Christina Ahlstrom, Ph.D.
Christina is a Research Biologist for the Alaska Science Center.
My research aims to better understand wildlife and zoonotic diseases in Alaska and adjacent regions. I use molecular tools to investigate the genetic diversity and transmission pathways of pathogens in wildlife populations and the ecosystems they occupy. My main research topics include antimicrobial resistance in wild birds, avian influenza, and Giardia and Cryptosporidium parasites in Arctic Alaska. I strive to achieve a more comprehensive understanding of where pathogens are detected and their genetic relatedness among spatio-temporally diverse populations to help inform management actions aimed to interrupt transmission pathways.
Professional Experience
2024 - Present Research Biologist, USGS Alaska Science Center, Anchorage, Alaska
2017 - 2023 Geneticist, USGS Alaska Science Center, Anchorage, Alaska
2015 - 2017 Consultant Epidemiologist & Data Analyst, Epi-interactive, Wellington, New Zealand
2017 Molecular Epidemiology Consultant, Food and Agriculture Organisation, Rome, Italy
2016 Molecular Epidemiology Consultant, Food and Agriculture Organisation, Rome, Italy
2005 - 2008 Seasonal Research Assistant, Quality Milk Production Services, Cornell University, Ithaca, NY
Education and Certifications
Ph.D. 2015 University of Calgary, Calgary, Alberta, Canada Veterinary Medical Sciences
M.S. 2011 Colorado State University, Fort Collins, CO Animal Science
B.S. 2008 University at Buffalo, Buffalo, NY Biology
Science and Products
Filter Total Items: 15
Sampling, Antimicrobial Resistance Testing, and Genomic Typing of E. coli in Gulls (Larus spp.) on the Kenai Peninsula, Alaska, 2016 Sampling, Antimicrobial Resistance Testing, and Genomic Typing of E. coli in Gulls (Larus spp.) on the Kenai Peninsula, Alaska, 2016
This data set includes information on collections of fecal or cloacal samples from wild gulls (Larus spp.) at four locations on the Kenai Peninsula, Alaska, USA. Samples were also collected from sockeye salmon harvested as part of the personal-use fisheries on the Kenai and Kasilof Rivers. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple...
Influenza A Virus Data from Migratory Birds, Izembek National Wildlife Refuge, Alaska Influenza A Virus Data from Migratory Birds, Izembek National Wildlife Refuge, Alaska
Dataset containing avian influenza screening results for waterfowl and gulls sampled during autumn in (or near) Izembek National Wildlife Refuge (NWR), Alaska, 2011-2024. These data contain information on species, age, and sex of birds sampled, collection dates, and laboratory testing information used to determine the presence and absence of influenza A viruses (IAVs).
Sampling and Resistance and Genomic Typing of Cephalosporin-resistant E. coli in Gulls (Larus spp.) and Bald Eagles (Haliaeetus leucocephalus) in Southcentral Alaska, 2016 Sampling and Resistance and Genomic Typing of Cephalosporin-resistant E. coli in Gulls (Larus spp.) and Bald Eagles (Haliaeetus leucocephalus) in Southcentral Alaska, 2016
This data set includes information on collections of fecal or cloacal samples from wild birds at a location in Alaska, USA. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple antibiotics. These data were used to identify and genetically compare antibiotic-resistant E. coli isolates in wild migratory birds inhabiting a landfill habitat in Alaska...
Filter Total Items: 20
Comparative genomics and genomic epidemiology of mycobacterium avium subsp. paratuberculosis strains Comparative genomics and genomic epidemiology of mycobacterium avium subsp. paratuberculosis strains
Two phenotypically distinct strains of Mycobacterium avium subsp. paratuberculosis (MAP) were recognized in the 1930s but it was not until the introduction of restriction endonuclease analysis (REA) in the mid-1980s that these two strains, MAP-C and MAP-S, could be distinguished genetically. Since then, a plethora of molecular typing techniques has been applied to MAP isolates (reviewed...
