected foodborne-zoonotic pathogen, identified as a growing cause of foodborne disease worldwide. Wildlife and domestic animals are considered important reservoirs, but little is known about pathogen infection dynamics in free-ranging mammalian wildlife particularly in sub-Saharan Africa. In countries like Botswana, there is significant overlap between humans and wildlife, with the human population having one of the highest HIV infection rates in the world, increasing vulnerability to infection. Methodology/Principal findings: We investigated Campylobacter occurrence in archived human fecal samples (children and adults, n = 122, 2011), feces from free-ranging banded mongooses (Mungos mungo, n = 201), surface water (n = 70), and river sediment samples (n = 81) collected in 2017 from the Chobe District, northern Botswana. Campylobacter spp. was widespread in humans (23.0%, 95% CI 13.9–35.4%), with infections dominantly associated with C. jejuni (82.1%, n = 28, 95% CI 55.1–94.5%). A small number of patients presented with asymptomatic infections (n = 6). While Campylobacter spp. was rare or absent in environmental samples, over half of sampled mongooses tested positive (56%, 95% CI 45.6–65.4%). Across the urbanwilderness continuum, we found significant differences in Campylobacter spp. detection associated with the type of den used by study mongooses. Mongooses utilizing man-made structures as den sites had significantly higher levels of C. jejuni infection (p = 0.019) than mongooses using natural dens. Conversely, mongooses using natural dens had overall higher levels of detection of Campylobacter at the genus level (p = 0.001). Conclusions: These results suggest that landscape features may have important influences on Campylobacter species exposure and transmission dynamics in wildlife. In particular, data suggest that human-modified landscapes may increase C. jejuni infection, a primarily human pathogen, in banded mongooses. Pathogen circulation and transmission in urbanizing wildlife reservoirs may increase human vulnerability to infection, findings that may have critical implications for both public and animal health in regions where people live in close proximity to wildlife.
Antibiotic Susceptibility of non-pathogenic Escherichia coli from meat and produce available in the Chobe region of Botswana
Saunders, Rachel; Bywater, Auja L.; Fleming, Madison; Kelly, Christine; Nuckolls, Evan; Alexander, Kathleen A.; Ponder, Monica A. (2023-04-21)
Antimicrobial Resistance Mitigation [ARM] Concept Paper
Vikesland, Peter J.; Alexander, Kathleen A.; Badgley, Brian D.; Krometis, Leigh-Anne H.; Knowlton, Katharine F.; Gohlke, Julia M.; Hall, Ralph P.; Hawley, Dana M.; Heath, Lenwood S.; Hession, W. Cully; Hull, Robert Bruce IV; Moeltner, Klaus; Ponder, Monica A.; Pruden, Amy; Schoenholtz, Stephen H.; Wu, Xiaowei; Xia, Kang; Zhang, Liqing (Virginia Tech, 2017-05-15)
The development of viable solutions to the global threat of antimicrobial resistance requires a transdisciplinary approach that simultaneously considers the clinical, biological, social, economic, and environmental drivers responsible for this emerging threat. The vision of the Antimicrobial Resistance Mitigation (ARM) group is to build upon and leverage the present strengths of Virginia Tech in ARM research and education using a multifaceted systems approach. Such a framework will empower our group to recognize the interconnectedness and interdependent nature of this threat and enable the delineation, development, and testing of resilient approaches for its mitigation. We seek to develop innovative and sustainable approaches that radically advance detection, characterization, and prevention of antimicrobial resistance emergence and dissemination in human-dominated and natural settings...
Association with humans and seasonality interact to reverse predictions for animal space use
Laver, Pete N.; Alexander, Kathleen A. (2018-04-16)
Background Variation in animal space use reflects fitness trade-offs associated with ecological constraints. Associated theories such as the metabolic theory of ecology and the resource dispersion hypothesis generate predictions about what drives variation in animal space use. But, metabolic theory is usually tested in macro-ecological studies and is seldom invoked explicitly in within-species studies. Full evaluation of the resource dispersion hypothesis requires testing in more species. Neither have been evaluated in the context of anthropogenic landscape change. Methods In this study, we used data for banded mongooses (Mungos mungo) in northeastern Botswana, along a gradient of association with humans, to test for effects of space use drivers predicted by these theories. We used Bayesian parameter estimation and inference from linear models to test for seasonal differences in space use metrics and to model seasonal effects of space use drivers. Results Results suggest that space use is strongly associated with variation in the level of overlap that mongoose groups have with humans. Seasonality influences this association, reversing seasonal space use predictions historically-accepted by ecologists. We found support for predictions of the metabolic theory when moderated by seasonality, by association with humans and by their interaction. Space use of mongooses living in association with humans was more concentrated in the dry season than the wet season, when historically-accepted ecological theory predicted more dispersed space use. Resource richness factors such as building density were associated with space use only during the dry season. We found negligible support for predictions of the resource dispersion hypothesis in general or for metabolic theory where seasonality and association with humans were not included. For mongooses living in association with humans, space use was not associated with patch dispersion or group size over both seasons. Conclusions In our study, living in association with humans influenced space use patterns that diverged from historically-accepted predictions. There is growing need to explicitly incorporate human–animal interactions into ecological theory and research. Our results and methodology may contribute to understanding effects of anthropogenic landscape change on wildlife populations.
