This project focuses on brucellosis, a bacterial infection of elk, bison and cattle in the Greater Yellowstone Ecosystem. Since 2004, several instances of brucellosis transmission from wildlife to livestock have resulted in cattle outbreaks in Wyoming, Idaho, and Montana. This research will provide critical scientific information to the multiple State and Federal agencies responsible for wildlife and livestock in this region. The specific research objectives are to: (1) determine whether brucellosis prevalence of elk can be reduced on the supplemental feedgrounds of Wyoming using two ecological field manipulations; (2) determine the effects of changing land-ownership, irrigation, predation, and hunting on elk group size distributions and brucellosis prevalence; and (3) estimate the amount of intraspecific brucellosis transmission among elk populations and the interspecific transmission among elk, bison, and cattle using a combination of host and pathogen DNA markers and genomics.
The researchers will assess how contact and disease transmission are related to host aggregation, and how host aggregations, in turn, are affected by land-use, habitat, hunting, and predators. The relationship between host density and parasite transmission is fundamental to understanding the dynamics of infectious disease transmission. Models predict that when transmission is correlated with host density, there is a host density threshold below which the parasite will be unable to persist as the density is reduced. This forms the basis for using social distancing (such as school closures) to reduce the spread of pandemics. In natural systems, the density-transmission relationship is the justification for strategies such as culling, sterilization, and vaccination, which aim to reduce the density of susceptible individuals.
The problem of managing Brucella in the Greater Yellowstone Ecosystem is of direct and immediate importance for wildlife management and conservation in this flagship American ecosystem. The researchers will provide information to natural resource managers through biennual meetings and will disseminate free novel software for genetic analyses of pathogen dynamics. The project also will: provide research and training opportunities for undergraduate and graduate students, with a particular goal of recruiting Native American students; foster the participation of scientists in programs with GK-12 teachers and students; and support public outreach through films and podcasts developed by students in the Science and Natural History Filmmaking program at Montana State and through the educational outreach program at Yellowstone National Park.
PI: Gordon Luikart Awardee: University of Montana Award Number: 1067613 Brucellosis is among the most common and problematic bacterial-caused diseases for livestock, wildlife, and humans worldwide. Brucellosis is reemerging in the northern Rocky Mountains around Yellowstone Park and increasing costs of livestock production and wildlife management. Elk are thought to be the primary source of brucellosis outbreaks in domestic livestock and wildlife. Unfortunately, little is known about elk herd genetic connectivity. Population genetic connectivity occurs when elk herds (breeding groups) exchange animals (i.e., dispersal) with successful reproduction, which leads to gene flow among herds but is also associated with brucellosis (and other disease) spread across the Greater Yellowstone Area (GYA). A main goal of our project was to quantify genetic connectivity (gene flow) and long-distance movement patterns among elk herds across the GYA in order to better understand the potential for, and pathways of, brucellosis spatial spread. We assessed and mapped both female and male long-distance movement patterns by comparing female-transmitted DNA (mitochondrial DNA) and DNA that is transmitted by both parents (nuclear DNA markers). We also developed novel, sensitive DNA-based diagnostic tests for early detection of brucellosis bacteria (Brucella) in tissue, blood, feces, and urine. This DNA-based diagnostic test improves our understanding of Brucella transmission by detecting both live and dead bacteria, increasing our ability to use environmental samples (e.g., snow). To achieve project goals, we developed improved "landscape genetic mapping" methods and new genomic analysis (genome-wide genotyping) laboratory methods. We provided freely available computer software to facilitate both the landscape genetic mapping approaches and the genotyping approaches (http://flbs.umt.edu/people/Hand~3461/default.aspx?ID=3461). This is one of the first studies to combine several new approaches in genomic analysis for wildlife species and a pathogen to better understand how the landscape, disease infection and transmission, and wildlife movement patterns interact. These tools and our improved understanding of long-term elk movement and disease transmission patterns are helping to guide management and monitoring efforts to mitigate and eliminate brucellosis. Our data collection efforts will provide some of the largest and first "landscape genomic" studies in wildlife. With collaborators, we have helped collect over 500 elk blood and tissue samples and 400 bison samples with associated data on disease status (brucellosis infection), and geographic population of origin of the elk, bison, and matched Brucella DNA isolates (Brucella bacteria strains). We have compiled databases listing genetic characteristics of elk and bison that will be useful for not only addressing our current question, but as baseline data for monitoring the genetic and disease status of herds in the future. Our research helped identify corridors of long-distance elk movement (dispersal), which are useful for inferring long-distance disease transmission pathways. We also identified landscape features and locations where elk dispersal is relatively limited and where management actions might help monitor and reduce elk (and disease) movement. Our research will help identify genes (and genome regions) associated with disease resistance in elk and bison, which can help monitor effects of disease on wildlife population abundance, and also to help maximize disease resistance in wildlife populations (e.g., when initiating new herds including genes for disease resistance). DNA-based diagnostic tests (such as the ones we also developed here) can help livestock and wildlife managers with culling (removal) of those animals most likely to be shedding and transmitting brucellosis, which is not generally feasible with existing approaches (e.g., serology and culture). Our rapid DNA-based PCR (polymerase chain reaction) tests will be extremely valuable to managers because they were shown to reliably detect Brucella in blood, urine, and lymph node tissue when only a few cells of the bacteria were present. Our project trained 3 graduate students who have subsequently found jobs in research and education (e.g., at a tribal college) in genomics and wildlife conservation. Our project also trained several undergraduate students and six technicians in field and laboratory research. The project facilitated communication, coordination, and collaboration between state agencies (including Montana Fish Wildlife and Parks, Idaho Fish and Game, and Wyoming Game and Fish), federal agencies (including US Geological Survey, Yellowstone and Grand Teton National Parks, APHIS [Animal and Plant Health Inspection Service], NADC [National Animal Disease Center], and NVSL [National Veterinary Services Laboratories]), and universities (Montana State, University of Montana, and University of Wyoming). Finally, our collaborative project developed a website and multiple videos to help educate the public, managers, and researchers about brucellosis, wildlife disease, and genetics (http://vimeo.com/33527913; www.gyebrucellosis.net).