Authors
Karen Stevenson, Christina Ahlstrom
Validation of a screening method for the detection of colistin-resistant E. coli containing mcr-1 in feral swine feces Validation of a screening method for the detection of colistin-resistant E. coli containing mcr-1 in feral swine feces
A method was developed and validated for the detection of colistin-resistant Escherichia coli containing mcr-1 in the feces of feral swine. Following optimization of an enrichment method using EC broth supplemented with colistin (1 µg/mL) and vancomycin (8 µg/mL), aliquots derived from 100 feral swine fecal samples were spiked with of one of five different mcr-1 positive E. coli strains...
Authors
Jeffrey C Chandler, Alan B. Franklin, Sarah N. Bevins, Kevin T Bentler, Jonas Bonnedahl, Christina Ahlstrom, Bledar Bisha, Susan A. Shriner
Gulls as sources of environmental contamination by colistin-resistant bacteria Gulls as sources of environmental contamination by colistin-resistant bacteria
In 2015, the mcr-1 gene was discovered in Escherichia coli in domestic swine in China that conferred resistance to colistin, an antibiotic of last resort used in treating multi-drug resistant bacterial infections in humans. Since then, mcr-1 was found in other human and animal populations, including wild gulls. Because gulls could disseminate the mcr-1 gene, we conducted an experiment to...
Authors
Alan B. Franklin, Andrew M. Ramey, Kevin T Bentler, Nicole L Barret, Loredana M McCurdy, Christina Ahlstrom, Jonas Bonnedahl, Susan A. Shriner, Jeffrey C Chandler
Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions
The proliferation of antibiotic resistant bacteria in the environment has potential negative economic and health consequences. Thus, previous investigations have targeted wild animals to understand the occurrence of antibiotic resistance in diverse environmental sources. In this critical review and synthesis, we summarize important concepts learned through the sampling of wildlife for...
Authors
Andrew M. Ramey, Christina Ahlstrom
Early emergence of mcr-1-positive Enterobacteriaceae in gulls from Spain and Portugal Early emergence of mcr-1-positive Enterobacteriaceae in gulls from Spain and Portugal
We tested extended‐spectrum β‐lactamase producing bacteria from wild gulls (Larusspp.) sampled in 2009 for the presence of mcr‐1. We report the detection of mcr‐1 and describe genome characteristics of four Escherichia coli and one Klebsiella pneumoniaeisolate from Spain and Portugal that also exhibited colistin resistance. Results represent the earliest evidence for colistin‐resistant...
Authors
Christina Ahlstrom, Andrew M. Ramey, Hanna Woksepp, Jonas Bonnedahl
Repeated detection of carbapenemase-producing Escherichia coli in gulls inhabiting Alaska, USA Repeated detection of carbapenemase-producing Escherichia coli in gulls inhabiting Alaska, USA
We report the first detection of carbapenemase-producing Escherichia coli in Alaska and in wildlife in the United States. Wild bird (gull) feces sampled at three locations in Southcentral Alaska yielded isolates that harbored plasmid-encoded blaKPC-2 or chromosomally-encoded blaOXA-48, and genes associated with antimicrobial resistance to up to eight antibiotic classes.
Authors
Christina Ahlstrom, Andrew M. Ramey, Hanna Woksepp, Jonas Bonnedahl
Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska
Gulls (Larus spp.) have frequently been reported to carry Escherichia coli exhibiting antimicrobial resistance (AMR E. coli); however, the pathways governing the acquisition and dispersal of such bacteria are not well-described. We equipped 17 landfill-foraging gulls with satellite transmitters and collected gull fecal samples longitudinally from four locations on the Kenai Peninsula...
Authors
Christina Ahlstrom, Jonas Bonnedahl, Hanna Woksepp, Jorge Hernandez, John Reed, T. Lee Tibbitts, Bjorn Olsen, David C. Douglas, Andrew M. Ramey
Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis
Antimicrobial resistance (AMR) in bacterial pathogens threatens global health, though the spread of AMR bacteria and AMR genes between humans, animals, and the environment is still largely unknown. Here, we investigated the role of wild birds in the epidemiology of AMR Escherichia coli. Using next-generation sequencing, we characterized cephalosporin-resistant E. coli cultured from...