Behavior - Landscape Interactions May Create Super-Spreader Environments: Vigilance-Olfactory Interactions Across Land Type and Disease Transmission Potential in the Banded Mongoose
Alexander, Kathleen A.; Nichols, Carol Anne (Frontiers, 2020-03-12)
A complex suite of drivers can influence infectious disease transmission with behavior and landscape spatial dynamics contributing importantly to epidemic patterns across host–pathogen-environmental systems. However, our understanding of the interaction between landscape and host behavior and its influence on spatial variability in pathogen transmission is limited. In the banded mongoose (Mungos mungo), a novel tuberculosis pathogen, Mycobacterium mungi, has emerged in Northern Botswana, which is transmitted through olfactory communication behaviors. We evaluated how associations between landscape type and mongoose behaviors affect the frequency of olfactory communication behaviors and pathogen transmission potential. We used remote sensing camera traps at den sites to eliminate observer influence across human-modified and natural landscapes (n = 18 troops, 18,229 detections of banded mongooses from 7,497 photographs). Using generalized linear mixed models, we identified a significant effect of vigilance and the interactions between vigilance and landscape, and vigilance and troop count on the frequency of olfactory behaviors. Troop count-vigilance interactions had a negative influence on olfactory communication. Vigilance, however, appeared to have a bidirectional association with olfactory communication depending on land type. In lodge areas, vigilance was associated with increased olfactory behaviors, but in landscapes with expected increases in predation risk (i.e., national park and urban land-use areas), vigilance had a negative association with olfactory behaviors. The interaction between behavior and landscape type may have the potential to create “super-spreading” environments, or transmission hotspots, where behavior-landscape interactions increase pathogen shedding and transmission potential.
Bidirectional interactions between behavior and disease in banded mongooses (Mungos mungo) infected with Mycobacterium mungi
Fairbanks, Bonnie Marie (Virginia Tech, 2013-09-04)
Behavior and disease interact bidirectionally and on multiple levels of host organization, and these interactions can have important consequences for population-level disease dynamics. I explored how behavior can both influence and respond to infectious disease in a banded mongoose population experiencing epidemics of tuberculosis (TB) caused by the bacterial pathogen Mycobacterium mungi in the M. tuberculosis complex (Alexander et al. 2010). Banded mongooses are highly social carnivores that live in troops of 5 to 65 individuals. Mycobacterium mungi appears to be primarily environmentally transmitted, but direct horizontal transmission cannot be ruled out. Approximately 10-20% of mongooses become diseased with TB each year in the study population in and around Chobe National Park, Botswana, and all mongooses with clinical signs of TB die within months. Characteristics of both banded mongooses and clinical TB provided a productive study system for exploring interactions between behavior and disease: first, free-living mongooses can be habituated and directly observed; second, the clinical signs of TB can be visually assessed non-invasively; and third, the mongooses' high sociality and egalitarianism provide a unique and ecologically relevant host social system for examining bidirectional interactions between behavior and infectious disease. I found that banded mongooses influenced and responded to disease through their behavior at both the individual and troop level, with possible implications for banded mongoose population and disease dynamics. Due to the environmental transmission of M. mungi, which appears to invade mongooses through breaks in the skin and nasal planum (Alexander et al. 2010), I focused on aggressive interactions as a potential risk factor for acquiring TB in this system. Troops with higher levels of aggression had more injuries, and at the individual level, injuries were a strong predictor of TB, suggesting that aggression may increase risk of disease by creating potential invasion sites for the pathogen. Troops were more aggressive when they foraged in garbage than when they foraged in other habitats, presumably due to the concentration of resources at this highly modified habitat. Overall, my results on how behavior can influence disease in this system suggest that anthropogenic supplementation of food, albeit inadvertent in this system, augments aggression levels in banded mongooses and may in turn lead to a higher incidence of TB. Second, I examined how behavior responds to disease in banded mongooses. Diseased individuals showed significantly lower activity and alertness, but intriguingly, did not show a reduction in overall social behaviors. Diseased individuals were less likely to disperse than healthy individuals, and healthy individuals with diseased troopmates may have been more likely to disperse than individuals without diseased troopmates. Despite this latter possible increase in dispersal in the presence of diseased conspecifics, diseased individuals were not avoided by their troopmates in daily social interactions. For example, diseased individuals were allogroomed at a higher than expected rate even though their reciprocation during allogrooming was approximately half that of healthy individuals. These interactions between behavior and disease have implications for banded mongoose troop and population dynamics, via changes in dispersal behavior and mortality, and can also affect disease dynamics, such as transmission rate. For example, changes to dispersal may affect the amount of inbreeding and outbreeding that occurs in this normally inbred species, and disease might be amplified in areas where aggression is increased by resource augmentation from humans. Additionally, the role that garbage plays in mongoose aggression suggests that humans may be inadvertently increasing disease incidence in this system, as well as in other taxa for which anthropogenic food augmentation may alter disease dynamics via changes in intraspecific aggression. This research sheds light on ways that behavior can influence and respond to disease that are often overlooked in disease ecology.
Buffalo and Maslow's hammer
Alexander, Kathleen A.; Blackburn, Jason K.; Frimpong, Emmanuel A. (Ecological Society of America, 2011-06)
Abraham H Maslow once said, “I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail”. Kathleen Alexander and her coauthors describe a game scout’s unsurprising finding in Botswana’s Okavango Delta, and go on to consider the statistical equivalent of that famous hammer!
Buffalo, Bush Meat, and the Zoonotic Threat of Brucellosis in Botswana
Alexander, Kathleen A.; Blackburn, Jason K.; Vandewalle, Mark Eric; Pesapane, Risa; Baipoledi, Eddie Kekgonne; Elzer, Phil H. (PLOS, 2012-03-08)
Background Brucellosis is a zoonotic disease of global importance infecting humans, domestic animals, and wildlife. Little is known about the epidemiology and persistence of brucellosis in wildlife in Southern Africa, particularly in Botswana. Methods Archived wildlife samples from Botswana (1995–2000) were screened with the Rose Bengal Test (RBT) and fluorescence polarization assay (FPA) and included the African buffalo (247), bushbuck (1), eland (5), elephant (25), gemsbok (1), giraffe (9), hartebeest (12), impala (171), kudu (27), red lechwe (10), reedbuck (1), rhino (2), springbok (5), steenbok (2), warthog (24), waterbuck (1), wildebeest (33), honey badger (1), lion (43), and zebra (21). Human case data were extracted from government annual health reports (1974–2006). Findings Only buffalo (6%, 95% CI 3.04%–8.96%) and giraffe (11%, 95% CI 0–38.43%) were confirmed seropositive on both tests. Seropositive buffalo were widely distributed across the buffalo range where cattle density was low. Human infections were reported in low numbers with most infections (46%) occurring in children (<14 years old) and no cases were reported among people working in the agricultural sector. Conclusions Low seroprevalence of brucellosis in Botswana buffalo in a previous study in 1974 and again in this survey suggests an endemic status of the disease in this species. Buffalo, a preferred source of bush meat, is utilized both legally and illegally in Botswana. Household meat processing practices can provide widespread pathogen exposure risk to family members and the community, identifying an important source of zoonotic pathogen transmission potential. Although brucellosis may be controlled in livestock populations, public health officials need to be alert to the possibility of human infections arising from the use of bush meat. This study illustrates the need for a unified approach in infectious disease research that includes consideration of both domestic and wildlife sources of infection in determining public health risks from zoonotic disease invasions.
Campylobacter in aquatic and terrestrial mammals is driven by life traits: A systematic review and meta-analysis
Brooks, Michael R.; Medley, Sarah; Ponder, Monica A.; Alexander, Kathleen A. (Frontiers, 2023-02)
Introduction: Campylobacter spp. infections are responsible for significant diarrheal disease burden across the globe, with prevalence thought to be increasing. Although wild avian species have been studied as reservoirs of Campylobacter spp., our understanding of the role of wild mammalian species in disease transmission and persistence is limited. Host factors influencing infection dynamics in wild mammals have been neglected, particularly life traits, and the role of these factors in zoonotic spillover risk is largely unknown. Methods: Here, we conducted a systematic literature review, identifying mammalian species that had been tested for Campylobacter spp. infections (molecular and culture based). We used logistic regression to evaluate the relationship between the detection of Campylobacter spp. in feces and host life traits (urban association, trophic level, and sociality). Results: Our analysis suggest that C. jejuni transmission is associated with urban living and trophic level. The probability of carriage was highest in urban-associated species (p = 0.02793) and the most informative model included trophic level. In contrast, C. coli carriage appears to be strongly influenced by sociality (p = 0.0113) with trophic level still being important. Detection of Campylobacter organisms at the genus level, however, was only associated with trophic level (p = 0.0156), highlighting the importance of this trait in exposure dynamics across host and Campylobacter pathogen systems. Discussion: While many challenges remain in the detection and characterization of Camploybacter spp., these results suggest that host life traits may have important influence on pathogen exposure and transmission dynamics, providing a useful starting point for more directed surveillance approaches.