Authors
Christina Ann Ahlstrom, Jonas Bonnedahl, Hanna Woksepp, Jorge Hernandez, Olsen Bjorn, Andrew M. Ramey
Non-USGS Publications**
Muellner, U., G. Fournie, P. Muellner, C. A. Ahlstrom, and D. U. Pfeiffer. 2018. Epidemix - an Interactive Multi-Model Application for Teaching and Visualizing Infectious Disease Transmission. Epidemics 23:49-54. doi:10.1016/j.epidem.2017.12.003.
Ahlstrom, C. A., P. Muellner, G. Lammers, M. Jones, S. Octavia, R. Lan, and J. Heller. 2017. Shiga-toxin producing E. coli O157 shedding dynamics in an Australian beef herd. Frontiers in Veterinary Science 4:200. doi:10.3389/fvets.2017.00200.
Ahlstrom, C. A., C. S. Manuel, H. C. Den Bakker, M. Wiedmann, and K. K. Nightingale. 2017. Molecular Ecology of Listeria spp., Salmonella, Escherichia coli O157:H7, and non-O157 Shiga Toxin Producing Escherichia coli in Pristine Natural Environments in Northern Colorado. Journal of Applied Microbiology. doi:10.1111/jam.13657.
Ahlstrom, C. A., P. Muellner, S. Spencer, S. Hong, A. Saupe, A. Rovira, C. Hedberg, A. Perez, and J. Alvarez. 2017. Inferring source attribution from a multi-year multi-source dataset of Salmonella in Minnesota. Zoonoses and Public Health 64(8):589-598. doi:10.1111/zph.12351.
Bauman, C. A., A. Jones-Bitton, C. A. Ahlstrom, L. Mutharia, J. De Buck, J. Jansen, D. F. Kelton, and P. Menzies. 2017. Identification of Mycobacterium avium ssp. paratuberculosis strains isolated from dairy goats and dairy sheep in Ontario, Canada. Canadian Journal of Veterinary Research 81(4):304-307.
Hong, S., A. Rovira, P. Davies, C. A. Ahlstrom, P. Muellner, A. Rendahl, K. Olsen, J. B. Bender, S. Wells, A. Perez, and J. Alvarez. 2016. Serotypes and antimicrobial resistance in Salmonella enterica recovered from clinical samples from cattle and swine in Minnesota, 2006 to 2015. International Journal of Parasitology: Parasites and Wildlife 11(12):e0168016. doi:10.1371/journal.pone.0168016.
Muellner, P., U. Muellner, M. C. Gates, T. Pearce, C. A. Ahlstrom, D. O'Neill, D. Brodbelt, and N. J. Cave. 2016. Evidence in Practice – A Pilot Study Leveraging Companion Animal and Equine Health Data from Primary Care Veterinary Clinics in New Zealand. Frontiers in Veterinary Science 3:116. doi:10.3389/fvets.2016.00116.
Davidson, F., C. A. Ahlstrom, J. De Buck, H. G. Whitney, and K. Tahlan. 2016. Examination of Mycobacterium avium subspecies paratuberculosis mixed genotype infections in dairy animals using a whole genome sequencing approach. PeerJ 4:e2793. doi:10.7717/peerj.2793.
Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2016. Relative frequency of 4 major strain types of Mycobacterium avium ssp. paratuberculosis in Canadian dairy herds using a novel single nucleotide polymorphism-based polymerase chain reaction. Journal of Dairy Science 99(10):8297-8303. doi:10.3168/jds.2016-11397.
Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, K. Tahlan, and J. De Buck. 2016. Genome-wide diversity and phylogeography of Mycobacterium avium subsp. paratuberculosis in Canadian dairy cattle. PLoS One 11:e0149017. doi:10.1371/journal.pone.0149017.
Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, S. Hendrick, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, and J. De Buck. 2015. Limitations of variable number of tandem repeat typing identified through whole genome sequencing of Mycobacterium avium subsp. paratuberculosis on a national and herd level. BMC Genomics 16:161. doi:10.1186/s12864-015-1387-6.
Den Bakker, H. C., S. Warchocki, E. M. Wright, A. F. Allred, C. A. Ahlstrom, C. S. Manuel, M. J. Stasiewicz, A. Burrell, S. Roof, L. Strawn, E. D. Fortes, K. K. Nightingale, D. Kephart, and M. Wiedmann. 2014. Listeria floridensis sp. nov., Listeria aquatica sp. nov., Listeria cornellensis sp. nov., Listeria riparia sp. nov., and Listeria grandensis sp. nov., from agricultural and natural environments. International Journal of Systematic and Evolutionary Microbiology 64:1882-1889. doi:10.1099/ijs.0.052720-0.
Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2014. Improved Short-Sequence-Repeat Genotyping of Mycobacterium avium subsp. paratuberculosis by Using Matrix-Assisted Laser Desorption Ionization—Time of Flight Mass Spectrometry. Applied and Environmental Microbiology 80:534-539. doi:10.1128/AEM.03212-13.
Zadoks, R. N., H. M. Griffiths, M. A. Munoz, C. A. Ahlstrom, G. J. Bennett, E. Thomas, and Y. H. Schukken. 2011. Sources of Klebsiella and Raoultella species on dairy farms: be careful where you walk. Journal of Dairy Science 94(2):1045-1051. doi:10.3168/jds.2010-3603.
Munoz, M. A., G. J. Bennett, C. A. Ahlstrom, H. M. Griffiths, Y. H. Schukken, and R. N. Zadoks. 2008. Cleanliness Scores as Indicator of Klebsiella Exposure in Dairy Cows. Journal of Dairy Science 91(10):3908-3916. doi:10.3168/jds.2008-1090.
Munoz, M. A., C. A. Ahlstrom, B. J. Rauch, and R. N. Zadoks. 2006. Fecal Shedding of Klebsiella pneumoniae by Dairy Cows. Journal of Dairy Science 89(9):3425-3430. doi:10.3168/jds.S0022-0302(06)72379-7.
Muellner, P., D. Hodges, C. A. Ahlstrom, M. Newman, R. Davidson, D. U. Pfeiffer, J. Marshall, and C. Morley. 2018. Creating a framework for the prioritization of biosecurity risks to the New Zealand dairy industry. Transboundary and Emerging Diseases 65(4):1067-1077. doi:10.1111/tbed.12848.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 15
Sampling, Antimicrobial Resistance Testing, and Genomic Typing of E. coli in Gulls (Larus spp.) on the Kenai Peninsula, Alaska, 2016 Sampling, Antimicrobial Resistance Testing, and Genomic Typing of E. coli in Gulls (Larus spp.) on the Kenai Peninsula, Alaska, 2016
This data set includes information on collections of fecal or cloacal samples from wild gulls (Larus spp.) at four locations on the Kenai Peninsula, Alaska, USA. Samples were also collected from sockeye salmon harvested as part of the personal-use fisheries on the Kenai and Kasilof Rivers. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple...
Influenza A Virus Data from Migratory Birds, Izembek National Wildlife Refuge, Alaska Influenza A Virus Data from Migratory Birds, Izembek National Wildlife Refuge, Alaska
Dataset containing avian influenza screening results for waterfowl and gulls sampled during autumn in (or near) Izembek National Wildlife Refuge (NWR), Alaska, 2011-2024. These data contain information on species, age, and sex of birds sampled, collection dates, and laboratory testing information used to determine the presence and absence of influenza A viruses (IAVs).