The Challenges and Opportunities in Monitoring and Modeling Waterborne Pathogens in Water- and Resource-Restricted Africa: Highlighting the critical need for multidisciplinary research and tool advancement
Holcomb, Megan Kathleen (Virginia Tech, 2014-01-22)
Water is a primary shared resource that connects all species across the landscape and can facilitate shared exposure to a community of waterborne pathogens. Despite remarkable global progress in sanitation and hygiene development in the past two decades, infectious diarrhea remains a prominent public health threat in sub-Saharan Africa. This thesis identifies and discusses persistent challenges limiting the success of current waterborne disease management strategies and several existing research hurdles that continue to impede characterization of microbial transmission and transport. In this work, the Chobe River watershed in Northern Botswana serves as a target study site for the application of hydrological modeling tools to quantify emergent water quality and health challenges in Southern Africa. A watershed model with extensive data requirements, the Hydrological Simulation Program – Fortran (HSPF), is used to identify primary data gaps and model assumptions that limit the progress of model development, and guide opportunities for data collection, tool development, and research direction. Environmental pathogen exposure risk and epidemiological outbreak dynamics are best described by interactions between the coupled human and environmental processes within a system. The challenge of reducing diarrheal disease incidence strengthens a call for research studies and management plans that join multiple disciplines and consider a range of spatiotemporal scales.
The Changing Face of Water: A Dynamic Reflection of Antibiotic Resistance Across Landscapes
Sanderson, Claire E.; Fox, J. Tyler; Dougherty, Eric R.; Cameron, Andrew D. S.; Alexander, Kathleen A. (Frontiers, 2018-09-06)
Little is known about the role of surface water in the propagation of antibiotic resistance (AR), or the relationship between AR and water quality declines. While healthcare and agricultural sectors are considered the main contributors to AR dissemination, few studies have been conducted in their absence. Using linear models and Bayesian kriging, we evaluate AR among Escherichia coli water isolates collected bimonthly from the Chobe River in Northern Botswana (n = 1997, n = 414 water samples; July 2011–May 2012) in relation to water quality dynamics (E. coli, fecal coliform, and total suspended solids), land use, season, and AR in wildlife and humans within this system. No commercial agricultural or large medical facilities exist within this region. Here, we identify widespread AR in surface water, with land use and season significant predicators of AR levels. Mean AR was significantly higher in the wet season than the dry season (p = 0.003), and highest in the urban landscape (2.15, SD = 0.098) than the protected landscape (1.39, SD = 0.051). In-water E. coli concentrations were significantly positively associated with mean AR in the wet season (p < 0.001) but not in the dry season (p = 0.110), with TSS negatively associated with mean AR across seasons (p = 0.016 and p = 0.029), identifying temporal and spatial relationships between water quality variables and AR. Importantly, when human, water, and wildlife isolates were examined, similar AR profiles were identified (p < 0.001). Our results suggest that direct human inputs are sufficient for extensive dispersal of AR into the environment, with landscape features, season, and water quality variables influencing AR dynamics. Focused and expensive efforts to minimize pollution from agricultural sources, while important, may only provide incremental benefits to the management of AR across complex landscapes. Controlling direct human AR inputs into the environment remains a critical and pressing challenge.
Characterization of Campylobacter, Salmonella, and Diarrheagenic Escherichia Coli from Food, Food Waste and Water in the Chobe Region of Botswana
Bywater, Auja L. (Virginia Tech, 2023-06-23)
Introduction and Justification: Diarrheal disease is a leading cause of death in children in low- and moderate-income countries. Food, food waste, and water are all vehicles that can promote the spread of diarrheal disease-causing bacteria like Campylobacter, Salmonella enterica, and E. coli. Resistance to commonly used antibiotics is on the rise, making them difficult to manage. This study aimed to determine prevalence and antibiotic resistance profiles of Campylobacter, S. enterica, and E. coli isolated from food, food waste, and water samples obtained from the Chobe Region of Botswana. In addition, the survival of two common pathogens, E. coli and C. jejuni, on kale, a type of leafy green commonly consumed raw, was determined. Methods: Samples were collected from the Chobe region of Botswana in 2022 including water from the local river, food (produce, beef, pork, and poultry) from local vendors, and food scraps from the landfill. Food samples were enriched in the appropriate selective media: Brilliant Green Bile Broth for E. coli, Bolton Broth for Campylobacter, and Rappaport Vassiliadis Broth for S. enterica. Water samples were collected using modified USEPA methods1103.1 and 1604, E.coli isolation was performed by plating on RAPID E.coli2 agar and incubation at 37°C for 2h and 44°C for 16-22h. Campylobacter, S. enterica, and E. coli were isolated from meat, poultry, and water samples before being sent to Virginia Tech, while enriched bacterial pellets from the produce were shipped for screening and isolation at Virginia Tech. E.coli were confirmed by PCR detecting the phoA gene (all E. coli), and classified as pathogenic through screening for the eae (present in enterohemorrhagic and enteropathogenic E.coli), stx1 and stx2 (present in enterohemorrhagic E. coli) and est1b ( present in Enterotoxigenic E.coli) genes. Campylobacter isolates were confirmed using a genera-specific PCR while S. enterica isolates were confirmed using invA primers. These enrichment and primer sets were tested as part of a study to determine the survival of E. coli O157:H7 and C. jejuni on kale during a 21-day shelf life. E. coli and S. enterica isolates were subjected to antibiotic resistance testing using the Kirby-Bauer Disk Diffusion method. Results: Methods for detection of inoculated E. coli O157:H7 on kale indicated survival for the majority of the shelf-life (up to 19 d), in comparison, C. jejuni was undetectable by day 13 using enrichment and PCR or plating. From the Botswanan samples, E. coli was isolated from 20% of produce, 49% of meat, and 84.7% of water. Salmonella was only isolated from produce samples (2.4%, 7/294). Resistance was uncommon among the Salmonella isolates with only one isolate being resistant to chloramphenicol. No Campylobacter were isolated from the screened produce, meat, or food waste. E. coli resistant to 3 or more classes of antibiotics (MCR) were identified in 15.5% of produce, and 22.2% of meat isolates. Isolation of E. coli or Salmonella from meat was not associated with a particular food type. In contrast, isolation of E. coli was more common from certain types of vegetables and fruits. Antibiotic-resistant E. coli were isolated more commonly from beef, poultry, and pork than from produce. Multi-class resistant E. coli were isolated from fruits, greens, soil associated, and above ground associated vegetables, beef, and poultry. Water samples were collected from the same time period as the food samples. E. coli isolation, especially pathogens (based on eae presence) was more frequent from environmental water samples collected during the wet season compared to the dry season. Water samples collected during periods of increased rainfall were more likely to contain E. coli isolates, especially pathogens. S. enterica and Diarrheagenic E. coli isolates, especially MCR isolates, pose a significant risk of illness to consumers. Strategies to reduce the circulation of these pathogens in foods and water sources are needed.