Sampling and Resistance and Genomic Typing of Cephalosporin-resistant E. coli in Gulls (Larus spp.) and Bald Eagles (Haliaeetus leucocephalus) in Southcentral Alaska, 2016 Sampling and Resistance and Genomic Typing of Cephalosporin-resistant E. coli in Gulls (Larus spp.) and Bald Eagles (Haliaeetus leucocephalus) in Southcentral Alaska, 2016
This data set includes information on collections of fecal or cloacal samples from wild birds at a location in Alaska, USA. Samples were screened for Escherichia coli (E. coli) and tested for resistance to multiple antibiotics. These data were used to identify and genetically compare antibiotic-resistant E. coli isolates in wild migratory birds inhabiting a landfill habitat in Alaska...
Filter Total Items: 20
Comparative genomics and genomic epidemiology of mycobacterium avium subsp. paratuberculosis strains Comparative genomics and genomic epidemiology of mycobacterium avium subsp. paratuberculosis strains
Two phenotypically distinct strains of Mycobacterium avium subsp. paratuberculosis (MAP) were recognized in the 1930s but it was not until the introduction of restriction endonuclease analysis (REA) in the mid-1980s that these two strains, MAP-C and MAP-S, could be distinguished genetically. Since then, a plethora of molecular typing techniques has been applied to MAP isolates (reviewed...
Authors
Karen Stevenson, Christina Ahlstrom
Validation of a screening method for the detection of colistin-resistant E. coli containing mcr-1 in feral swine feces Validation of a screening method for the detection of colistin-resistant E. coli containing mcr-1 in feral swine feces
A method was developed and validated for the detection of colistin-resistant Escherichia coli containing mcr-1 in the feces of feral swine. Following optimization of an enrichment method using EC broth supplemented with colistin (1 µg/mL) and vancomycin (8 µg/mL), aliquots derived from 100 feral swine fecal samples were spiked with of one of five different mcr-1 positive E. coli strains...
Authors
Jeffrey C Chandler, Alan B. Franklin, Sarah N. Bevins, Kevin T Bentler, Jonas Bonnedahl, Christina Ahlstrom, Bledar Bisha, Susan A. Shriner
Gulls as sources of environmental contamination by colistin-resistant bacteria Gulls as sources of environmental contamination by colistin-resistant bacteria
In 2015, the mcr-1 gene was discovered in Escherichia coli in domestic swine in China that conferred resistance to colistin, an antibiotic of last resort used in treating multi-drug resistant bacterial infections in humans. Since then, mcr-1 was found in other human and animal populations, including wild gulls. Because gulls could disseminate the mcr-1 gene, we conducted an experiment to...
Authors
Alan B. Franklin, Andrew M. Ramey, Kevin T Bentler, Nicole L Barret, Loredana M McCurdy, Christina Ahlstrom, Jonas Bonnedahl, Susan A. Shriner, Jeffrey C Chandler
Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions
The proliferation of antibiotic resistant bacteria in the environment has potential negative economic and health consequences. Thus, previous investigations have targeted wild animals to understand the occurrence of antibiotic resistance in diverse environmental sources. In this critical review and synthesis, we summarize important concepts learned through the sampling of wildlife for...
Authors
Andrew M. Ramey, Christina Ahlstrom
Early emergence of mcr-1-positive Enterobacteriaceae in gulls from Spain and Portugal Early emergence of mcr-1-positive Enterobacteriaceae in gulls from Spain and Portugal
We tested extended‐spectrum β‐lactamase producing bacteria from wild gulls (Larusspp.) sampled in 2009 for the presence of mcr‐1. We report the detection of mcr‐1 and describe genome characteristics of four Escherichia coli and one Klebsiella pneumoniaeisolate from Spain and Portugal that also exhibited colistin resistance. Results represent the earliest evidence for colistin‐resistant...
Authors
Christina Ahlstrom, Andrew M. Ramey, Hanna Woksepp, Jonas Bonnedahl
Repeated detection of carbapenemase-producing Escherichia coli in gulls inhabiting Alaska, USA Repeated detection of carbapenemase-producing Escherichia coli in gulls inhabiting Alaska, USA
We report the first detection of carbapenemase-producing Escherichia coli in Alaska and in wildlife in the United States. Wild bird (gull) feces sampled at three locations in Southcentral Alaska yielded isolates that harbored plasmid-encoded blaKPC-2 or chromosomally-encoded blaOXA-48, and genes associated with antimicrobial resistance to up to eight antibiotic classes.
Authors
Christina Ahlstrom, Andrew M. Ramey, Hanna Woksepp, Jonas Bonnedahl
Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska
Gulls (Larus spp.) have frequently been reported to carry Escherichia coli exhibiting antimicrobial resistance (AMR E. coli); however, the pathways governing the acquisition and dispersal of such bacteria are not well-described. We equipped 17 landfill-foraging gulls with satellite transmitters and collected gull fecal samples longitudinally from four locations on the Kenai Peninsula...
Authors
Christina Ahlstrom, Jonas Bonnedahl, Hanna Woksepp, Jorge Hernandez, John Reed, T. Lee Tibbitts, Bjorn Olsen, David C. Douglas, Andrew M. Ramey
Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis Acquisition and dissemination of cephalosporin-resistant E. coli in migratory birds sampled at an Alaska landfill as inferred through genomic analysis
Antimicrobial resistance (AMR) in bacterial pathogens threatens global health, though the spread of AMR bacteria and AMR genes between humans, animals, and the environment is still largely unknown. Here, we investigated the role of wild birds in the epidemiology of AMR Escherichia coli. Using next-generation sequencing, we characterized cephalosporin-resistant E. coli cultured from...
Authors
Christina Ann Ahlstrom, Jonas Bonnedahl, Hanna Woksepp, Jorge Hernandez, Olsen Bjorn, Andrew M. Ramey
Non-USGS Publications**
Muellner, U., G. Fournie, P. Muellner, C. A. Ahlstrom, and D. U. Pfeiffer. 2018. Epidemix - an Interactive Multi-Model Application for Teaching and Visualizing Infectious Disease Transmission. Epidemics 23:49-54. doi:10.1016/j.epidem.2017.12.003.
Ahlstrom, C. A., P. Muellner, G. Lammers, M. Jones, S. Octavia, R. Lan, and J. Heller. 2017. Shiga-toxin producing E. coli O157 shedding dynamics in an Australian beef herd. Frontiers in Veterinary Science 4:200. doi:10.3389/fvets.2017.00200.
Ahlstrom, C. A., C. S. Manuel, H. C. Den Bakker, M. Wiedmann, and K. K. Nightingale. 2017. Molecular Ecology of Listeria spp., Salmonella, Escherichia coli O157:H7, and non-O157 Shiga Toxin Producing Escherichia coli in Pristine Natural Environments in Northern Colorado. Journal of Applied Microbiology. doi:10.1111/jam.13657.
Ahlstrom, C. A., P. Muellner, S. Spencer, S. Hong, A. Saupe, A. Rovira, C. Hedberg, A. Perez, and J. Alvarez. 2017. Inferring source attribution from a multi-year multi-source dataset of Salmonella in Minnesota. Zoonoses and Public Health 64(8):589-598. doi:10.1111/zph.12351.
Bauman, C. A., A. Jones-Bitton, C. A. Ahlstrom, L. Mutharia, J. De Buck, J. Jansen, D. F. Kelton, and P. Menzies. 2017. Identification of Mycobacterium avium ssp. paratuberculosis strains isolated from dairy goats and dairy sheep in Ontario, Canada. Canadian Journal of Veterinary Research 81(4):304-307.
Hong, S., A. Rovira, P. Davies, C. A. Ahlstrom, P. Muellner, A. Rendahl, K. Olsen, J. B. Bender, S. Wells, A. Perez, and J. Alvarez. 2016. Serotypes and antimicrobial resistance in Salmonella enterica recovered from clinical samples from cattle and swine in Minnesota, 2006 to 2015. International Journal of Parasitology: Parasites and Wildlife 11(12):e0168016. doi:10.1371/journal.pone.0168016.
Muellner, P., U. Muellner, M. C. Gates, T. Pearce, C. A. Ahlstrom, D. O'Neill, D. Brodbelt, and N. J. Cave. 2016. Evidence in Practice – A Pilot Study Leveraging Companion Animal and Equine Health Data from Primary Care Veterinary Clinics in New Zealand. Frontiers in Veterinary Science 3:116. doi:10.3389/fvets.2016.00116.