Characterization of Diarrheagenic Escherichia coli Isolated from Food, Food Waste, and Water from the Chobe Region of Botswana
Bywater, Auja L.; Ponder, Monica A.; Alexander, Kathleen A. (2023-04-21)
Characterizing African Elephant (Loxodonta Africana) Population Dynamics and Distribution in Botswana
Barungwi, Amo Obusitswe (Virginia Tech, 2021-07-29)
The African elephant (Loxodonta africana) is an iconic species that is globally threatened. Of the total continental population, 37% is found in Botswana, the highest number and density of elephants in Africa. Elephant management in this country remains challenging and complex as the population estimates and trends calculated by government and independent researchers (from aerial survey data) differ and continue to be highly debated, both locally and internationally. To add more clarity and potentially resolve this ongoing debate, this study evaluates aerial survey data collected by the Botswana government from 1990 to 2012 and compares it with population demographic field data collected in 2019-2020 to assess Botswana's elephant population trend in a multimodal fashion. I used two different methods to evaluate aerial survey count data, the log-linear regression model and the Exponential Growth Space State (EGSS) model. In addition, I used the population demographic field data to estimate the growth rate. From the results, the average annual growth rate from the linear regression and the EGSS were both 6.17%. The growth rate estimated from the population demographics field data was estimated to be 5.17%. The age structure was comprised of the six age classes with a general increase from one age structure to the next as expected with a non significant decline in age class 3 (5-10 years) likely associated with the difficulty in differentiating this age class from the bounding age classes. There were no significant differences in the sex ratio (0.49Males:0.51Females). The age structure remained the same from 2019 to 2020, suggesting no evidence that overharvesting impacted the elephant population age structure in northern Botswana. Range expansion has also been identified with the movement of the elephant population into the southern part of the country by 2012. Analysis of count and demographic data as well as the identification of range expansion suggest that the elephant population is growing at rate close to the maximum growth rate previously identified for this species. Data do not support assertions that the population is negatively impacted through illegal offtake. Independent studies that identify Botswana's elephant population as declining have relied on comparisons that are made between data sets obtained from divergent aerial survey methodology and survey area, elements that confound such conclusions. Estimating population trends and the growth rate of an open population is complex, never-the-less, with population growth potientially derived from both birth and/or external immigation. However, demographic data collected in during this study indicate that the fucundity rate is substantial and likely a dominating driver of the positive population growth trend. Multiple measures of population growth (aerial survey and demographic assessments) also provide the opportunity for cross-validation of derived population trends. Therefore, this study recommends that the Botswana government incorporate population demographic data (i.e., age classes) into their existing monitoring protocols. Longitudinal data collection provides a critical mechanism for understanding population trends over changing environmental dynamics and should be continued. Efforts to modify or change these approaches must employ mechanisms that will account for and standardize for differences in methodology.
Climate Change is Likely to Worsen the Public Health Threat of Diarrheal Disease in Botswana
Alexander, Kathleen A.; Carzolio, Marcos; Goodin, Douglas; Vance, Eric A. (MDPI, 2013-03-26)
Diarrheal disease is an important health challenge, accounting for the majority of childhood deaths globally. Climate change is expected to increase the global burden of diarrheal disease but little is known regarding climate drivers, particularly in Africa. Using health data from Botswana spanning a 30-year period (1974–2003), we evaluated monthly reports of diarrheal disease among patients presenting to Botswana health facilities and compared this to climatic variables. Diarrheal case incidence presents with a bimodal cyclical pattern with peaks in March (ANOVA p < 0.001) and October (ANOVA p < 0.001) in the wet and dry season, respectively. There is a strong positive autocorrelation (p < 0.001) in the number of reported diarrhea cases at the one-month lag level. Climatic variables (rainfall, minimum temperature, and vapor pressure) predicted seasonal diarrheal with a one-month lag in variables (p < 0.001). Diarrheal case incidence was highest in the dry season after accounting for other variables, exhibiting on average a 20% increase over the yearly mean (p < 0.001). Our analysis suggests that forecasted climate change increases in temperature and decreases in precipitation may increase dry season diarrheal disease incidence with hot, dry conditions starting earlier and lasting longer. Diarrheal disease incidence in the wet season is likely to decline. Our results identify significant health-climate interactions, highlighting the need for an escalated public health focus on controlling diarrheal disease in Botswana. Study findings have application to other arid countries in Africa where diarrheal disease is a persistent public health problem.
The complexity of antibiotic resistance dynamics in scarce surface water resources in northern Botswana
Nkwalale, Lipa Gutani Terrence (Virginia Tech, 2020-09-03)
Antibiotic resistance (AR) is widely associated with intensive agricultural systems, pharmaceutical production, wastewater, and health facilities. However, little research has been conducted on AR gene (ARG) dynamics in natural environments lacking large-scale human inputs. In particular, we have a limited understanding of the complex dynamics influencing environmental AR in resource-limited dryland systems threatened by climate change. In northern Botswana, Escherichia coli isolates were obtained from river surface water (n = 426 samples; September 2017 – May 2018), sediments (n = 194; November 2017 – May 2018), and human fecal samples (n = 43 September 2017 and April 2018). A multiplex PCR assay was used to assess gene frequencies for sulfonamide (sul1 and sul2), tetracycline (tetA and tetB), and class 1 integron (intl1) resistance genes. The weighted frequency of sul1 in sediment E. coli isolates (µ= 0.07; SD = 0.39) was significantly higher than that observed in isolates obtained from surface water (µ= 0.03; SD = 0.15; p = 0.01). Weighted gene frequencies for sul1 and sul2 in human E. coli isolates from April 2018 were significantly higher than those in water (sul1 p = 0.01; sul2 p = 0.00) and sediment isolates (sul1 p = 0.01; sul2 p = 0.00) from the same time period. Significant differences for the five genes' weighted frequencies were observed between sampling months in water isolates (intl1 p = 3.318e-05; sul1 p = 3.217e-06; sul2 p = 4.392e-06; and tetA p = 2.477e-05), while only intl1 frequency differed significantly between months in sediment isolates (p = 0.05). While no significant spatial patterns of ARG frequencies were observed in E. coli isolates from water samples (p = 0.16), higher ARGs were observed in E. coli isolated from human-dominated land areas for intl1 (µ = 0.10; SD = 0.31) than in protected landscapes intl1 (µ = 0.03; SD = 0.13; p = 0.02). Land use also was associated with higher weighted frequencies for tetA in E. coli isolates from water in human-dominated land areas (µ = 0.10; SD = 0.30) compared to protected areas (µ = 0.04; SD = 0.23, p = 0.03). These results indicate that the interactions between land use and season-dependent hydrometeorological factors drive frequencies of some ARGs across this system, but do not fully explain the complexities observed. However, the lack of higher weighted gene frequencies for riverbed sediments suggests that they do not act as a reservoir for ARGs in the system, implicating humans as significant contributors to ARG persistence in the aquatic system.
Coursing hyenas and stalking lions: The potential for inter- and intraspecific interactions
Barker, Nancy A.; Joubert, Francois G.; Kasaona, Marthin; Shatumbu, Gabriel A.; Stowbunenko, Vincent; Alexander, Kathleen A.; Slotow, Rob; Getz, Wayne M. (Public Library of Science, 2023-02)
Resource partitioning promotes coexistence among guild members, and carnivores reduce interference competition through behavioral mechanisms that promote spatio-temporal separation. We analyzed sympatric lion and spotted hyena movements and activity patterns to ascertain the mechanisms facilitating their coexistence within semi-arid and wetland ecosystems. We identified recurrent high-use (revisitation) and extended stay (duration) areas within home ranges, as well as correlated movement-derived measures of inter- and intraspecific interactions with environmental variables. Spatial overlaps among lions and hyenas expanded during the wet season, and occurred at edges of home ranges, around water-points, along pathways between patches of high-use areas. Lions shared more of their home ranges with spotted hyenas in arid ecosystems, but shared more of their ranges with conspecifics in mesic environments. Despite shared space use, we found evidence for subtle temporal differences in the nocturnal movement and activity patterns between the two predators, suggesting a fine localized-scale avoidance strategy. Revisitation frequency and duration within home ranges were influenced by interspecific interactions, after land cover categories and diel cycles. Intraspecific interactions were also important for lions and, important for hyenas were moon illumination and ungulates attracted to former anthrax carcass sites in Etosha, with distance to water in Chobe/Linyanti. Recursion and duration according to locales of competitor probabilities were similar among female lions and both sexes of hyenas, but different for male lions. Our results suggest that lions and spotted hyenas mediate the potential for interference competition through subtle differences in temporal activity, fine-scale habitat use differentiation, and localized reactive-avoidance behaviors. These findings enhance our understanding of the potential effects of interspecific interactions among large carnivore space-use patterns within an apex predator system and show adaptability across heterogeneous and homogeneous environments. Future conservation plans should emphasize the importance of inter- and intraspecific competition within large carnivore communities, particularly moderating such effects within increasingly fragmented landscapes.