Davidson, F., C. A. Ahlstrom, J. De Buck, H. G. Whitney, and K. Tahlan. 2016. Examination of Mycobacterium avium subspecies paratuberculosis mixed genotype infections in dairy animals using a whole genome sequencing approach. PeerJ 4:e2793. doi:10.7717/peerj.2793.
Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2016. Relative frequency of 4 major strain types of Mycobacterium avium ssp. paratuberculosis in Canadian dairy herds using a novel single nucleotide polymorphism-based polymerase chain reaction. Journal of Dairy Science 99(10):8297-8303. doi:10.3168/jds.2016-11397.
Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, K. Tahlan, and J. De Buck. 2016. Genome-wide diversity and phylogeography of Mycobacterium avium subsp. paratuberculosis in Canadian dairy cattle. PLoS One 11:e0149017. doi:10.1371/journal.pone.0149017.
Ahlstrom, C. A., H. W. Barkema, K. Stevenson, R. N. Zadoks, R. Biek, R. Kao, H. Trewby, S. Hendrick, D. Haupstein, D. F. Kelton, G. Fecteau, O. Labrecque, G. P. Keefe, S. L. B. McKenna, and J. De Buck. 2015. Limitations of variable number of tandem repeat typing identified through whole genome sequencing of Mycobacterium avium subsp. paratuberculosis on a national and herd level. BMC Genomics 16:161. doi:10.1186/s12864-015-1387-6.
Den Bakker, H. C., S. Warchocki, E. M. Wright, A. F. Allred, C. A. Ahlstrom, C. S. Manuel, M. J. Stasiewicz, A. Burrell, S. Roof, L. Strawn, E. D. Fortes, K. K. Nightingale, D. Kephart, and M. Wiedmann. 2014. Listeria floridensis sp. nov., Listeria aquatica sp. nov., Listeria cornellensis sp. nov., Listeria riparia sp. nov., and Listeria grandensis sp. nov., from agricultural and natural environments. International Journal of Systematic and Evolutionary Microbiology 64:1882-1889. doi:10.1099/ijs.0.052720-0.
Ahlstrom, C. A., H. W. Barkema, and J. De Buck. 2014. Improved Short-Sequence-Repeat Genotyping of Mycobacterium avium subsp. paratuberculosis by Using Matrix-Assisted Laser Desorption Ionization—Time of Flight Mass Spectrometry. Applied and Environmental Microbiology 80:534-539. doi:10.1128/AEM.03212-13.
Zadoks, R. N., H. M. Griffiths, M. A. Munoz, C. A. Ahlstrom, G. J. Bennett, E. Thomas, and Y. H. Schukken. 2011. Sources of Klebsiella and Raoultella species on dairy farms: be careful where you walk. Journal of Dairy Science 94(2):1045-1051. doi:10.3168/jds.2010-3603.
Munoz, M. A., G. J. Bennett, C. A. Ahlstrom, H. M. Griffiths, Y. H. Schukken, and R. N. Zadoks. 2008. Cleanliness Scores as Indicator of Klebsiella Exposure in Dairy Cows. Journal of Dairy Science 91(10):3908-3916. doi:10.3168/jds.2008-1090.
Munoz, M. A., C. A. Ahlstrom, B. J. Rauch, and R. N. Zadoks. 2006. Fecal Shedding of Klebsiella pneumoniae by Dairy Cows. Journal of Dairy Science 89(9):3425-3430. doi:10.3168/jds.S0022-0302(06)72379-7.
Muellner, P., D. Hodges, C. A. Ahlstrom, M. Newman, R. Davidson, D. U. Pfeiffer, J. Marshall, and C. Morley. 2018. Creating a framework for the prioritization of biosecurity risks to the New Zealand dairy industry. Transboundary and Emerging Diseases 65(4):1067-1077. doi:10.1111/tbed.12848.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.