Creeping in the night: What might ecologists be missing?
Nichols, Carol Anne; Alexander, Kathleen A. (PLOS, 2018-06-13)
Wildlife activity patterns tend to be defined by terms such as diurnal and nocturnal that might not fully depict the complexity of a species' life history strategy and behavior in a given system. These activity pattern categories often influence the methodological approaches employed, including the temporal period of study (daylight or nighttime). We evaluated banded mongoose (Mungos mungo) behavior in Northern Botswana through the use of remote sensing cameras at active den sites in order to characterize early morning behavior for this diurnal species. Our approach, however, provided the facility to capture unexpected nocturnal activity in a species that had otherwise only been studied during daylight hours. Camera traps were deployed for 215 trap days (24 hour data capture period) at den sites, capturing 5,472 photos over all events. Nocturnal activity was identified in 3% of trap days at study den sites with both vigilant and non-vigilant nocturnal behaviors identified. While vigilant behaviors involved troop fleeing responses, observations of non-vigilant behaviors suggest nonresident mongoose may investigate den sites of other troops during nocturnal time periods. There was no association between the occurrence of nocturnal activity and lunar phase (Fisher's exact test, n = 215, p = 0.638) and thus, increased moonlight was not identified as a factor influencing nocturnal behavior. The drivers and fitness consequences of these nocturnal activities remain uncertain and present intriguing areas for future research. Our findings highlight the need for ecological studies to more explicitly address and evaluate the potential for temporal variability in activity periods. Modifying our approach and embracing variation in wildlife activity patterns might provide new insights into the interaction between ecological phenomenon and species biology that spans the diurnal-nocturnal spectrum.
Diet and Feeding Ecology of the Coyotes, Black Bears, and Bobcats in Western Virginia and Preliminary Assessment of Coyote Parasites
Montague, David Miles (Virginia Tech, 2014-10-22)
Although deer abundance is high throughout most areas of Virginia, parts of western Virginia, especially on public lands, have comparatively low density deer populations. Concerns voiced by sportsmen regarding declining deer numbers in this region prompted interest in research to investigate the role of predation on deer populations. The coyote (Canis latrans) is a relative newcomer to Virginia, and relatively little is known about the role coyotes play in Virginia ecosystem dynamics, including their interactions with other sympatric predators. Research studies in other areas suggest that predation from coyotes, bobcats (Lynx rufus), and black bears (Ursus americanus) may be a significant source of deer (Odocoileus virginianus) mortality, especially for fawns, and the cumulative effects of predation from these sources may also increase the potential for additive mortality in deer populations. An important consideration when comparing feeding strategies of carnivores is the relative availability of food items across the landscape. I estimated the relative seasonal availability of several potential food items in a mosaic landscape that included some areas of prescribed burning and variable timber harvest in the mountains of western Virginia between June 2011 and May 2013. I focused on 4 broad categories of food items: white-tailed deer, mid-sized mammals (raccoons, Procyon lotor, opossums, Didelphis virginiana, cottontails, Sylvilagus spp., and squirrels, Sciurus spp.), small mammals, and soft mast. I used distance sampling to estimate deer density, camera trapping techniques to estimate mid-sized mammal trapping rates and occupancy, mark-recapture techniques to estimate small mammal abundance, and vegetation sampling to estimate % cover, which I used as measures of food availability for predation. To estimate carnivore diet, I analyzed scats of coyotes (n = 334), bobcats (n = 258), and black bears (n = 107) collected monthly from June 2011 and May 2013. Additionally, I compared estimates of % occurrence to estimates of seasonal availability of deer, mid-sized mammals, small mammals, and soft mast by ranking availability of food items from 0 (unavailable) to 4 (highly available) from my monthly and seasonal food item abundance and density estimates. I then ranked % occurrence in scat on a 0 - 4 scale and compared diet rankings to food item availability where changes in rank indicate differences from the generalist diet. Deer densities were substantially higher in Bath County (4.75 - 16.06 deer/km²) than in Rockingham County (0.17 - 3.55 deer/km²). I estimated availability of other food items only in Bath County. For mid-sized mammals, I estimated low activity as shown by constant, but low, trapping rates (#photo events/trap nights*100) of opossums, and relatively higher, constant trapping rates of cottontails. Raccoon and squirrel trapping rates were highly variable across seasons and raccoon occupancy (proportion of sites occupied) was higher in summer and fall (0.51 - 0.59) whereas squirrel occupancy was highest in October-November (0.51 - 0.53). Cottontail and opossum occupancies were higher in burned areas (0.40 - 0.57, 0.24 - 0.46, respectively), whereas raccoon and gray squirrel occupancies were higher in unburned areas (0.23 - 0.78, 0.12 - 0.58, respectively). Using program MARK I estimated high abundance and density of Peromyscus spp. in all seasons relative to other small mammal species. Densities of meadow voles and jumping mice were high seasonally in open field habitat. Densities of eastern chipmunks, red-backed voles, and Peromyscus spp. were significantly higher in burned areas relative to unburned sites. Among soft mast species, blueberries comprised the largest % occurrence. I expect a generalist predator to consume deer at a constant rate and have lower % deer occurrence in Rockingham County where deer densities are much lower. I expect seasonally constant, but low, occurrence of opossum and relatively higher, but similarly constant, occurrence of cottontail. I expect raccoon occurrence to be relatively high in summer and fall, and lower in winter. Squirrel occurrence should peak in October and November, followed by a steady decline until June. Based on availability, Peromyscus spp. should be the most commonly occurring small mammal in the diet of a generalist predator, rivaled by meadow voles (Clethrionomys gapperi) in fall and perhaps summer. I expect chipmunks (Tamias striatus) and red-backed voles to occur at constant but low rates in predator diets. I predict that various species of soft mast may occur during their respective fruiting seasons. Deer were the most frequently occurring food item of coyotes in all months in both counties, with % biomass consumed highest in June (Bath: 60.0 - 90.9 %; Rockingham: 55.6 - 92.3%). Deer occurrence in bobcat scat peaked in June (77.54 %). In black bear scat, deer occurrence was highest in February and March (100 %), however sample sizes in these months were extremely low (n = 2, 3 respectively). All 3 predators consumed deer more than expected in June and July. In most months, coyotes consumed deer and soft mast more often than expected (1 rank higher) and they consumed deer much higher (2-3 ranks higher) than expected in January and February. While deer was a major food item in the diets of all 3 predators, it is unclear whether this observed result was caused by predation or scavenging. It is unlikely that coyotes, bears, or bobcats are preying on adult deer with high frequency. I did not estimate the availability of deer carcasses for scavenging in this study. If deer carcasses are highly available in the study area, this may explain the high occurrence of deer in carnivore scat and the lack of seasonality in coyote samples. Mice (Peromyscus spp.) were consumed by predators less than expected based on availability, whereas squirrels and chipmunks were consumed by bobcats more than expected. Meadow and red-backed voles were consumed more than expected by both bobcats and coyotes. Mid-sized mammals occurred with expected frequency or lower in predator scats. Coyotes had the lowest diversity and variation in diet, whereas bobcat and bear diets were more diverse including seasonal use of many species. Coyotes exhibited more selectivity (based on changes, and magnitude of changes, in rankings for food item occurrence versus availability) and appear more specialized on deer in all months than bobcats. I analyzed 203 randomly-selected coyote fecal samples using a modified Wisconsin fecal flotation technique. I identified 13 parasite taxa, 9 of which occurred with adequate frequency to permit statistical analysis. No landscape patterns or statistically significant seasonal differences were found in prevalence of parasite taxa, and only A. caninum and Eimeria spp. were significantly higher, and Cystoisospora spp. was somewhat significantly higher, in Bath versus Rockingham Counties. By comparing my data on spatio-temporal patterns of food availability to patterns in the scats of predators, we have better understanding of predator foraging strategies and can identify opportunities for targeted management to balance predator-prey dynamics with human needs and values. More research is needed on the interactions of sympatric predators in specific areas to gain further inferences regarding population-level impacts of predation on deer in western Virginia.
Do not feed the wildlife: associations between garbage use, aggression, and disease in banded mongooses (Mungos Mungo)
Flint, Bonnie Fairbanks; Hawley, Dana M.; Alexander, Kathleen A. (Wiley, 2016-07-25)
Urbanization and other human modifications of the landscape may indirectly affect disease dynamics by altering host behavior in ways that influence pathogen transmission. Few opportunities arise to investigate behaviorally mediated effects of human habitat modification in natural host–pathogen systems, but we provide a potential example of this phenomenon in banded mongooses (Mungos mungo), a social mammal. Our banded mongoose study population in Botswana is endemically infected with a novel Mycobacterium tuberculosis complex pathogen, M. mungi, that primarily invades the mongoose host through the nasal planum and breaks in the skin. In this system, several study troops have access to human garbage sites and other modified landscapes for foraging. Banded mongooses in our study site (N = 4 troops, ~130 individuals) had significantly higher within-troop aggression levels when foraging in garbage compared to other foraging habitats. Second, monthly rates of aggression were a significant predictor of monthly number of injuries in troops. Finally, injured individuals had a 75% incidence of clinical tuberculosis (TB) compared to a 0% incidence in visibly uninjured mongooses during the study period. Our data suggest that mongoose troops that forage in garbage may be at greater risk of acquiring TB by incurring injuries that may allow for pathogen invasion. Our study suggests the need to consider the indirect effects of garbage on behavior and wildlife health when developing waste management approaches in human-modified areas.

Browsing by Author "Alexander, Kathleen A."

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